* [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
@ 2023-04-04 3:33 kernel test robot
0 siblings, 0 replies; 7+ messages in thread
From: kernel test robot @ 2023-04-04 3:33 UTC (permalink / raw)
To: oe-kbuild; +Cc: lkp, Dan Carpenter
BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-kernel@vger.kernel.org
TO: "Paul E. McKenney" <paulmck@kernel.org>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
head: e222f9a512539c3f4093a55d16624d9da614800b
commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
:::::: branch date: 6 hours ago
:::::: commit date: 3 days ago
config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 12.1.0
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
smatch warnings:
kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
vim +/jlimit +2149 kernel/rcu/tree.c
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2060
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2061 /*
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2062 * Invoke any RCU callbacks that have made it to the end of their grace
a616aec9aa140e kernel/rcu/tree.c Ingo Molnar 2021-03-22 2063 * period. Throttle as specified by rdp->blimit.
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2064 */
5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
cfcdef5e30469f kernel/rcu/tree.c Eric Dumazet 2019-07-24 2150 break;
a554ba288845fd kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2151 } else {
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2152 // In rcuc/rcuoc context, so no worries about
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2153 // depriving other softirq vectors of CPU cycles.
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2154 local_bh_enable();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2155 lockdep_assert_irqs_enabled();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2156 cond_resched_tasks_rcu_qs();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2157 lockdep_assert_irqs_enabled();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2158 local_bh_disable();
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2159 // But rcuc kthreads can delay quiescent-state
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2160 // reporting, so check time limits for them.
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2161 if (rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING &&
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2162 rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit)) {
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2163 rdp->rcu_cpu_has_work = 1;
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2164 break;
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2165 }
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2166 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2167 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2168
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2169 rcu_nocb_lock_irqsave(rdp, flags);
e816d56fad57ba kernel/rcu/tree.c Paul E. McKenney 2020-05-01 2170 rdp->n_cbs_invoked += count;
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2171 trace_rcu_batch_end(rcu_state.name, count, !!rcl.head, need_resched(),
5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2172 is_idle_task(current), rcu_is_callbacks_kthread(rdp));
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2173
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2174 /* Update counts and requeue any remaining callbacks. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2175 rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);
6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2176) rcu_segcblist_add_len(&rdp->cblist, -count);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2177
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2178 /* Reinstate batch limit if we have worked down the excess. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2179 count = rcu_segcblist_n_cbs(&rdp->cblist);
d5a9a8c3bc8068 kernel/rcu/tree.c Paul E. McKenney 2019-04-10 2180 if (rdp->blimit >= DEFAULT_MAX_RCU_BLIMIT && count <= qlowmark)
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2181 rdp->blimit = blimit;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2182
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2183 /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2184 if (count == 0 && rdp->qlen_last_fqs_check != 0) {
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2185 rdp->qlen_last_fqs_check = 0;
2431774f04d105 kernel/rcu/tree.c Paul E. McKenney 2021-07-20 2186 rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2187 } else if (count < rdp->qlen_last_fqs_check - qhimark)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2188 rdp->qlen_last_fqs_check = count;
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2189
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2190 /*
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2191 * The following usually indicates a double call_rcu(). To track
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2192 * this down, try building with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2193 */
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2194) empty = rcu_segcblist_empty(&rdp->cblist);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2195) WARN_ON_ONCE(count == 0 && !empty);
d1b222c6be1f8b kernel/rcu/tree.c Paul E. McKenney 2019-07-02 2196 WARN_ON_ONCE(!IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2197) count != 0 && empty);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2198) WARN_ON_ONCE(count == 0 && rcu_segcblist_n_segment_cbs(&rdp->cblist) != 0);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2199) WARN_ON_ONCE(!empty && rcu_segcblist_n_segment_cbs(&rdp->cblist) == 0);
