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| author | Peter Zijlstra <peterz@infradead.org> | 2024-10-25 11:21:41 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-04-08 21:55:48 +0300 |
| commit | da916e96e2dedcb2d40de77a7def833d315b81a6 (patch) | |
| tree | e5dac626e93b753a7a32b56f728e36c76def148a /include/linux | |
| parent | 4da0600edae1cf15d12bebacc66d7237e2c33fc6 (diff) | |
| download | linux-da916e96e2dedcb2d40de77a7def833d315b81a6.tar.xz | |
perf: Make perf_pmu_unregister() useable
Previously it was only safe to call perf_pmu_unregister() if there
were no active events of that pmu around -- which was impossible to
guarantee since it races all sorts against perf_init_event().
Rework the whole thing by:
- keeping track of all events for a given pmu
- 'hiding' the pmu from perf_init_event()
- waiting for the appropriate (s)rcu grace periods such that all
prior references to the PMU will be completed
- detaching all still existing events of that pmu (see first point)
and moving them to a new REVOKED state.
- actually freeing the pmu data.
Where notably the new REVOKED state must inhibit all event actions
from reaching code that wants to use event->pmu.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lkml.kernel.org/r/20250307193723.525402029@infradead.org
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/perf_event.h | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 0069ba6866a4..7f49a58b271d 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -325,6 +325,9 @@ struct perf_output_handle; struct pmu { struct list_head entry; + spinlock_t events_lock; + struct list_head events; + struct module *module; struct device *dev; struct device *parent; @@ -622,9 +625,10 @@ struct perf_addr_filter_range { * enum perf_event_state - the states of an event: */ enum perf_event_state { - PERF_EVENT_STATE_DEAD = -4, - PERF_EVENT_STATE_EXIT = -3, - PERF_EVENT_STATE_ERROR = -2, + PERF_EVENT_STATE_DEAD = -5, + PERF_EVENT_STATE_REVOKED = -4, /* pmu gone, must not touch */ + PERF_EVENT_STATE_EXIT = -3, /* task died, still inherit */ + PERF_EVENT_STATE_ERROR = -2, /* scheduling error, can enable */ PERF_EVENT_STATE_OFF = -1, PERF_EVENT_STATE_INACTIVE = 0, PERF_EVENT_STATE_ACTIVE = 1, @@ -865,6 +869,7 @@ struct perf_event { void *security; #endif struct list_head sb_list; + struct list_head pmu_list; /* * Certain events gets forwarded to another pmu internally by over- @@ -1155,7 +1160,7 @@ extern void perf_aux_output_flag(struct perf_output_handle *handle, u64 flags); extern void perf_event_itrace_started(struct perf_event *event); extern int perf_pmu_register(struct pmu *pmu, const char *name, int type); -extern void perf_pmu_unregister(struct pmu *pmu); +extern int perf_pmu_unregister(struct pmu *pmu); extern void __perf_event_task_sched_in(struct task_struct *prev, struct task_struct *task); @@ -1760,7 +1765,7 @@ static inline bool needs_branch_stack(struct perf_event *event) static inline bool has_aux(struct perf_event *event) { - return event->pmu->setup_aux; + return event->pmu && event->pmu->setup_aux; } static inline bool has_aux_action(struct perf_event *event) |