Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'perf_urgent_for_v6.7_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fix from Borislav Petkov:
- Make sure the context refcount is transferred too when migrating perf
events
* tag 'perf_urgent_for_v6.7_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix cpuctx refcounting
+25
-5
+8
-5
include/linux/perf_event.h
+8
-5
include/linux/perf_event.h
···
843
843
};
844
844
845
845
/*
846
-
* ,-----------------------[1:n]----------------------.
847
-
* V V
848
-
* perf_event_context <-[1:n]-> perf_event_pmu_context <--- perf_event
849
-
* ^ ^ | |
850
-
* `--------[1:n]---------' `-[n:1]-> pmu <-[1:n]-'
846
+
* ,-----------------------[1:n]------------------------.
847
+
* V V
848
+
* perf_event_context <-[1:n]-> perf_event_pmu_context <-[1:n]- perf_event
849
+
* | |
850
+
* `--[n:1]-> pmu <-[1:n]--'
851
851
*
852
852
*
853
853
* struct perf_event_pmu_context lifetime is refcount based and RCU freed
···
865
865
* ctx->mutex pinning the configuration. Since we hold a reference on
866
866
* group_leader (through the filedesc) it can't go away, therefore it's
867
867
* associated pmu_ctx must exist and cannot change due to ctx->mutex.
868
+
*
869
+
* perf_event holds a refcount on perf_event_context
870
+
* perf_event holds a refcount on perf_event_pmu_context
868
871
*/
869
872
struct perf_event_pmu_context {
870
873
struct pmu *pmu;
+17
kernel/events/core.c
+17
kernel/events/core.c
···
4828
4828
void *task_ctx_data = NULL;
4829
4829
4830
4830
if (!ctx->task) {
4831
+
/*
4832
+
* perf_pmu_migrate_context() / __perf_pmu_install_event()
4833
+
* relies on the fact that find_get_pmu_context() cannot fail
4834
+
* for CPU contexts.
4835
+
*/
4831
4836
struct perf_cpu_pmu_context *cpc;
4832
4837
4833
4838
cpc = per_cpu_ptr(pmu->cpu_pmu_context, event->cpu);
···
12894
12889
int cpu, struct perf_event *event)
12895
12890
{
12896
12891
struct perf_event_pmu_context *epc;
12892
+
struct perf_event_context *old_ctx = event->ctx;
12893
+
12894
+
get_ctx(ctx); /* normally find_get_context() */
12897
12895
12898
12896
event->cpu = cpu;
12899
12897
epc = find_get_pmu_context(pmu, ctx, event);
···
12905
12897
if (event->state >= PERF_EVENT_STATE_OFF)
12906
12898
event->state = PERF_EVENT_STATE_INACTIVE;
12907
12899
perf_install_in_context(ctx, event, cpu);
12900
+
12901
+
/*
12902
+
* Now that event->ctx is updated and visible, put the old ctx.
12903
+
*/
12904
+
put_ctx(old_ctx);
12908
12905
}
12909
12906
12910
12907
static void __perf_pmu_install(struct perf_event_context *ctx,
···
12948
12935
struct perf_event_context *src_ctx, *dst_ctx;
12949
12936
LIST_HEAD(events);
12950
12937
12938
+
/*
12939
+
* Since per-cpu context is persistent, no need to grab an extra
12940
+
* reference.
12941
+
*/
12951
12942
src_ctx = &per_cpu_ptr(&perf_cpu_context, src_cpu)->ctx;
12952
12943
dst_ctx = &per_cpu_ptr(&perf_cpu_context, dst_cpu)->ctx;
12953
12944