From: Peter Zijlstra <peterz@infradead.org>
To: gor@linux.ibm.com, jpoimboe@redhat.com, jikos@kernel.org,
mbenes@suse.cz, pmladek@suse.com, mingo@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
joe.lawrence@redhat.com, fweisbec@gmail.com, tglx@linutronix.de,
hca@linux.ibm.com, svens@linux.ibm.com, sumanthk@linux.ibm.com,
live-patching@vger.kernel.org, paulmck@kernel.org,
rostedt@goodmis.org, x86@kernel.org
Subject: [PATCH v2 02/11] sched,rcu: Rework try_invoke_on_locked_down_task()
Date: Wed, 29 Sep 2021 17:17:25 +0200 [thread overview]
Message-ID: <20210929152428.649944917@infradead.org> (raw)
In-Reply-To: 20210929151723.162004989@infradead.org
Give try_invoke_on_locked_down_task() a saner name and have it return
an int so that the caller might distinguish between different reasons
of failure.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
---
include/linux/wait.h | 3 ++-
kernel/rcu/tasks.h | 12 ++++++------
kernel/rcu/tree_stall.h | 8 ++++----
kernel/sched/core.c | 6 +++---
4 files changed, 15 insertions(+), 14 deletions(-)
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -1160,6 +1160,7 @@ int autoremove_wake_function(struct wait
(wait)->flags = 0; \
} while (0)
-bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg);
+typedef int (*task_call_f)(struct task_struct *p, void *arg);
+extern int task_call_func(struct task_struct *p, task_call_f func, void *arg);
#endif /* _LINUX_WAIT_H */
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -928,7 +928,7 @@ static void trc_read_check_handler(void
}
/* Callback function for scheduler to check locked-down task. */
-static bool trc_inspect_reader(struct task_struct *t, void *arg)
+static int trc_inspect_reader(struct task_struct *t, void *arg)
{
int cpu = task_cpu(t);
bool in_qs = false;
@@ -939,7 +939,7 @@ static bool trc_inspect_reader(struct ta
// If no chance of heavyweight readers, do it the hard way.
if (!ofl && !IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
- return false;
+ return -EINVAL;
// If heavyweight readers are enabled on the remote task,
// we can inspect its state despite its currently running.
@@ -947,7 +947,7 @@ static bool trc_inspect_reader(struct ta
n_heavy_reader_attempts++;
if (!ofl && // Check for "running" idle tasks on offline CPUs.
!rcu_dynticks_zero_in_eqs(cpu, &t->trc_reader_nesting))
- return false; // No quiescent state, do it the hard way.
+ return -EINVAL; // No quiescent state, do it the hard way.
n_heavy_reader_updates++;
if (ofl)
n_heavy_reader_ofl_updates++;
@@ -962,7 +962,7 @@ static bool trc_inspect_reader(struct ta
t->trc_reader_checked = true;
if (in_qs)
- return true; // Already in quiescent state, done!!!
+ return 0; // Already in quiescent state, done!!!
// The task is in a read-side critical section, so set up its
// state so that it will awaken the grace-period kthread upon exit
@@ -970,7 +970,7 @@ static bool trc_inspect_reader(struct ta
atomic_inc(&trc_n_readers_need_end); // One more to wait on.
WARN_ON_ONCE(READ_ONCE(t->trc_reader_special.b.need_qs));
WRITE_ONCE(t->trc_reader_special.b.need_qs, true);
- return true;
+ return 0;
}
/* Attempt to extract the state for the specified task. */
@@ -992,7 +992,7 @@ static void trc_wait_for_one_reader(stru
// Attempt to nail down the task for inspection.
get_task_struct(t);
- if (try_invoke_on_locked_down_task(t, trc_inspect_reader, NULL)) {
+ if (!task_call_func(t, trc_inspect_reader, NULL)) {
put_task_struct(t);
return;
}
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -240,16 +240,16 @@ struct rcu_stall_chk_rdr {
* Report out the state of a not-running task that is stalling the
* current RCU grace period.
*/
-static bool check_slow_task(struct task_struct *t, void *arg)
+static int check_slow_task(struct task_struct *t, void *arg)
{
struct rcu_stall_chk_rdr *rscrp = arg;
if (task_curr(t))
- return false; // It is running, so decline to inspect it.
