diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2024-03-07 20:11:21 -0800 |
|---|---|---|
| committer | Uladzislau Rezki (Sony) <urezki@gmail.com> | 2024-04-15 16:28:46 +0200 |
| commit | a542d116bab28b4bcade2f41488f4617373c620f (patch) | |
| tree | f0556d1ed06a432bc609ccdb7697ae47a30facae /kernel/rcu | |
| parent | c90b9e49782424623e0006abbcab98f835c1f1d8 (diff) | |
rcu: Mark writes to rcu_sync ->gp_count field
The rcu_sync structure's ->gp_count field is updated under the protection
of ->rss_lock, but read locklessly, and KCSAN noted the data race.
This commit therefore uses WRITE_ONCE() to do this update to clearly
document its racy nature.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/sync.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c index 86df878a2fee..6c2bd9001adc 100644 --- a/kernel/rcu/sync.c +++ b/kernel/rcu/sync.c @@ -122,7 +122,7 @@ void rcu_sync_enter(struct rcu_sync *rsp) * we are called at early boot time but this shouldn't happen. */ } - rsp->gp_count++; + WRITE_ONCE(rsp->gp_count, rsp->gp_count + 1); spin_unlock_irq(&rsp->rss_lock); if (gp_state == GP_IDLE) { @@ -151,11 +151,15 @@ void rcu_sync_enter(struct rcu_sync *rsp) */ void rcu_sync_exit(struct rcu_sync *rsp) { + int gpc; + WARN_ON_ONCE(READ_ONCE(rsp->gp_state) == GP_IDLE); WARN_ON_ONCE(READ_ONCE(rsp->gp_count) == 0); spin_lock_irq(&rsp->rss_lock); - if (!--rsp->gp_count) { + gpc = rsp->gp_count - 1; + WRITE_ONCE(rsp->gp_count, gpc); + if (!gpc) { if (rsp->gp_state == GP_PASSED) { WRITE_ONCE(rsp->gp_state, GP_EXIT); rcu_sync_call(rsp); |