From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754508AbdBET1V (ORCPT + 2 others); Sun, 5 Feb 2017 14:27:21 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:28363 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753625AbdBET1S (ORCPT ); Sun, 5 Feb 2017 14:27:18 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Peter Zijlstra , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Ingo Molnar , Willy Tarreau Subject: [PATCH 3.10 211/319] perf: Tighten (and fix) the grouping condition Date: Sun, 5 Feb 2017 20:20:33 +0100 Message-Id: <1486322541-8206-112-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322541-8206-1-git-send-email-w@1wt.eu> References: <1486322541-8206-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Peter Zijlstra commit c3c87e770458aa004bd7ed3f29945ff436fd6511 upstream. The fix from 9fc81d87420d ("perf: Fix events installation during moving group") was incomplete in that it failed to recognise that creating a group with events for different CPUs is semantically broken -- they cannot be co-scheduled. Furthermore, it leads to real breakage where, when we create an event for CPU Y and then migrate it to form a group on CPU X, the code gets confused where the counter is programmed -- triggered in practice as well by me via the perf fuzzer. Fix this by tightening the rules for creating groups. Only allow grouping of counters that can be co-scheduled in the same context. This means for the same task and/or the same cpu. Fixes: 9fc81d87420d ("perf: Fix events installation during moving group") Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20150123125834.090683288@infradead.org Signed-off-by: Ingo Molnar Signed-off-by: Willy Tarreau --- include/linux/perf_event.h | 6 ------ kernel/events/core.c | 15 +++++++++++++-- 2 files changed, 13 insertions(+), 8 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 229a757..3204422 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -430,11 +430,6 @@ struct perf_event { #endif /* CONFIG_PERF_EVENTS */ }; -enum perf_event_context_type { - task_context, - cpu_context, -}; - /** * struct perf_event_context - event context structure * @@ -442,7 +437,6 @@ enum perf_event_context_type { */ struct perf_event_context { struct pmu *pmu; - enum perf_event_context_type type; /* * Protect the states of the events in the list, * nr_active, and the list: diff --git a/kernel/events/core.c b/kernel/events/core.c index 0f52078..76e26b8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6249,7 +6249,6 @@ skip_type: __perf_event_init_context(&cpuctx->ctx); lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex); lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock); - cpuctx->ctx.type = cpu_context; cpuctx->ctx.pmu = pmu; cpuctx->jiffies_interval = 1; INIT_LIST_HEAD(&cpuctx->rotation_list); @@ -6856,7 +6855,19 @@ SYSCALL_DEFINE5(perf_event_open, * task or CPU context: */ if (move_group) { - if (group_leader->ctx->type != ctx->type) + /* + * Make sure we're both on the same task, or both + * per-cpu events. + */ + if (group_leader->ctx->task != ctx->task) + goto err_context; + + /* + * Make sure we're both events for the same CPU; + * grouping events for different CPUs is broken; since + * you can never concurrently schedule them anyhow. + */ + if (group_leader->cpu != event->cpu) goto err_context; } else { if (group_leader->ctx != ctx) -- 2.8.0.rc2.1.gbe9624a