Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161194AbaKNNpU (ORCPT ); Fri, 14 Nov 2014 08:45:20 -0500 Received: from mga11.intel.com ([192.55.52.93]:11307 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935380AbaKNNpH (ORCPT ); Fri, 14 Nov 2014 08:45:07 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,386,1413270000"; d="scan'208";a="631966641" From: Alexander Shishkin To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Robert Richter , Frederic Weisbecker , Mike Galbraith , Paul Mackerras , Stephane Eranian , Andi Kleen , kan.liang@intel.com, adrian.hunter@intel.com, markus.t.metzger@intel.com, mathieu.poirier@linaro.org, acme@infradead.org, Alexander Shishkin Subject: [PATCH v8 05/14] perf: Add a pmu capability for "exclusive" events Date: Fri, 14 Nov 2014 15:43:38 +0200 Message-Id: <1415972627-37514-6-git-send-email-alexander.shishkin@linux.intel.com> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1415972627-37514-1-git-send-email-alexander.shishkin@linux.intel.com> References: <1415972627-37514-1-git-send-email-alexander.shishkin@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Usually, pmus that do, for example, instruction tracing, would only ever be able to have one event per task per cpu (or per perf_context). For such pmus it makes sense to disallow creating conflicting events early on, so as to provide consistent behavior for the user. This patch adds a pmu capability that indicates such constraint on event creation. Signed-off-by: Alexander Shishkin --- include/linux/perf_event.h | 1 + kernel/events/core.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index e7a15f5c3f..5c3dee021c 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -173,6 +173,7 @@ struct perf_event; #define PERF_PMU_CAP_NO_INTERRUPT 0x01 #define PERF_PMU_CAP_AUX_NO_SG 0x02 #define PERF_PMU_CAP_AUX_SW_DOUBLEBUF 0x04 +#define PERF_PMU_CAP_EXCLUSIVE 0x08 /** * struct pmu - generic performance monitoring unit diff --git a/kernel/events/core.c b/kernel/events/core.c index ac7bfb43fc..2399c12e49 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7298,6 +7298,32 @@ out: return ret; } +static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2) +{ + if ((e1->pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE) && + (e1->cpu == e2->cpu || + e1->cpu == -1 || + e2->cpu == -1)) + return true; + return false; +} + +static bool exclusive_event_ok(struct perf_event *event, + struct perf_event_context *ctx) +{ + struct perf_event *iter_event; + + if (!(event->pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE)) + return true; + + list_for_each_entry(iter_event, &ctx->event_list, event_entry) { + if (exclusive_event_match(iter_event, event)) + return false; + } + + return true; +} + /** * sys_perf_event_open - open a performance event, associate it to a task/cpu * @@ -7449,6 +7475,11 @@ SYSCALL_DEFINE5(perf_event_open, goto err_alloc; } + if ((pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE) && group_leader) { + err = -EBUSY; + goto err_context; + } + if (task) { put_task_struct(task); task = NULL; @@ -7534,6 +7565,12 @@ SYSCALL_DEFINE5(perf_event_open, } } + if (!exclusive_event_ok(event, ctx)) { + mutex_unlock(&ctx->mutex); + fput(event_file); + goto err_context; + } + perf_install_in_context(ctx, event, event->cpu); perf_unpin_context(ctx); mutex_unlock(&ctx->mutex); @@ -7620,6 +7657,14 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); + if (!exclusive_event_ok(event, ctx)) { + mutex_unlock(&ctx->mutex); + perf_unpin_context(ctx); + put_ctx(ctx); + err = -EBUSY; + goto err_free; + } + perf_install_in_context(ctx, event, cpu); perf_unpin_context(ctx); mutex_unlock(&ctx->mutex); -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/