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From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	hpa@zytor.com, tglx@linutronix.de, mingo@kernel.org,
	bigeasy@linutronix.de
Subject: [tip:smp/hotplug] perf: Reorder cpu hotplug rwsem against cred_guard_mutex
Date: Mon, 1 May 2017 05:57:53 -0700
Message-ID: <tip-1526eee294dd52b70804aa377579682cc4dcd9ad@git.kernel.org> (raw)
In-Reply-To: <20170428142456.5xh44ef3fv7w2kkh@linutronix.de>

Commit-ID:  1526eee294dd52b70804aa377579682cc4dcd9ad
Gitweb:     http://git.kernel.org/tip/1526eee294dd52b70804aa377579682cc4dcd9ad
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 1 May 2017 14:35:45 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 1 May 2017 14:54:40 +0200

perf: Reorder cpu hotplug rwsem against cred_guard_mutex

sys_perf_event_open() takes the hotplug rwsem before the
cred_guard_mutex. The exit() path has the reverse lock order.

The hotplug protection in sys_perf_event_open() is not required before
taking the cred_guard_mutex, so it can be reordered there.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/20170428142456.5xh44ef3fv7w2kkh@linutronix.de
---
 kernel/events/core.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 997123c..71d8c74 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9742,12 +9742,10 @@ SYSCALL_DEFINE5(perf_event_open,
 		goto err_task;
 	}
 
-	get_online_cpus();
-
 	if (task) {
 		err = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
 		if (err)
-			goto err_cpus;
+			goto err_task;
 
 		/*
 		 * Reuse ptrace permission checks for now.
@@ -9765,11 +9763,13 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (flags & PERF_FLAG_PID_CGROUP)
 		cgroup_fd = pid;
 
+	get_online_cpus();
+
 	event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
 				 NULL, NULL, cgroup_fd);
 	if (IS_ERR(event)) {
 		err = PTR_ERR(event);
-		goto err_cred;
+		goto err_cpus;
 	}
 
 	if (is_sampling_event(event)) {
@@ -10017,13 +10017,13 @@ SYSCALL_DEFINE5(perf_event_open,
 		perf_event_ctx_unlock(group_leader, gctx);
 	mutex_unlock(&ctx->mutex);
 
+	put_online_cpus();
+
 	if (task) {
 		mutex_unlock(&task->signal->cred_guard_mutex);
 		put_task_struct(task);
 	}
 
-	put_online_cpus();
-
 	mutex_lock(&current->perf_event_mutex);
 	list_add_tail(&event->owner_entry, &current->perf_event_list);
 	mutex_unlock(&current->perf_event_mutex);
@@ -10054,11 +10054,11 @@ err_alloc:
 	 */
 	if (!event_file)
 		free_event(event);
+err_cpus:
+	put_online_cpus();
 err_cred:
 	if (task)
 		mutex_unlock(&task->signal->cred_guard_mutex);
-err_cpus:
-	put_online_cpus();
 err_task:
 	if (task)
 		put_task_struct(task);

