Patches 2 and 3 of https://lore.kernel.org/all/20241008183501.1354695-1-lucas.demarchi@xxxxxxxxx/ with the unused module var removed (pending for v2 after review). Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> --- include/linux/perf_event.h | 12 ++++++++++++ kernel/events/core.c | 37 ++++++++++++++++++++++++++++++++----- 2 files changed, 44 insertions(+), 5 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index fb908843f2092..d6983dbf5a45b 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -561,6 +561,17 @@ struct pmu { * Check period value for PERF_EVENT_IOC_PERIOD ioctl. */ int (*check_period) (struct perf_event *event, u64 value); /* optional */ + + /* + * Optional: get a reference. Typically needed by PMUs that are bound to a device + * that can be hotplugged, either physically or through sysfs' bind/unbind. When provided, + * pmu::put() is mandatory and it's driver responsibility to call perf_pmu_free() when + * resources can be released. + */ + struct pmu *(*get) (struct pmu *pmu); + + /* Optional: put a reference. See pmu::get() */ + void (*put) (struct pmu *pmu); }; enum perf_addr_filter_action_t { @@ -1104,6 +1115,7 @@ 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 void perf_pmu_free(struct pmu *pmu); extern void __perf_event_task_sched_in(struct task_struct *prev, struct task_struct *task); diff --git a/kernel/events/core.c b/kernel/events/core.c index 3b8b85adb10a9..2d39005ba6d9c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5319,6 +5319,20 @@ static void perf_pending_task_sync(struct perf_event *event) rcuwait_wait_event(&event->pending_work_wait, !event->pending_work, TASK_UNINTERRUPTIBLE); } +static void pmu_module_put(struct pmu **ppmu) +{ + struct pmu *pmu = *ppmu; + struct module *module = pmu->module; + + if (pmu->put) + pmu->put(pmu); + + module_put(module); + + /* Can't touch pmu anymore/ */ + *ppmu = NULL; +} + static void _free_event(struct perf_event *event) { irq_work_sync(&event->pending_irq); @@ -5374,7 +5388,8 @@ static void _free_event(struct perf_event *event) put_ctx(event->ctx); exclusive_event_destroy(event); - module_put(event->pmu->module); + + pmu_module_put(&event->pmu); call_rcu(&event->rcu_head, free_event_rcu); } @@ -11512,10 +11527,12 @@ static int perf_event_idx_default(struct perf_event *event) return 0; } -static void free_pmu_context(struct pmu *pmu) +void perf_pmu_free(struct pmu *pmu) { free_percpu(pmu->cpu_pmu_context); + free_percpu(pmu->pmu_disable_count); } +EXPORT_SYMBOL_GPL(perf_pmu_free); /* * Let userspace know that this PMU supports address range filtering: @@ -11749,6 +11766,11 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type) goto free_pdc; } + if (WARN_ONCE((!!pmu->get) ^ (!!pmu->put), "Can not register a pmu with only get or put defined.\n")) { + ret = -EINVAL; + goto free_pdc; + } + pmu->name = name; if (type >= 0) @@ -11845,7 +11867,6 @@ void perf_pmu_unregister(struct pmu *pmu) synchronize_srcu(&pmus_srcu); synchronize_rcu(); - free_percpu(pmu->pmu_disable_count); idr_remove(&pmu_idr, pmu->type); if (pmu_bus_running && pmu->dev && pmu->dev != PMU_NULL_DEV) { if (pmu->nr_addr_filters) @@ -11853,8 +11874,11 @@ void perf_pmu_unregister(struct pmu *pmu) device_del(pmu->dev); put_device(pmu->dev); } - free_pmu_context(pmu); + mutex_unlock(&pmus_lock); + + if (!pmu->put) + perf_pmu_free(pmu); } EXPORT_SYMBOL_GPL(perf_pmu_unregister); @@ -11888,6 +11912,9 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) BUG_ON(!ctx); } + if (pmu->get) + pmu->get(pmu); + event->pmu = pmu; ret = pmu->event_init(event); @@ -11924,7 +11951,7 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) } if (ret) - module_put(pmu->module); + pmu_module_put(&pmu); return ret; } -- 2.47.0