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2200
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2201 rcu_nocb_unlock_irqrestore(rdp, flags);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2202
6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2203 tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2204 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2205
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
2023-04-04 14:43 ` Dan Carpenter
@ 2023-04-04 14:56 ` Paul E. McKenney
0 siblings, 0 replies; 7+ messages in thread
From: Paul E. McKenney @ 2023-04-04 14:56 UTC (permalink / raw)
To: Dan Carpenter; +Cc: oe-kbuild, lkp, oe-kbuild-all, linux-kernel
On Tue, Apr 04, 2023 at 05:43:54PM +0300, Dan Carpenter wrote:
> On Tue, Apr 04, 2023 at 06:47:18AM -0700, Paul E. McKenney wrote:
> > On Tue, Apr 04, 2023 at 07:43:22AM +0300, Dan Carpenter wrote:
> > > On Mon, Apr 03, 2023 at 09:18:58PM -0700, Paul E. McKenney wrote:
> > > > On Tue, Apr 04, 2023 at 07:04:06AM +0300, Dan Carpenter wrote:
> > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
> > > > > head: e222f9a512539c3f4093a55d16624d9da614800b
> > > > > commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
> > > > > config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
> > > > > compiler: or1k-linux-gcc (GCC) 12.1.0
> > > > >
> > > > > If you fix the issue, kindly add following tag where applicable
> > > > > | Reported-by: kernel test robot <lkp@intel.com>
> > > > > | Reported-by: Dan Carpenter <error27@gmail.com>
> > > > > | Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
> > > > >
> > > > > smatch warnings:
> > > > > kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
> > > > >
> > > > > vim +/jlimit +2149 kernel/rcu/tree.c
> > > > >
> > > > > 5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
> > > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
> > > > > b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
> > > > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
> > > > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
> > > > > 4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
> > > > > 5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
> > > > > 29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
> > > > > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
> > > > > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
> > > > > 8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
> > > > > 253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
> > > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
> > > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
> > > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
> > > > > 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
> > > > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > > > jlimit is only initialized if one of these conditions is met.
> > > > >
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
> > > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
> > > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
> > > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
> > > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
> > > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
> > > > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
> > > > > 344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
> > > > > 7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
> > > > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
> > > > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
> > > > > 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
> > > > > 6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
> > > > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
> > > > > 6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
> > > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
> > > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
> > > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
> > > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
> > > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
> > > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
> > > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
> > > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
> > > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
> > > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
> > > > > ^^^^^^
> > > > > Uninitialized?
> > > >
> > > > Except that in rcu_do_batch_check_time(), jlimit is referenced only if
> > > > jlimit_check is set, which it is only if jlimit is initialized.
> > > >
> > > > I suppose that I could unconditionally initialize jlimit to (say) zero
> > > > to shut this up, but is there a better way to communicate the intent
> > > > to the tooling?
> > > >
> > > > Or am I confused and there is a real use of the uninitialized value?
> > > >
> > > > Thanx, Paul
> > >
> > > I'm going to guess that on distro kernels they're going to automatically
> > > initialize stack variables to zero. So it's not a bad option.
> > >
> > > The other thing is that rcu_do_batch_check_time() is always going to be
> > > inlined. So this is officially a false positive. If it weren't inlined
> > > then passing uninitialized data is a bug regardless of whether or not
> > > it's used.
> > >
> > > It's also totally okay to just ignore this false positive.
> >
> > Would another approach be would to pass the address of jlimit in to
> > rcu_do_batch_check_time()? Taking the address of local variables usually
> > suppresses some optimizations, though perhaps not important ones.
>
> That would work for Smatch but it seems like an ugly approach. Better
> to just ignore it.
