Messages in this thread Patch in this message | | | Date | Thu, 31 Oct 2019 11:54:58 -0000 | From | "tip-bot2 for Joel Fernandes (Google)" <> | Subject | [tip: core/rcu] rcu: Ensure that ->rcu_urgent_qs is set before resched IPI |
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The following commit has been merged into the core/rcu branch of tip:
Commit-ID: 05ef9e9eb3dade21413680f41eb0170778e8ae2b Gitweb: https://git.kernel.org/tip/05ef9e9eb3dade21413680f41eb0170778e8ae2b Author: Joel Fernandes (Google) <joel@joelfernandes.org> AuthorDate: Thu, 15 Aug 2019 22:59:14 -04:00 Committer: Paul E. McKenney <paulmck@kernel.org> CommitterDate: Wed, 30 Oct 2019 08:34:35 -07:00
rcu: Ensure that ->rcu_urgent_qs is set before resched IPI
The RCU-specific resched_cpu() function sends a resched IPI to the specified CPU, which can be used to force the tick on for a given nohz_full CPU. This is needed when this nohz_full CPU is looping in the kernel while blocking the current grace period. However, for the tick to actually be forced on in all cases, that CPU's rcu_data structure's ->rcu_urgent_qs flag must be set beforehand. This commit therefore causes rcu_implicit_dynticks_qs() to set this flag prior to invoking resched_cpu() on a holdout nohz_full CPU.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/tree.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8110514..0d83b19 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1073,6 +1073,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) if (tick_nohz_full_cpu(rdp->cpu) && time_after(jiffies, READ_ONCE(rdp->last_fqs_resched) + jtsq * 3)) { + WRITE_ONCE(*ruqp, true); resched_cpu(rdp->cpu); WRITE_ONCE(rdp->last_fqs_resched, jiffies); }
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