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authorLinus Torvalds <torvalds@linux-foundation.org>2022-01-30 15:02:32 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-30 15:02:32 +0200
commit27a96c4feb837093f6075bbd97c942260d26ef33 (patch)
treeaa125b46d7101bf0c02361af6271fe2cb31e1fd3
parent24f4db1f3a2725a6308105081d822b26889e1018 (diff)
parentc5de60cd622a2607c043ba65e25a6e9998a369f9 (diff)
downloadlwn-27a96c4feb837093f6075bbd97c942260d26ef33.tar.gz
lwn-27a96c4feb837093f6075bbd97c942260d26ef33.zip
Merge tag 'perf_urgent_for_v5.17_rc2_p2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Borislav Petkov: - Prevent accesses to the per-CPU cgroup context list from another CPU except the one it belongs to, to avoid list corruption - Make sure parent events are always woken up to avoid indefinite hangs in the traced workload * tag 'perf_urgent_for_v5.17_rc2_p2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/core: Fix cgroup event list management perf: Always wake the parent event
-rw-r--r--kernel/events/core.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 479c9e672ec4..76c754e45d01 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2462,7 +2462,11 @@ static void perf_remove_from_context(struct perf_event *event, unsigned long fla
* event_function_call() user.
*/
raw_spin_lock_irq(&ctx->lock);
- if (!ctx->is_active) {
+ /*
+ * Cgroup events are per-cpu events, and must IPI because of
+ * cgrp_cpuctx_list.
+ */
+ if (!ctx->is_active && !is_cgroup_event(event)) {
__perf_remove_from_context(event, __get_cpu_context(ctx),
ctx, (void *)flags);
raw_spin_unlock_irq(&ctx->lock);
@@ -2895,11 +2899,14 @@ perf_install_in_context(struct perf_event_context *ctx,
* perf_event_attr::disabled events will not run and can be initialized
* without IPI. Except when this is the first event for the context, in
* that case we need the magic of the IPI to set ctx->is_active.
+ * Similarly, cgroup events for the context also needs the IPI to
+ * manipulate the cgrp_cpuctx_list.
*
* The IOC_ENABLE that is sure to follow the creation of a disabled
* event will issue the IPI and reprogram the hardware.
*/
- if (__perf_effective_state(event) == PERF_EVENT_STATE_OFF && ctx->nr_events) {
+ if (__perf_effective_state(event) == PERF_EVENT_STATE_OFF &&
+ ctx->nr_events && !is_cgroup_event(event)) {
raw_spin_lock_irq(&ctx->lock);
if (ctx->task == TASK_TOMBSTONE) {
raw_spin_unlock_irq(&ctx->lock);
@@ -5985,6 +5992,8 @@ static void ring_buffer_attach(struct perf_event *event,
struct perf_buffer *old_rb = NULL;
unsigned long flags;
+ WARN_ON_ONCE(event->parent);
+
if (event->rb) {
/*
* Should be impossible, we set this when removing
@@ -6042,6 +6051,9 @@ static void ring_buffer_wakeup(struct perf_event *event)
{
struct perf_buffer *rb;
+ if (event->parent)
+ event = event->parent;
+
rcu_read_lock();
rb = rcu_dereference(event->rb);
if (rb) {
@@ -6055,6 +6067,9 @@ struct perf_buffer *ring_buffer_get(struct perf_event *event)
{
struct perf_buffer *rb;
+ if (event->parent)
+ event = event->parent;
+
rcu_read_lock();
rb = rcu_dereference(event->rb);
if (rb) {
@@ -6763,7 +6778,7 @@ static unsigned long perf_prepare_sample_aux(struct perf_event *event,
if (WARN_ON_ONCE(READ_ONCE(sampler->oncpu) != smp_processor_id()))
goto out;
- rb = ring_buffer_get(sampler->parent ? sampler->parent : sampler);
+ rb = ring_buffer_get(sampler);
if (!rb)
goto out;
@@ -6829,7 +6844,7 @@ static void perf_aux_sample_output(struct perf_event *event,
if (WARN_ON_ONCE(!sampler || !data->aux_size))
return;
- rb = ring_buffer_get(sampler->parent ? sampler->parent : sampler);
+ rb = ring_buffer_get(sampler);
if (!rb)
return;