  parent reply index

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-18 17:04 [patch V2 00/24] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Thomas Gleixner
2017-04-18 17:04 ` [patch V2 01/24] cpu/hotplug: Provide cpuhp_setup/remove_state[_nocalls]_cpuslocked() Thomas Gleixner
2017-04-20 11:18   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 02/24] stop_machine: Provide stop_machine_cpuslocked() Thomas Gleixner
2017-04-20 11:19   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 03/24] padata: Make padata_alloc() static Thomas Gleixner
2017-04-20 11:19   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-04-18 17:04 ` [patch V2 04/24] padata: Avoid nested calls to get_online_cpus() in pcrypt_init_padata() Thomas Gleixner
2017-04-20 11:20   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 05/24] x86/mtrr: Remove get_online_cpus() from mtrr_save_state() Thomas Gleixner
2017-04-20 11:20   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 06/24] cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner
2017-04-20 11:21   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 07/24] KVM/PPC/Book3S HV: " Thomas Gleixner
2017-04-20 11:21   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 08/24] hwtracing/coresight-etm3x: " Thomas Gleixner
2017-04-20 11:22   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-20 15:14   ` [patch V2 08/24] " Mathieu Poirier
2017-04-20 15:32   ` Mathieu Poirier
2017-04-18 17:04 ` [patch V2 09/24] hwtracing/coresight-etm4x: " Thomas Gleixner
2017-04-20 11:22   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 10/24] perf/x86/intel/cqm: Use cpuhp_setup_state_cpuslocked() Thomas Gleixner
2017-04-20 11:23   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 11/24] ARM/hw_breakpoint: " Thomas Gleixner
2017-04-19 17:54   ` Mark Rutland
2017-04-19 18:20     ` Thomas Gleixner
2017-04-20 11:23   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 12/24] s390/kernel: Use stop_machine_cpuslocked() Thomas Gleixner
2017-04-20 11:24   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 13/24] powerpc/powernv: " Thomas Gleixner
2017-04-20 11:24   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 14/24] cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu() Thomas Gleixner
2017-04-20 11:25   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 15/24] x86/perf: Drop EXPORT of perf_check_microcode Thomas Gleixner
2017-04-20 11:25   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-04-18 17:04 ` [patch V2 16/24] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() Thomas Gleixner
2017-04-20 11:26   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-04-18 17:04 ` [patch V2 17/24] PCI: Use cpu_hotplug_disable() instead of get_online_cpus() Thomas Gleixner
2017-04-20 11:27   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-04-18 17:05 ` [patch V2 18/24] PCI: Replace the racy recursion prevention Thomas Gleixner
2017-04-20 11:27   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-04-18 17:05 ` [patch V2 19/24] ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() Thomas Gleixner
2017-04-20 11:28   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-04-18 17:05 ` [patch V2 20/24] perf/core: Remove redundant get_online_cpus() Thomas Gleixner
2017-04-20 11:28   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-04-18 17:05 ` [patch V2 21/24] jump_label: Pull get_online_cpus() into generic code Thomas Gleixner
2017-04-18 17:05 ` [patch V2 22/24] jump_label: Provide static_key_slow_inc_cpuslocked() Thomas Gleixner
2017-04-18 17:05 ` [patch V2 23/24] perf: Avoid cpu_hotplug_lock r-r recursion Thomas Gleixner
2017-04-18 17:05 ` [patch V2 24/24] cpu/hotplug: Convert hotplug locking to percpu rwsem Thomas Gleixner
2017-04-20 11:30   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-10  4:59   ` [patch V2 24/24] " Michael Ellerman
2017-05-10  8:49     ` Thomas Gleixner
2017-05-10 16:30       ` Steven Rostedt
2017-05-10 17:15         ` Steven Rostedt
2017-05-11  5:49       ` Michael Ellerman
2017-04-25 16:10 ` [patch V2 00/24] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Mark Rutland
2017-04-25 17:28   ` Sebastian Siewior
2017-04-26  8:59     ` Mark Rutland
2017-04-26  9:40       ` Suzuki K Poulose
2017-04-26 10:32         ` Mark Rutland
2017-04-27  8:27           ` Sebastian Siewior
2017-04-27  9:57             ` Mark Rutland
2017-04-27 10:01               ` Thomas Gleixner
2017-04-27 12:30                 ` Mark Rutland
2017-04-27 15:48                   ` [PATCH] arm64: cpufeature: use static_branch_enable_cpuslocked() (was: Re: [patch V2 00/24] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem) Mark Rutland
2017-04-27 16:35                     ` Suzuki K Poulose
2017-04-27 17:03                       ` [PATCH] arm64: cpufeature: use static_branch_enable_cpuslocked() Suzuki K Poulose
2017-04-27 17:17                         ` Mark Rutland
2017-04-28 14:24 ` [RFC PATCH] trace/perf: cure locking issue in perf_event_open() error path Sebastian Siewior
2017-04-28 14:27   ` Sebastian Siewior
2017-05-01 12:57   ` tip-bot for Thomas Gleixner [this message]
2017-05-01 12:58   ` [tip:smp/hotplug] perf: Push hotplug protection down to callers tip-bot for Thomas Gleixner

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