From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759341AbZCWRZ3 (ORCPT ); Mon, 23 Mar 2009 13:25:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757209AbZCWRZM (ORCPT ); Mon, 23 Mar 2009 13:25:12 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:35503 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753257AbZCWRZK (ORCPT ); Mon, 23 Mar 2009 13:25:10 -0400 Message-Id: <20090323172417.152096433@chello.nl> References: <20090323172205.389341032@chello.nl> User-Agent: quilt/0.46-1 Date: Mon, 23 Mar 2009 18:22:07 +0100 From: Peter Zijlstra To: Paul Mackerras , Ingo Molnar Cc: linux-kernel@vger.kernel.org, Peter Zijlstra Subject: [PATCH 2/7] perf_counter: avoid recursion Content-Disposition: inline; filename=perf_counter-recursion.patch X-Bad-Reply: References but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- include/linux/perf_counter.h | 7 +++++++ kernel/perf_counter.c | 26 ++++++++++++++++++++++++++ 2 files changed, 33 insertions(+) Index: linux-2.6/include/linux/perf_counter.h =================================================================== --- linux-2.6.orig/include/linux/perf_counter.h +++ linux-2.6/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]; }; /* Index: linux-2.6/kernel/perf_counter.c =================================================================== --- linux-2.6.orig/kernel/perf_counter.c +++ linux-2.6/kernel/perf_counter.c @@ -23,6 +23,7 @@ #include #include #include +#include #include @@ -1532,10 +1533,31 @@ static void perf_swcounter_ctx_event(str 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 nr, nmi, regs); } + barrier(); + (*recursion)--; + +out: put_cpu_var(perf_cpu_context); } --