From c464c76eec4be587604ca082e8cded7e6b89f3bf Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Tue, 18 Mar 2014 16:56:41 +0800 Subject: [PATCH] perf: Allow building PMU drivers as modules This patch adds support for building PMU driver as module. It exports the functions perf_pmu_{register,unregister}() and adds reference tracking for the PMU driver module. When the PMU driver is built as a module, each active event of the PMU holds a reference to the driver module. Signed-off-by: Yan, Zheng Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1395133004-23205-1-git-send-email-zheng.z.yan@intel.com Cc: eranian@google.com Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 1 + kernel/events/core.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 3356abcfff18..af6dcf1d9e47 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -172,6 +172,7 @@ struct perf_event; struct pmu { struct list_head entry; + struct module *module; struct device *dev; const struct attribute_group **attr_groups; const char *name; diff --git a/kernel/events/core.c b/kernel/events/core.c index f83a71a3e46d..5129b1201050 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -39,6 +39,7 @@ #include #include #include +#include #include "internal.h" @@ -3229,6 +3230,9 @@ static void __free_event(struct perf_event *event) if (event->ctx) put_ctx(event->ctx); + if (event->pmu) + module_put(event->pmu->module); + call_rcu(&event->rcu_head, free_event_rcu); } static void free_event(struct perf_event *event) @@ -6551,6 +6555,7 @@ free_pdc: free_percpu(pmu->pmu_disable_count); goto unlock; } +EXPORT_SYMBOL_GPL(perf_pmu_register); void perf_pmu_unregister(struct pmu *pmu) { @@ -6572,6 +6577,7 @@ void perf_pmu_unregister(struct pmu *pmu) put_device(pmu->dev); free_pmu_context(pmu); } +EXPORT_SYMBOL_GPL(perf_pmu_unregister); struct pmu *perf_init_event(struct perf_event *event) { @@ -6585,6 +6591,10 @@ struct pmu *perf_init_event(struct perf_event *event) pmu = idr_find(&pmu_idr, event->attr.type); rcu_read_unlock(); if (pmu) { + if (!try_module_get(pmu->module)) { + pmu = ERR_PTR(-ENODEV); + goto unlock; + } event->pmu = pmu; ret = pmu->event_init(event); if (ret) @@ -6593,6 +6603,10 @@ struct pmu *perf_init_event(struct perf_event *event) } list_for_each_entry_rcu(pmu, &pmus, entry) { + if (!try_module_get(pmu->module)) { + pmu = ERR_PTR(-ENODEV); + goto unlock; + } event->pmu = pmu; ret = pmu->event_init(event); if (!ret) @@ -6771,6 +6785,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, err_pmu: if (event->destroy) event->destroy(event); + module_put(pmu->module); err_ns: if (event->ns) put_pid_ns(event->ns); -- 2.20.1