LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sebastian Siewior <bigeasy@linutronix.de>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>
Subject: [patch V3 32/32] cpuhotplug: Link lock stacks for hotplug callbacks
Date: Wed, 24 May 2017 10:15:43 +0200
Message-ID: <20170524081549.709375845@linutronix.de> (raw)
In-Reply-To: <20170524081511.203800767@linutronix.de>

[-- Attachment #0: cpuhotplug--Link-lock-stacks-for-hotplug-callbacks.patch --]
[-- Type: text/plain, Size: 2290 bytes --]

The CPU hotplug callbacks are not covered by lockdep versus the cpu hotplug
rwsem.

CPU0						CPU1
cpuhp_setup_state(STATE, startup, teardown);
 cpus_read_lock();
  invoke_callback_on_ap();
    kick_hotplug_thread(ap);
    wait_for_completion();			hotplug_thread_fn()
    						  lock(m);
						  do_stuff();
						  unlock(m);

Lockdep does not know about this dependency and will not trigger on the
following code sequence:

	  lock(m);
	  cpus_read_lock();
	  
Add a lockdep map and connect the initiators lock chain with the hotplug
thread lock chain, so potential deadlocks can be detected.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/cpu.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -66,6 +66,12 @@ struct cpuhp_cpu_state {
 
 static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
 
+#ifdef CONFIG_LOCKDEP
+static struct lock_class_key cpuhp_state_key;
+static struct lockdep_map cpuhp_state_lock_map =
+	STATIC_LOCKDEP_MAP_INIT("cpuhp_state", &cpuhp_state_key);
+#endif
+
 /**
  * cpuhp_step - Hotplug state machine step
  * @name:	Name of the step
@@ -403,6 +409,7 @@ static void cpuhp_thread_fun(unsigned in
 
 	st->should_run = false;
 
+	lock_map_acquire(&cpuhp_state_lock_map);
 	/* Single callback invocation for [un]install ? */
 	if (st->single) {
 		if (st->cb_state < CPUHP_AP_ONLINE) {
@@ -429,6 +436,7 @@ static void cpuhp_thread_fun(unsigned in
 		else if (st->state > st->target)
 			ret = cpuhp_ap_offline(cpu, st);
 	}
+	lock_map_release(&cpuhp_state_lock_map);
 	st->result = ret;
 	complete(&st->done);
 }
@@ -443,6 +451,9 @@ cpuhp_invoke_ap_callback(int cpu, enum c
 	if (!cpu_online(cpu))
 		return 0;
 
+	lock_map_acquire(&cpuhp_state_lock_map);
+	lock_map_release(&cpuhp_state_lock_map);
+
 	/*
 	 * If we are up and running, use the hotplug thread. For early calls
 	 * we invoke the thread function directly.
@@ -486,6 +497,8 @@ static int cpuhp_kick_ap_work(unsigned i
 	enum cpuhp_state state = st->state;
 
 	trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
+	lock_map_acquire(&cpuhp_state_lock_map);
+	lock_map_release(&cpuhp_state_lock_map);
 	__cpuhp_kick_ap_work(st);
 	wait_for_completion(&st->done);
 	trace_cpuhp_exit(cpu, st->state, state, st->result);