+ return -EBUSY; // It is running, so decline to inspect it.
rscrp->nesting = t->rcu_read_lock_nesting;
rscrp->rs = t->rcu_read_unlock_special;
rscrp->on_blkd_list = !list_empty(&t->rcu_node_entry);
- return true;
+ return 0;
}
/*
@@ -283,7 +283,7 @@ static int rcu_print_task_stall(struct r
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
while (i) {
t = ts[--i];
- if (!try_invoke_on_locked_down_task(t, check_slow_task, &rscr))
+ if (task_call_func(t, check_slow_task, &rscr))
pr_cont(" P%d", t->pid);
else
pr_cont(" P%d/%d:%c%c%c%c",
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4106,7 +4106,7 @@ try_to_wake_up(struct task_struct *p, un
}
/**
- * try_invoke_on_locked_down_task - Invoke a function on task in fixed state
+ * task_call_func - Invoke a function on task in fixed state
* @p: Process for which the function is to be invoked, can be @current.
* @func: Function to invoke.
* @arg: Argument to function.
@@ -4119,12 +4119,12 @@ try_to_wake_up(struct task_struct *p, un
* Returns:
* Whatever @func returns
*/
-bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
+int task_call_func(struct task_struct *p, task_call_f func, void *arg)
{
struct rq *rq = NULL;
unsigned int state;
struct rq_flags rf;
- bool ret = false;
+ int ret;
raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
next prev parent reply other threads:[~2021-09-29 16:08 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 15:17 [PATCH v2 00/11] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 01/11] sched: Improve try_invoke_on_locked_down_task() Peter Zijlstra
2021-09-29 15:17 ` Peter Zijlstra [this message]
2021-09-29 15:17 ` [PATCH v2 03/11] sched,livepatch: Use task_call_func() Peter Zijlstra
2021-10-05 11:40 ` Petr Mladek
2021-10-05 14:03 ` Peter Zijlstra
2021-10-06 8:59 ` Miroslav Benes
2021-09-29 15:17 ` [PATCH v2 04/11] sched: Simplify wake_up_*idle*() Peter Zijlstra
2021-10-13 14:32 ` Qian Cai
2021-10-19 3:47 ` Qian Cai
2021-10-19 8:56 ` Peter Zijlstra
2021-10-19 9:10 ` Peter Zijlstra
2021-10-19 15:32 ` Qian Cai
2021-10-19 15:50 ` Peter Zijlstra
2021-10-19 19:22 ` Qian Cai
2021-10-19 20:27 ` Peter Zijlstra
[not found] ` <CGME20211022134630eucas1p2e79e2816587d182c580459d567c1f2a9@eucas1p2.samsung.com>
2021-10-22 13:46 ` Marek Szyprowski
2021-09-29 15:17 ` [PATCH v2 05/11] sched,livepatch: Use wake_up_if_idle() Peter Zijlstra
2021-10-05 12:00 ` Petr Mladek
2021-10-06 9:16 ` Miroslav Benes
2021-10-07 9:18 ` Vasily Gorbik
2021-10-07 10:02 ` Peter Zijlstra
2021-10-13 19:37 ` Arnd Bergmann
2021-10-14 10:42 ` Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 06/11] context_tracking: Prefix user_{enter,exit}*() Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 07/11] context_tracking: Add an atomic sequence/state count Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 08/11] context_tracking,rcu: Replace RCU dynticks counter with context_tracking Peter Zijlstra
2021-09-29 18:37 ` Paul E. McKenney
2021-09-29 19:09 ` Peter Zijlstra
2021-09-29 19:11 ` Peter Zijlstra
2021-09-29 19:13 ` Peter Zijlstra
2021-09-29 19:24 ` Peter Zijlstra
2021-09-29 19:45 ` Paul E. McKenney
2021-09-29 18:54 ` Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 09/11] context_tracking,livepatch: Dont disturb NOHZ_FULL Peter Zijlstra
2021-10-06 8:12 ` Petr Mladek
2021-10-06 9:04 ` Peter Zijlstra
2021-10-06 10:29 ` Petr Mladek
2021-10-06 11:41 ` Peter Zijlstra
2021-10-06 11:48 ` Miroslav Benes
2021-09-29 15:17 ` [RFC][PATCH v2 10/11] livepatch: Remove klp_synchronize_transition() Peter Zijlstra
2021-10-06 12:30 ` Petr Mladek
2021-09-29 15:17 ` [RFC][PATCH v2 11/11] context_tracking,x86: Fix text_poke_sync() vs NOHZ_FULL Peter Zijlstra
2021-10-21 18:39 ` Marcelo Tosatti
2021-10-21 18:40 ` Marcelo Tosatti
2021-10-21 19:25 ` Peter Zijlstra
2021-10-21 19:57 ` Marcelo Tosatti
2021-10-21 20:18 ` Peter Zijlstra
2021-10-26 18:19 ` Marcelo Tosatti
2021-10-26 19:38 ` Peter Zijlstra
2021-09-29 18:03 ` [PATCH v2 00/11] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL Paul E. McKenney
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