diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2024-10-09 11:00:45 -0700 |
|---|---|---|
| committer | Frederic Weisbecker <frederic@kernel.org> | 2024-11-12 21:45:14 +0100 |
| commit | d4e287d7caff971c859ee6db65add42bde1d86ec (patch) | |
| tree | bada783bb1502a692fe9defb87fa6b229dd3d9cc /kernel/rcu | |
| parent | 0a116dc86d18ba109090be1af1641ef1d57f4e20 (diff) | |
rcu-tasks: Remove open-coded one-byte cmpxchg() emulation
This commit removes the open-coded one-byte cmpxchg() emulation from
rcu_trc_cmpxchg_need_qs(), replacing it with just cmpxchg() given the
latter's new-found ability to handle single-byte arguments across all
architectures.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tasks.h | 17 |
1 files changed, 1 insertions, 16 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index dd9730fd44fb..c789d994e7eb 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1541,22 +1541,7 @@ static void rcu_st_need_qs(struct task_struct *t, u8 v) */ u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new) { - union rcu_special ret; - union rcu_special trs_old = READ_ONCE(t->trc_reader_special); - union rcu_special trs_new = trs_old; - - if (trs_old.b.need_qs != old) - return trs_old.b.need_qs; - trs_new.b.need_qs = new; - - // Although cmpxchg() appears to KCSAN to update all four bytes, - // only the .b.need_qs byte actually changes. - instrument_atomic_read_write(&t->trc_reader_special.b.need_qs, - sizeof(t->trc_reader_special.b.need_qs)); - // Avoid false-positive KCSAN failures. - ret.s = data_race(cmpxchg(&t->trc_reader_special.s, trs_old.s, trs_new.s)); - - return ret.b.need_qs; + return cmpxchg(&t->trc_reader_special.b.need_qs, old, new); } EXPORT_SYMBOL_GPL(rcu_trc_cmpxchg_need_qs); |