  parent reply index

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-24  8:15 [patch V3 00/32] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Thomas Gleixner
2017-05-24  8:15 ` [patch V3 01/32] cpu/hotplug: Provide cpus_read|write_[un]lock() Thomas Gleixner
2017-05-24 16:25   ` Paul E. McKenney
2017-05-26  8:31   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 02/32] cpu/hotplug: Provide lockdep_assert_cpus_held() Thomas Gleixner
2017-05-24 16:26   ` Paul E. McKenney
2017-05-26  8:32   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 03/32] cpu/hotplug: Provide cpuhp_setup/remove_state[_nocalls]_cpuslocked() Thomas Gleixner
2017-05-26  8:32   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 04/32] cpu/hotplug: Add __cpuhp_state_add_instance_cpuslocked() Thomas Gleixner
2017-05-26  8:33   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 05/32] stop_machine: Provide stop_machine_cpuslocked() Thomas Gleixner
2017-05-24 17:42   ` Paul E. McKenney
2017-05-26  8:33   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 06/32] padata: Make padata_alloc() static Thomas Gleixner
2017-05-26  8:34   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 07/32] padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() Thomas Gleixner
2017-05-26  8:35   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 08/32] x86/mtrr: Remove get_online_cpus() from mtrr_save_state() Thomas Gleixner
2017-05-26  8:35   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 09/32] cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner
2017-05-26  8:36   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 10/32] KVM/PPC/Book3S HV: " Thomas Gleixner
2017-05-26  8:36   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 11/32] hwtracing/coresight-etm3x: " Thomas Gleixner
2017-05-25 16:46   ` Mathieu Poirier
2017-05-26  8:37   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 12/32] hwtracing/coresight-etm4x: " Thomas Gleixner
2017-05-25 16:47   ` Mathieu Poirier
2017-05-26  8:37   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 13/32] perf/x86/intel/cqm: Use cpuhp_setup_state_cpuslocked() Thomas Gleixner
2017-05-26  8:38   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 14/32] ARM/hw_breakpoint: " Thomas Gleixner
2017-05-26  8:38   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 15/32] s390/kernel: Use stop_machine_cpuslocked() Thomas Gleixner
2017-05-24 10:57   ` Heiko Carstens
2017-05-26  8:39   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 16/32] powerpc/powernv: " Thomas Gleixner
2017-05-26  8:40   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 17/32] cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu() Thomas Gleixner
2017-05-26  8:40   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 18/32] x86/perf: Drop EXPORT of perf_check_microcode Thomas Gleixner
2017-05-26  8:41   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 19/32] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() Thomas Gleixner
2017-05-26  8:41   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 20/32] PCI: Use cpu_hotplug_disable() instead of get_online_cpus() Thomas Gleixner
2017-05-26  8:42   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 21/32] PCI: Replace the racy recursion prevention Thomas Gleixner
2017-05-26  8:42   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 22/32] ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() Thomas Gleixner
2017-05-26  8:43   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 23/32] perf/tracing/cpuhotplug: Fix locking order Thomas Gleixner
2017-05-24 18:30   ` Paul E. McKenney
2017-05-24 18:47     ` Thomas Gleixner
2017-05-24 21:10       ` Paul E. McKenney
2017-05-30 11:22     ` Peter Zijlstra
2017-05-30 16:25       ` Paul E. McKenney
2017-05-26  8:43   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 24/32] jump_label: Reorder hotplug lock and jump_label_lock Thomas Gleixner
2017-05-24 12:50   ` David Miller
2017-05-26  8:44   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 25/32] kprobes: Cure hotplug lock ordering issues Thomas Gleixner
2017-05-24 15:54   ` Masami Hiramatsu
2017-05-26  7:47     ` Thomas Gleixner
2017-05-26  8:45   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 26/32] arm64: Prevent cpu hotplug rwsem recursion Thomas Gleixner
2017-05-26  8:45   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 27/32] arm: Prevent " Thomas Gleixner
2017-05-26  8:46   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 28/32] s390: " Thomas Gleixner
2017-05-24 10:57   ` Heiko Carstens
2017-05-26  8:46   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 29/32] cpu/hotplug: Convert hotplug locking to percpu rwsem Thomas Gleixner
2017-05-26  8:47   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 30/32] sched: Provide is_percpu_thread() helper Thomas Gleixner
2017-05-26  8:47   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 31/32] acpi/processor: Prevent cpu hotplug deadlock Thomas Gleixner
2017-05-26  8:48   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` Thomas Gleixner [this message]
2017-05-26  8:48   ` [tip:smp/hotplug] cpuhotplug: Link lock stacks for hotplug callbacks tip-bot for Thomas Gleixner
2017-05-24 16:22 ` [patch V3 00/32] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Paul E. McKenney
2017-05-26  7:03 ` Ingo Molnar

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170524081549.709375845@linutronix.de \
    --to=tglx@linutronix.de \
    --cc=bigeasy@linutronix.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox