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authorNeeraj Upadhyay <neeraju@codeaurora.org>2021-08-18 13:34:00 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-11-18 19:16:23 +0100
commit4a9334d04ba646e6e5d9e242c0836c2acf475dd9 (patch)
tree99fbe1cc137bd50f740f269470136c65f66ac9a5 /kernel/rcu
parent3998e06d9511d639892f9f515c3a50f7591ff1ba (diff)
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rcu: Fix existing exp request check in sync_sched_exp_online_cleanup()
[ Upstream commit f0b2b2df5423fb369ac762c77900bc7765496d58 ] The sync_sched_exp_online_cleanup() checks to see if RCU needs an expedited quiescent state from the incoming CPU, sending it an IPI if so. Before sending IPI, it checks whether expedited qs need has been already requested for the incoming CPU, by checking rcu_data.cpu_no_qs.b.exp for the current cpu, on which sync_sched_exp_online_cleanup() is running. This works for the case where incoming CPU is same as self. However, for the case where incoming CPU is different from self, expedited request won't get marked, which can potentially delay reporting of expedited quiescent state for the incoming CPU. Fixes: e015a3411220 ("rcu: Avoid self-IPI in sync_sched_exp_online_cleanup()") Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree_exp.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 2796084ef85a..454b516ea566 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -760,7 +760,7 @@ static void sync_sched_exp_online_cleanup(int cpu)
my_cpu = get_cpu();
/* Quiescent state either not needed or already requested, leave. */
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
- __this_cpu_read(rcu_data.cpu_no_qs.b.exp)) {
+ rdp->cpu_no_qs.b.exp) {
put_cpu();
return;
}