Very well, you got it! ;-)
Thanx, Paul
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
2023-04-04 13:47 ` Paul E. McKenney
@ 2023-04-04 14:43 ` Dan Carpenter
2023-04-04 14:56 ` Paul E. McKenney
0 siblings, 1 reply; 7+ messages in thread
From: Dan Carpenter @ 2023-04-04 14:43 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: oe-kbuild, lkp, oe-kbuild-all, linux-kernel
On Tue, Apr 04, 2023 at 06:47:18AM -0700, Paul E. McKenney wrote:
> On Tue, Apr 04, 2023 at 07:43:22AM +0300, Dan Carpenter wrote:
> > On Mon, Apr 03, 2023 at 09:18:58PM -0700, Paul E. McKenney wrote:
> > > On Tue, Apr 04, 2023 at 07:04:06AM +0300, Dan Carpenter wrote:
> > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
> > > > head: e222f9a512539c3f4093a55d16624d9da614800b
> > > > commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
> > > > config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
> > > > compiler: or1k-linux-gcc (GCC) 12.1.0
> > > >
> > > > If you fix the issue, kindly add following tag where applicable
> > > > | Reported-by: kernel test robot <lkp@intel.com>
> > > > | Reported-by: Dan Carpenter <error27@gmail.com>
> > > > | Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
> > > >
> > > > smatch warnings:
> > > > kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
> > > >
> > > > vim +/jlimit +2149 kernel/rcu/tree.c
> > > >
> > > > 5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
> > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
> > > > b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
> > > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
> > > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
> > > > 4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
> > > > 5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
> > > > 29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
> > > > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
> > > > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
> > > > 8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
> > > > 253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
> > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
> > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
> > > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
> > > > 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
> > > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > > jlimit is only initialized if one of these conditions is met.
> > > >
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
> > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
> > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
> > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
> > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
> > > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
> > > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
> > > > 344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
> > > > 7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
> > > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
> > > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
> > > > 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
> > > > 6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
> > > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
> > > > 6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
> > > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
> > > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
> > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
> > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
> > > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
> > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
> > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
> > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
> > > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
> > > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
> > > > ^^^^^^
> > > > Uninitialized?
> > >
> > > Except that in rcu_do_batch_check_time(), jlimit is referenced only if
> > > jlimit_check is set, which it is only if jlimit is initialized.
> > >
> > > I suppose that I could unconditionally initialize jlimit to (say) zero
> > > to shut this up, but is there a better way to communicate the intent
> > > to the tooling?
> > >
> > > Or am I confused and there is a real use of the uninitialized value?
> > >
> > > Thanx, Paul
> >
> > I'm going to guess that on distro kernels they're going to automatically
> > initialize stack variables to zero. So it's not a bad option.
> >
> > The other thing is that rcu_do_batch_check_time() is always going to be
> > inlined. So this is officially a false positive. If it weren't inlined
> > then passing uninitialized data is a bug regardless of whether or not
> > it's used.
> >
> > It's also totally okay to just ignore this false positive.
>
> Would another approach be would to pass the address of jlimit in to
> rcu_do_batch_check_time()? Taking the address of local variables usually
> suppresses some optimizations, though perhaps not important ones.
That would work for Smatch but it seems like an ugly approach. Better
to just ignore it.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
2023-04-04 4:43 ` Dan Carpenter
@ 2023-04-04 13:47 ` Paul E. McKenney
2023-04-04 14:43 ` Dan Carpenter
0 siblings, 1 reply; 7+ messages in thread
From: Paul E. McKenney @ 2023-04-04 13:47 UTC (permalink / raw)
To: Dan Carpenter; +Cc: oe-kbuild, lkp, oe-kbuild-all, linux-kernel
On Tue, Apr 04, 2023 at 07:43:22AM +0300, Dan Carpenter wrote:
> On Mon, Apr 03, 2023 at 09:18:58PM -0700, Paul E. McKenney wrote:
> > On Tue, Apr 04, 2023 at 07:04:06AM +0300, Dan Carpenter wrote:
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
> > > head: e222f9a512539c3f4093a55d16624d9da614800b
> > > commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
> > > config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
> > > compiler: or1k-linux-gcc (GCC) 12.1.0
> > >
> > > If you fix the issue, kindly add following tag where applicable
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Reported-by: Dan Carpenter <error27@gmail.com>
> > > | Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
> > >
> > > smatch warnings:
> > > kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
> > >
> > > vim +/jlimit +2149 kernel/rcu/tree.c
> > >
> > > 5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
> > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
> > > b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
> > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
> > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
> > > 4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
> > > 5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
> > > 29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
> > > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
> > > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
> > > 8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
> > > 253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
> > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
> > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
> > > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
> > > 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > jlimit is only initialized if one of these conditions is met.
> > >
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
> > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
> > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
> > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
> > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
> > > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
> > > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
> > > 344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
> > > 7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
> > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
> > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
> > > 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
> > > 6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
> > > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
> > > 6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
> > > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
> > > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
> > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
> > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
> > > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
> > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
> > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
> > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
> > > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
> > > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
> > > ^^^^^^
> > > Uninitialized?
