diff options
| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2024-12-03 11:35:58 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2024-12-05 14:25:28 +0100 |
| commit | 63a48181fbcddefe5fb4c6618938bb64c543945b (patch) | |
| tree | 203e7fa55596c828d847b37c6cf971c915ad1976 /kernel/smp.c | |
| parent | d387ceb17149fed4d85a1ec01b3d65ae0204060d (diff) | |
smp/scf: Evaluate local cond_func() before IPI side-effects
In smp_call_function_many_cond(), the local cond_func() is evaluated
after triggering the remote CPU IPIs.
If cond_func() depends on loading shared state updated by other CPU's
IPI handlers func(), then triggering execution of remote CPUs IPI before
evaluating cond_func() may have unexpected consequences.
One example scenario is evaluating a jiffies delay in cond_func(), which
is updated by func() in the IPI handlers. This situation can prevent
execution of periodic cleanup code on the local CPU.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20241203163558.3455535-1-mathieu.desnoyers@efficios.com
Diffstat (limited to 'kernel/smp.c')
| -rw-r--r-- | kernel/smp.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 27dc31a146a3..f104c8e83fc4 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -815,7 +815,8 @@ static void smp_call_function_many_cond(const struct cpumask *mask, WARN_ON_ONCE(!in_task()); /* Check if we need local execution. */ - if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask)) + if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask) && + (!cond_func || cond_func(this_cpu, info))) run_local = true; /* Check if we need remote execution, i.e., any CPU excluding this one. */ @@ -868,7 +869,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask, send_call_function_ipi_mask(cfd->cpumask_ipi); } - if (run_local && (!cond_func || cond_func(this_cpu, info))) { + if (run_local) { unsigned long flags; local_irq_save(flags); |