Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752655Ab3FWNr0 (ORCPT ); Sun, 23 Jun 2013 09:47:26 -0400 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:47883 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752022Ab3FWNrV (ORCPT ); Sun, 23 Jun 2013 09:47:21 -0400 From: "Srivatsa S. Bhat" Subject: [PATCH 27/45] perf/x86: Use get/put_online_cpus_atomic() to prevent CPU offline To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Thomas Gleixner , "H. Peter Anvin" , x86@kernel.org Date: Sun, 23 Jun 2013 19:13:54 +0530 Message-ID: <20130623134350.19094.73767.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> References: <20130623133642.19094.16038.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062313-7014-0000-0000-000003376DE7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2257 Lines: 66 The CPU_DYING notifier modifies the per-cpu pointer pmu->box, and this can race with functions such as uncore_pmu_to_box() and uncore_pci_remove() when we remove stop_machine() from the CPU offline path. So protect them using get/put_online_cpus_atomic(). Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: x86@kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/x86/kernel/cpu/perf_event_intel_uncore.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c index 9dd9975..7c2a064 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c @@ -1,3 +1,4 @@ +#include #include "perf_event_intel_uncore.h" static struct intel_uncore_type *empty_uncore[] = { NULL, }; @@ -2630,6 +2631,7 @@ uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu) if (box) return box; + get_online_cpus_atomic(); raw_spin_lock(&uncore_box_lock); list_for_each_entry(box, &pmu->box_list, list) { if (box->phys_id == topology_physical_package_id(cpu)) { @@ -2639,6 +2641,7 @@ uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu) } } raw_spin_unlock(&uncore_box_lock); + put_online_cpus_atomic(); return *per_cpu_ptr(pmu->box, cpu); } @@ -3229,6 +3232,7 @@ static void uncore_pci_remove(struct pci_dev *pdev) list_del(&box->list); raw_spin_unlock(&uncore_box_lock); + get_online_cpus_atomic(); for_each_possible_cpu(cpu) { if (*per_cpu_ptr(pmu->box, cpu) == box) { *per_cpu_ptr(pmu->box, cpu) = NULL; @@ -3237,6 +3241,8 @@ static void uncore_pci_remove(struct pci_dev *pdev) } WARN_ON_ONCE(atomic_read(&box->refcnt) != 1); + put_online_cpus_atomic(); + kfree(box); } -- 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/