* [PATCH] cpu/hotplug: drop the device lock on error
@ 2017-06-02 14:27 Sebastian Andrzej Siewior
2017-06-03 7:39 ` [tip:smp/urgent] cpu/hotplug: Drop " tip-bot for Sebastian Andrzej Siewior
0 siblings, 1 reply; 2+ messages in thread
From: Sebastian Andrzej Siewior @ 2017-06-02 14:27 UTC (permalink / raw)
To: Thomas Gleixner; +Cc: Ingo Molnar, linux-kernel
If a custom CPU target is specified and that one is not available _or_
can't be interrupted then leave to userland without dropping a lock as
notice by lockdep:
|echo 133 > /sys/devices/system/cpu/cpu7/hotplug/target
| ================================================
| [ BUG: lock held when returning to user space! ]
| ------------------------------------------------
| bash/503 is leaving the kernel with locks still held!
| 1 lock held by bash/503:
| #0: (device_hotplug_lock){+.+...}, at: [<ffffffff815b5650>] lock_device_hotplug_sysfs+0x10/0x40
So release the lock then.
Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable")
Cc: stable@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/cpu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 7435ffc6163b..912621eb2286 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1627,13 +1627,13 @@ static ssize_t write_cpuhp_target(struct device *dev,
ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
mutex_unlock(&cpuhp_state_mutex);
if (ret)
- return ret;
+ goto out;
if (st->state < target)
ret = do_cpu_up(dev->id, target);
else
ret = do_cpu_down(dev->id, target);
-
+out:
unlock_device_hotplug();
return ret ? ret : count;
}
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:smp/urgent] cpu/hotplug: Drop the device lock on error
2017-06-02 14:27 [PATCH] cpu/hotplug: drop the device lock on error Sebastian Andrzej Siewior
@ 2017-06-03 7:39 ` tip-bot for Sebastian Andrzej Siewior
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Sebastian Andrzej Siewior @ 2017-06-03 7:39 UTC (permalink / raw)
To: linux-tip-commits; +Cc: mingo, hpa, linux-kernel, tglx, bigeasy
Commit-ID: 40da1b11f01e43aad1aa6cea64681b6125e8a2a7
Gitweb: http://git.kernel.org/tip/40da1b11f01e43aad1aa6cea64681b6125e8a2a7
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Fri, 2 Jun 2017 16:27:14 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 3 Jun 2017 09:35:04 +0200
cpu/hotplug: Drop the device lock on error
If a custom CPU target is specified and that one is not available _or_
can't be interrupted then the code returns to userland without dropping a
lock as notices by lockdep:
|echo 133 > /sys/devices/system/cpu/cpu7/hotplug/target
| ================================================
| [ BUG: lock held when returning to user space! ]
| ------------------------------------------------
| bash/503 is leaving the kernel with locks still held!
| 1 lock held by bash/503:
| #0: (device_hotplug_lock){+.+...}, at: [<ffffffff815b5650>] lock_device_hotplug_sysfs+0x10/0x40
So release the lock then.
Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170602142714.3ogo25f2wbq6fjpj@linutronix.de
---
kernel/cpu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 9ae6fbe..cb51034 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1658,13 +1658,13 @@ static ssize_t write_cpuhp_target(struct device *dev,
ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
mutex_unlock(&cpuhp_state_mutex);
if (ret)
- return ret;
+ goto out;
if (st->state < target)
ret = do_cpu_up(dev->id, target);
else
ret = do_cpu_down(dev->id, target);
-
+out:
unlock_device_hotplug();
return ret ? ret : count;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
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