diff options
| author | Thomas Richter <tmricht@linux.ibm.com> | 2026-09-08 12:56:37 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-09-10 10:22:50 +0200 |
| commit | 59e63416f5153e7d58652c616fbdcb7d5e01fff7 (patch) | |
| tree | 33f37a5a5c86a8b200642bf8ef383ff7a89b9b61 | |
| parent | df2908090cda368b01ff43709f51890076c56157 (diff) | |
| download | linux-next-59e63416f5153e7d58652c616fbdcb7d5e01fff7.tar.gz linux-next-59e63416f5153e7d58652c616fbdcb7d5e01fff7.zip | |
perf/core: Allow list_del during perf_event_overflow()
A PMU might use perf_sched_cb_inc() and perf_sched_cb_dec()
interface to get the PMU call back function pmu::sched_task
invoked at schedule in and schedule out. This is achieved
by walking along the list anchored by sched_cb_list.
The following scenario might lead to a list corruption.
perf_pmu_sched_task()
for_each_list_entry(..., &sched_cb_list)
+--> __perf_pmu_sched_task()
+--> event->pmu->sched_task())
+--> PMU_push_sample()
+--> perf_event_overflow()
+--> __perf_event_overflow()
+--> pmu->stop()
+--> perf_sched_cb_dec()
remove entry from sched_cb_list
while list node in use.
This happens when ioctl(fd, PERF_EVENT_IOC_REFRESH, xxx) has been
invoked and perf_event::event_limit hits zero.
Prevent the list corruption and convert for_each_list_entry()
to for_each_list_entry_safe().
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260908105637.627004-1-tmricht@linux.ibm.com
| -rw-r--r-- | kernel/events/core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 33210aff3ee6..fe33fe15689d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3925,13 +3925,13 @@ static void perf_pmu_sched_task(struct task_struct *prev, bool sched_in) { struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context); - struct perf_cpu_pmu_context *cpc; + struct perf_cpu_pmu_context *cpc, *cpc2; /* cpuctx->task_ctx will be handled in perf_event_context_sched_in/out */ if (prev == next || cpuctx->task_ctx) return; - list_for_each_entry(cpc, this_cpu_ptr(&sched_cb_list), sched_cb_entry) + list_for_each_entry_safe(cpc, cpc2, this_cpu_ptr(&sched_cb_list), sched_cb_entry) __perf_pmu_sched_task(cpc, sched_in ? next : prev, sched_in); } |