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| author | Paul E. McKenney <paulmck@kernel.org> | 2026-07-16 13:05:00 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2026-07-24 16:59:23 -0700 |
| commit | a050e671d3545cf1890ab764387958be6c542f6c (patch) | |
| tree | f03d17184e549ea3f1c0ebd7a6eb421ab221829e /kernel/rcu | |
| parent | d2282f9bc75ca39a8ea5b7fe87191609985aca30 (diff) | |
| download | linux-next-a050e671d3545cf1890ab764387958be6c542f6c.tar.gz linux-next-a050e671d3545cf1890ab764387958be6c542f6c.zip | |
rcu: Use WRITE_ONCE() for ->rcu_need_heavy_qs
Currently raw_cpu_write() is used to clear the ->rcu_need_heavy_qs
field of the per-CPU rcu_data structure. However, on x86 this is a
normal assignment, which does not play well with concurrent accesses.
This commit therefore upgrades the uses of raw_cpu_write() to its
concurrency-safe counterpart WRITE_ONCE() of an rdp pointer obtained
from this_cpu_ptr(&rcu_data).
KCSAN located this issue.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 03a43d3d2616..91d5b4dd08bf 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -357,9 +357,10 @@ bool rcu_watching_zero_in_eqs(int cpu, int *vp) */ notrace void rcu_momentary_eqs(void) { + struct rcu_data *rdp = this_cpu_ptr(&rcu_data); int seq; - raw_cpu_write(rcu_data.rcu_need_heavy_qs, false); + WRITE_ONCE(rdp->rcu_need_heavy_qs, false); seq = ct_state_inc(2 * CT_RCU_WATCHING); /* It is illegal to call this from idle state. */ WARN_ON_ONCE(!(seq & CT_RCU_WATCHING)); |