diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2019-12-22 19:36:33 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-02-20 16:01:11 -0800 |
| commit | 8c9e0cb32315835825ea1ad725a858a2d2ce4a8e (patch) | |
| tree | 288fea8145ada762e4ae66a9b8df71448f04095d /kernel/rcu | |
| parent | 7ff8b4502bc0f576450d4ecbda97fa30e8002ed1 (diff) | |
srcu: Fix __call_srcu()/srcu_get_delay() datarace
The srcu_struct structure's ->srcu_gp_seq_needed_exp field is accessed
locklessly, so updates must use WRITE_ONCE(). This commit therefore
adds the needed WRITE_ONCE() invocations.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/srcutree.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index b1edac93e403..79848f7d575d 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -534,7 +534,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) rcu_seq_end(&ssp->srcu_gp_seq); gpseq = rcu_seq_current(&ssp->srcu_gp_seq); if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, gpseq)) - ssp->srcu_gp_seq_needed_exp = gpseq; + WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, gpseq); spin_unlock_irq_rcu_node(ssp); mutex_unlock(&ssp->srcu_gp_mutex); /* A new grace period can start at this point. But only one. */ @@ -614,7 +614,7 @@ static void srcu_funnel_exp_start(struct srcu_struct *ssp, struct srcu_node *snp } spin_lock_irqsave_rcu_node(ssp, flags); if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, s)) - ssp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, s); spin_unlock_irqrestore_rcu_node(ssp, flags); } @@ -674,7 +674,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, smp_store_release(&ssp->srcu_gp_seq_needed, s); /*^^^*/ } if (!do_norm && ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, s)) - ssp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, s); /* If grace period not already done and none in progress, start it. */ if (!rcu_seq_done(&ssp->srcu_gp_seq, s) && |