> >
> > Except that in rcu_do_batch_check_time(), jlimit is referenced only if
> > jlimit_check is set, which it is only if jlimit is initialized.
> >
> > I suppose that I could unconditionally initialize jlimit to (say) zero
> > to shut this up, but is there a better way to communicate the intent
> > to the tooling?
> >
> > Or am I confused and there is a real use of the uninitialized value?
> >
> > Thanx, Paul
>
> I'm going to guess that on distro kernels they're going to automatically
> initialize stack variables to zero. So it's not a bad option.
>
> The other thing is that rcu_do_batch_check_time() is always going to be
> inlined. So this is officially a false positive. If it weren't inlined
> then passing uninitialized data is a bug regardless of whether or not
> it's used.
>
> It's also totally okay to just ignore this false positive.
Would another approach be would to pass the address of jlimit in to
rcu_do_batch_check_time()? Taking the address of local variables usually
suppresses some optimizations, though perhaps not important ones.
Thanx, Paul
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
2023-04-04 4:18 ` Paul E. McKenney
@ 2023-04-04 4:43 ` Dan Carpenter
2023-04-04 13:47 ` Paul E. McKenney
0 siblings, 1 reply; 7+ messages in thread
From: Dan Carpenter @ 2023-04-04 4:43 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: oe-kbuild, lkp, oe-kbuild-all, linux-kernel
On Mon, Apr 03, 2023 at 09:18:58PM -0700, Paul E. McKenney wrote:
> On Tue, Apr 04, 2023 at 07:04:06AM +0300, Dan Carpenter wrote:
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
> > head: e222f9a512539c3f4093a55d16624d9da614800b
> > commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
> > config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
> > compiler: or1k-linux-gcc (GCC) 12.1.0
> >
> > If you fix the issue, kindly add following tag where applicable
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Reported-by: Dan Carpenter <error27@gmail.com>
> > | Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
> >
> > smatch warnings:
> > kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
> >
> > vim +/jlimit +2149 kernel/rcu/tree.c
> >
> > 5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
> > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
> > b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
> > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
> > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
> > 4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
> > 5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
> > 29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
> > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
> > 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
> > 8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
> > 253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
> > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
> > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
> > b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
> > 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > jlimit is only initialized if one of these conditions is met.
> >
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
> > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
> > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
> > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
> > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
> > a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
> > 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
> > 344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
> > 7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
> > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
> > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
> > 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
> > 6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
> > 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
> > 6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
> > 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
> > 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
> > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
> > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
> > 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
> > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
> > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
> > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
> > 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
> > a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
> > ^^^^^^
> > Uninitialized?
>
> Except that in rcu_do_batch_check_time(), jlimit is referenced only if
> jlimit_check is set, which it is only if jlimit is initialized.
>
> I suppose that I could unconditionally initialize jlimit to (say) zero
> to shut this up, but is there a better way to communicate the intent
> to the tooling?
>
> Or am I confused and there is a real use of the uninitialized value?
>
> Thanx, Paul
I'm going to guess that on distro kernels they're going to automatically
initialize stack variables to zero. So it's not a bad option.
The other thing is that rcu_do_batch_check_time() is always going to be
inlined. So this is officially a false positive. If it weren't inlined
then passing uninitialized data is a bug regardless of whether or not
it's used.
It's also totally okay to just ignore this false positive.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
2023-04-04 4:04 Dan Carpenter
@ 2023-04-04 4:18 ` Paul E. McKenney
2023-04-04 4:43 ` Dan Carpenter
0 siblings, 1 reply; 7+ messages in thread
From: Paul E. McKenney @ 2023-04-04 4:18 UTC (permalink / raw)
To: Dan Carpenter; +Cc: oe-kbuild, lkp, oe-kbuild-all, linux-kernel
On Tue, Apr 04, 2023 at 07:04:06AM +0300, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
> head: e222f9a512539c3f4093a55d16624d9da614800b
> commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
> config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
> compiler: or1k-linux-gcc (GCC) 12.1.0
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <error27@gmail.com>
> | Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
>
> smatch warnings:
> kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
>
> vim +/jlimit +2149 kernel/rcu/tree.c
>
> 5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
> b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
> b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
> 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
> 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
> 4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
> 5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
> 29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
> 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
> 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
> 8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
> 253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
> b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
> b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
> b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> jlimit is only initialized if one of these conditions is met.
