From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 06/19] srcu: Add data_race() to ->srcu_lock_count and ->srcu_unlock_count arrays
Date: Wed, 15 Apr 2020 10:10:41 -0700 [thread overview]
Message-ID: <20200415171054.9013-6-paulmck@kernel.org> (raw)
In-Reply-To: <20200415171017.GA7821@paulmck-ThinkPad-P72>
From: "Paul E. McKenney" <paulmck@kernel.org>
The srcu_data structure's ->srcu_lock_count and ->srcu_unlock_count arrays
are read and written locklessly, so this commit adds the data_race()
to the diagnostic-print loads from these arrays in order mark them as
known and approved data-racy accesses.
This data race was reported by KCSAN. Not appropriate for backporting due
to failure being unlikely and due to this being used only by rcutorture.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/srcutree.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index ba2b751..6d3ef70 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1281,8 +1281,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf)
struct srcu_data *sdp;
sdp = per_cpu_ptr(ssp->sda, cpu);
- u0 = sdp->srcu_unlock_count[!idx];
- u1 = sdp->srcu_unlock_count[idx];
+ u0 = data_race(sdp->srcu_unlock_count[!idx]);
+ u1 = data_race(sdp->srcu_unlock_count[idx]);
/*
* Make sure that a lock is always counted if the corresponding
@@ -1290,8 +1290,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf)
*/
smp_rmb();
- l0 = sdp->srcu_lock_count[!idx];
- l1 = sdp->srcu_lock_count[idx];
+ l0 = data_race(sdp->srcu_lock_count[!idx]);
+ l1 = data_race(sdp->srcu_lock_count[idx]);
c0 = l0 - u0;
c1 = l1 - u1;
--
2.9.5
next prev parent reply other threads:[~2020-04-15 17:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 17:10 [PATCH tip/core/rcu 0/19] Miscellaneous fixes for v5.8 Paul E. McKenney
2020-04-15 17:10 ` [PATCH tip/core/rcu 01/19] rcu: Add KCSAN stubs paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 02/19] srcu: " paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 03/19] rcu: Mark rcu_state.ncpus to detect concurrent writes paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 04/19] rcu: Add *_ONCE() and data_race() to rcu_node ->exp_tasks plus locking paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 05/19] rcu: Add READ_ONCE and data_race() to rcu_node ->boost_tasks paulmck
2020-04-15 17:10 ` paulmck [this message]
2020-04-15 17:10 ` [PATCH tip/core/rcu 07/19] rcu: Add WRITE_ONCE() " paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 08/19] rcu: Use data_race() for RCU CPU stall-warning prints paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 09/19] drm: Make drm_dp_mst_dsc_aux_for_port() safe for old compilers paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 10/19] rcu: Expedite first two FQS scans under callback-overload conditions paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 11/19] rcu: Fix the (t=0 jiffies) false positive paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 12/19] Revert "rculist: Describe variadic macro argument in a Sphinx-compatible way" paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 13/19] rcu: Get rid of some doc warnings in update.c paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 14/19] rcu: Mark rcu_state.gp_seq to detect more concurrent writes paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 15/19] rcu: Replace assigned pointer ret value by corresponding boolean value paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 16/19] rcu: Replace 1 by true paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 17/19] rcu: Convert ULONG_CMP_GE() to time_after() for jiffy comparison paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 18/19] rcu: Convert rcu_initiate_boost() ULONG_CMP_GE() to time_after() paulmck
2020-04-15 17:10 ` [PATCH tip/core/rcu 19/19] rcu: Convert rcu_nohz_full_cpu() ULONG_CMP_LT() to time_before() paulmck
2020-04-15 17:21 ` [PATCH tip/core/rcu 0/19] Miscellaneous fixes for v5.8 Andrew Morton
2020-04-15 17:32 ` Paul E. McKenney
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