Commit-ID: b7a349819d4b9b5db64e523351e66a79a758eaa5 Gitweb: http://git.kernel.org/tip/b7a349819d4b9b5db64e523351e66a79a758eaa5 Author: Thomas Gleixner <[email protected]> AuthorDate: Tue, 12 Sep 2017 21:37:00 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 14 Sep 2017 11:41:04 +0200
watchdog/core: Rework CPU hotplug locking The watchdog proc interface causes extensive recursive locking of the CPU hotplug percpu rwsem, which is deadlock prone. Replace the get/put_online_cpus() pairs with cpu_hotplug_disable()/enable() calls for now. Later patches will remove that requirement completely. Reported-by: Borislav Petkov <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Don Zickus <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Nicholas Piggin <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sebastian Siewior <[email protected]> Cc: Ulrich Obergfell <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/watchdog.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index b2d4675..cd79f64 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -703,7 +703,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write, int err, old, new; int *watchdog_param = (int *)table->data; - get_online_cpus(); + cpu_hotplug_disable(); mutex_lock(&watchdog_proc_mutex); /* @@ -752,7 +752,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write, } out: mutex_unlock(&watchdog_proc_mutex); - put_online_cpus(); + cpu_hotplug_enable(); return err; } @@ -794,7 +794,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write, { int err, old, new; - get_online_cpus(); + cpu_hotplug_disable(); mutex_lock(&watchdog_proc_mutex); old = ACCESS_ONCE(watchdog_thresh); @@ -818,7 +818,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write, } out: mutex_unlock(&watchdog_proc_mutex); - put_online_cpus(); + cpu_hotplug_enable(); return err; } @@ -833,7 +833,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write, { int err; - get_online_cpus(); + cpu_hotplug_disable(); mutex_lock(&watchdog_proc_mutex); err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); @@ -856,7 +856,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write, } mutex_unlock(&watchdog_proc_mutex); - put_online_cpus(); + cpu_hotplug_enable(); return err; }