>
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
> a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
> a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
> a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
> a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
> a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
> 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
> 344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
> 7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
> 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
> 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
> 6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
> 3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
> 6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
> 77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
> 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
> 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
> 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
> 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
> 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
> 3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
> ^^^^^^
> Uninitialized?
Except that in rcu_do_batch_check_time(), jlimit is referenced only if
jlimit_check is set, which it is only if jlimit is initialized.
I suppose that I could unconditionally initialize jlimit to (say) zero
to shut this up, but is there a better way to communicate the intent
to the tooling?
Or am I confused and there is a real use of the uninitialized value?
Thanx, Paul
> cfcdef5e30469f kernel/rcu/tree.c Eric Dumazet 2019-07-24 2150 break;
> a554ba288845fd kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2151 } else {
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2152 // In rcuc/rcuoc context, so no worries about
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2153 // depriving other softirq vectors of CPU cycles.
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2154 local_bh_enable();
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2155 lockdep_assert_irqs_enabled();
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2156 cond_resched_tasks_rcu_qs();
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2157 lockdep_assert_irqs_enabled();
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2158 local_bh_disable();
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2159 // But rcuc kthreads can delay quiescent-state
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2160 // reporting, so check time limits for them.
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2161 if (rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING &&
> a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2162 rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit)) {
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2163 rdp->rcu_cpu_has_work = 1;
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2164 break;
> 70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2165 }
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2166 }
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2167 }
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2168
> 7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2169 rcu_nocb_lock_irqsave(rdp, flags);
> e816d56fad57ba kernel/rcu/tree.c Paul E. McKenney 2020-05-01 2170 rdp->n_cbs_invoked += count;
> 3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2171 trace_rcu_batch_end(rcu_state.name, count, !!rcl.head, need_resched(),
> 5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2172 is_idle_task(current), rcu_is_callbacks_kthread(rdp));
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2173
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2174 /* Update counts and requeue any remaining callbacks. */
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2175 rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);
> 6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2176) rcu_segcblist_add_len(&rdp->cblist, -count);
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2177
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2178 /* Reinstate batch limit if we have worked down the excess. */
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2179 count = rcu_segcblist_n_cbs(&rdp->cblist);
> d5a9a8c3bc8068 kernel/rcu/tree.c Paul E. McKenney 2019-04-10 2180 if (rdp->blimit >= DEFAULT_MAX_RCU_BLIMIT && count <= qlowmark)
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2181 rdp->blimit = blimit;
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2182
> 37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2183 /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2184 if (count == 0 && rdp->qlen_last_fqs_check != 0) {
> 37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2185 rdp->qlen_last_fqs_check = 0;
> 2431774f04d105 kernel/rcu/tree.c Paul E. McKenney 2021-07-20 2186 rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2187 } else if (count < rdp->qlen_last_fqs_check - qhimark)
> 15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2188 rdp->qlen_last_fqs_check = count;
> efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2189
> efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2190 /*
> efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2191 * The following usually indicates a double call_rcu(). To track
> efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2192 * this down, try building with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.
> efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2193 */
> b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2194) empty = rcu_segcblist_empty(&rdp->cblist);
> b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2195) WARN_ON_ONCE(count == 0 && !empty);
> d1b222c6be1f8b kernel/rcu/tree.c Paul E. McKenney 2019-07-02 2196 WARN_ON_ONCE(!IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2197) count != 0 && empty);
> b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2198) WARN_ON_ONCE(count == 0 && rcu_segcblist_n_segment_cbs(&rdp->cblist) != 0);
> b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2199) WARN_ON_ONCE(!empty && rcu_segcblist_n_segment_cbs(&rdp->cblist) == 0);
> 37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2200
> 5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2201 rcu_nocb_unlock_irqrestore(rdp, flags);
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2202
> 6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2203 tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
> 64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2204 }
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
@ 2023-04-04 4:04 Dan Carpenter
2023-04-04 4:18 ` Paul E. McKenney
0 siblings, 1 reply; 7+ messages in thread
From: Dan Carpenter @ 2023-04-04 4:04 UTC (permalink / raw)
To: oe-kbuild, Paul E. McKenney; +Cc: lkp, oe-kbuild-all, linux-kernel
tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
head: e222f9a512539c3f4093a55d16624d9da614800b
commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 12.1.0
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Link: https://lore.kernel.org/r/202304041113.A5sNFc2y-lkp@intel.com/
smatch warnings:
kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
vim +/jlimit +2149 kernel/rcu/tree.c
5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
jlimit is only initialized if one of these conditions is met.
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
^^^^^^
Uninitialized?
cfcdef5e30469f kernel/rcu/tree.c Eric Dumazet 2019-07-24 2150 break;
a554ba288845fd kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2151 } else {
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2152 // In rcuc/rcuoc context, so no worries about
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2153 // depriving other softirq vectors of CPU cycles.
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2154 local_bh_enable();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2155 lockdep_assert_irqs_enabled();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2156 cond_resched_tasks_rcu_qs();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2157 lockdep_assert_irqs_enabled();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2158 local_bh_disable();
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2159 // But rcuc kthreads can delay quiescent-state
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2160 // reporting, so check time limits for them.
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2161 if (rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING &&
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2162 rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit)) {
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2163 rdp->rcu_cpu_has_work = 1;
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2164 break;
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2165 }
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2166 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2167 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2168
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2169 rcu_nocb_lock_irqsave(rdp, flags);
e816d56fad57ba kernel/rcu/tree.c Paul E. McKenney 2020-05-01 2170 rdp->n_cbs_invoked += count;
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2171 trace_rcu_batch_end(rcu_state.name, count, !!rcl.head, need_resched(),
5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2172 is_idle_task(current), rcu_is_callbacks_kthread(rdp));
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2173
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2174 /* Update counts and requeue any remaining callbacks. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2175 rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);
6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2176) rcu_segcblist_add_len(&rdp->cblist, -count);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2177
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2178 /* Reinstate batch limit if we have worked down the excess. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2179 count = rcu_segcblist_n_cbs(&rdp->cblist);
d5a9a8c3bc8068 kernel/rcu/tree.c Paul E. McKenney 2019-04-10 2180 if (rdp->blimit >= DEFAULT_MAX_RCU_BLIMIT && count <= qlowmark)
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2181 rdp->blimit = blimit;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2182
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2183 /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2184 if (count == 0 && rdp->qlen_last_fqs_check != 0) {
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2185 rdp->qlen_last_fqs_check = 0;
2431774f04d105 kernel/rcu/tree.c Paul E. McKenney 2021-07-20 2186 rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2187 } else if (count < rdp->qlen_last_fqs_check - qhimark)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2188 rdp->qlen_last_fqs_check = count;
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2189
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2190 /*
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2191 * The following usually indicates a double call_rcu(). To track
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2192 * this down, try building with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2193 */
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2194) empty = rcu_segcblist_empty(&rdp->cblist);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2195) WARN_ON_ONCE(count == 0 && !empty);
d1b222c6be1f8b kernel/rcu/tree.c Paul E. McKenney 2019-07-02 2196 WARN_ON_ONCE(!IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2197) count != 0 && empty);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2198) WARN_ON_ONCE(count == 0 && rcu_segcblist_n_segment_cbs(&rdp->cblist) != 0);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2199) WARN_ON_ONCE(!empty && rcu_segcblist_n_segment_cbs(&rdp->cblist) == 0);
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2200
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2201 rcu_nocb_unlock_irqrestore(rdp, flags);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2202
6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2203 tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2204 }
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-04-04 14:56 UTC | newest]
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-- links below jump to the message on this page --
2023-04-04 3:33 [paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit' kernel test robot
2023-04-04 4:04 Dan Carpenter
2023-04-04 4:18 ` Paul E. McKenney
2023-04-04 4:43 ` Dan Carpenter
2023-04-04 13:47 ` Paul E. McKenney
2023-04-04 14:43 ` Dan Carpenter
2023-04-04 14:56 ` Paul E. McKenney
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