From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759782AbZCWU5b (ORCPT ); Mon, 23 Mar 2009 16:57:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757016AbZCWU5G (ORCPT ); Mon, 23 Mar 2009 16:57:06 -0400 Received: from hera.kernel.org ([140.211.167.34]:49063 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754411AbZCWU5E (ORCPT ); Mon, 23 Mar 2009 16:57:04 -0400 Date: Mon, 23 Mar 2009 20:56:31 GMT From: Peter Zijlstra To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20090323172417.152096433@chello.nl> References: <20090323172417.152096433@chello.nl> Subject: [tip:perfcounters/core] perf_counter: avoid recursion Message-ID: Git-Commit-ID: 4d0ec5f64b60057b395f2d314189ccde71d2d0bd X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Mon, 23 Mar 2009 20:56:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 4d0ec5f64b60057b395f2d314189ccde71d2d0bd Gitweb: http://git.kernel.org/tip/4d0ec5f64b60057b395f2d314189ccde71d2d0bd Author: Peter Zijlstra AuthorDate: Mon, 23 Mar 2009 18:22:07 +0100 Committer: Ingo Molnar CommitDate: Mon, 23 Mar 2009 21:45:09 +0100 perf_counter: avoid recursion Tracepoint events like lock_acquire and software counters like pagefaults can recurse into the perf counter code again, avoid that. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras LKML-Reference: <20090323172417.152096433@chello.nl> Signed-off-by: Ingo Molnar --- include/linux/perf_counter.h | 7 +++++++ kernel/perf_counter.c | 26 ++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 0 deletions(-) diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index 56099e5..18dc17d 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -328,6 +328,13 @@ struct perf_cpu_context { int active_oncpu; int max_pertask; int exclusive; + + /* + * Recursion avoidance: + * + * task, softirq, irq, nmi context + */ + int recursion[4]; }; /* diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index ca14fc4..ce34bff 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -23,6 +23,7 @@ #include #include #include +#include #include @@ -1532,10 +1533,31 @@ static void perf_swcounter_ctx_event(struct perf_counter_context *ctx, rcu_read_unlock(); } +static int *perf_swcounter_recursion_context(struct perf_cpu_context *cpuctx) +{ + if (in_nmi()) + return &cpuctx->recursion[3]; + + if (in_irq()) + return &cpuctx->recursion[2]; + + if (in_softirq()) + return &cpuctx->recursion[1]; + + return &cpuctx->recursion[0]; +} + static void __perf_swcounter_event(enum perf_event_types type, u32 event, u64 nr, int nmi, struct pt_regs *regs) { struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context); + int *recursion = perf_swcounter_recursion_context(cpuctx); + + if (*recursion) + goto out; + + (*recursion)++; + barrier(); perf_swcounter_ctx_event(&cpuctx->ctx, type, event, nr, nmi, regs); if (cpuctx->task_ctx) { @@ -1543,6 +1565,10 @@ static void __perf_swcounter_event(enum perf_event_types type, u32 event, nr, nmi, regs); } + barrier(); + (*recursion)--; + +out: put_cpu_var(perf_cpu_context); }