diff options
Diffstat (limited to 'debian/patches-rt/0003-perf-Remove-perf_swevent_get_recursion_context-from-.patch')
| -rw-r--r-- | debian/patches-rt/0003-perf-Remove-perf_swevent_get_recursion_context-from-.patch | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/debian/patches-rt/0003-perf-Remove-perf_swevent_get_recursion_context-from-.patch b/debian/patches-rt/0003-perf-Remove-perf_swevent_get_recursion_context-from-.patch new file mode 100644 index 000000000..150b5530d --- /dev/null +++ b/debian/patches-rt/0003-perf-Remove-perf_swevent_get_recursion_context-from-.patch @@ -0,0 +1,55 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Tue, 12 Mar 2024 19:01:51 +0100 +Subject: [PATCH 3/4] perf: Remove perf_swevent_get_recursion_context() from + perf_pending_task(). +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz + +perf_swevent_get_recursion_context() is supposed to avoid recursion. +This requires to remain on the same CPU in order to decrement/ increment +the same counter. This is done by using preempt_disable(). Having +preemption disabled while sending a signal leads to locking problems on +PREEMPT_RT because sighand, a spinlock_t, becomes a sleeping lock. + +This callback runs in task context and currently delivers only a signal +to "itself". Any kind of recusrion protection in this context is not +required. + +Remove recursion protection in perf_pending_task(). + +Tested-by: Marco Elver <elver@google.com> +Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> +Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> +Link: https://lore.kernel.org/r/20240312180814.3373778-4-bigeasy@linutronix.de +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/events/core.c | 12 ------------ + 1 file changed, 12 deletions(-) + +--- a/kernel/events/core.c ++++ b/kernel/events/core.c +@@ -6785,14 +6785,6 @@ static void perf_pending_irq(struct irq_ + static void perf_pending_task(struct callback_head *head) + { + struct perf_event *event = container_of(head, struct perf_event, pending_task); +- int rctx; +- +- /* +- * If we 'fail' here, that's OK, it means recursion is already disabled +- * and we won't recurse 'further'. +- */ +- preempt_disable_notrace(); +- rctx = perf_swevent_get_recursion_context(); + + if (event->pending_work) { + event->pending_work = 0; +@@ -6800,10 +6792,6 @@ static void perf_pending_task(struct cal + local_dec(&event->ctx->nr_pending); + } + +- if (rctx >= 0) +- perf_swevent_put_recursion_context(rctx); +- preempt_enable_notrace(); +- + put_event(event); + } + |