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ledtrig-cpu: kill useless mutex to fix sleep in atomic context 

Seeing the following every time the CPU enters or leaves idle on a
Beagleboard:

BUG: sleeping function called from invalid context at kernel/mutex.c:269
in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0
no locks held by swapper/0/0.
[<c001659c>] (unwind_backtrace+0x0/0xf8) from [<c05aaa7c>] (mutex_lock_nested+0x24/0x380)
[<c05aaa7c>] (mutex_lock_nested+0x24/0x380) from [<c043bd1c>] (ledtrig_cpu+0x38/0x88)
[<c043bd1c>] (ledtrig_cpu+0x38/0x88) from [<c000f4b0>] (cpu_idle+0xf4/0x120)
[<c000f4b0>] (cpu_idle+0xf4/0x120) from [<c07e47c8>] (start_kernel+0x2bc/0x30c)

Miles Lane has reported seeing similar splats during system suspend.

The mutex in struct led_trigger_cpu appears to have no function: it
resides in a per-cpu data structure which never changes after the
trigger is registered.  So just remove it.

Reported-by: Miles Lane <miles.lane@gmail.com>
Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Bryan Wu <roc@roc-samos.(none)>
This commit is contained in:
Nathan Lynch 2012-11-05 06:20:31 -08:00 committed by Bryan Wu
parent 77b67063bb
commit 0b8728d6f1
1 changed files with 0 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/leds/ledtrig-cpu.c
View File

@ -33,8 +33,6 @@
struct led_trigger_cpu {
char name[MAX_NAME_LEN];
struct led_trigger *_trig;
struct mutex lock;
int lock_is_inited;
};
static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
@ -50,12 +48,6 @@ void ledtrig_cpu(enum cpu_led_event ledevt)
{
struct led_trigger_cpu *trig = &__get_cpu_var(cpu_trig);
/* mutex lock should be initialized before calling mutex_call() */
if (!trig->lock_is_inited)
return;
mutex_lock(&trig->lock);
/* Locate the correct CPU LED */
switch (ledevt) {
case CPU_LED_IDLE_END:
@ -75,8 +67,6 @@ void ledtrig_cpu(enum cpu_led_event ledevt)
/* Will leave the LED as it is */
break;
}
mutex_unlock(&trig->lock);
}
EXPORT_SYMBOL(ledtrig_cpu);
@ -117,14 +107,9 @@ static int __init ledtrig_cpu_init(void)
for_each_possible_cpu(cpu) {
struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
mutex_init(&trig->lock);
snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
mutex_lock(&trig->lock);
led_trigger_register_simple(trig->name, &trig->_trig);
trig->lock_is_inited = 1;
mutex_unlock(&trig->lock);
}
register_syscore_ops(&ledtrig_cpu_syscore_ops);
@ -142,15 +127,9 @@ static void __exit ledtrig_cpu_exit(void)
for_each_possible_cpu(cpu) {
struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
mutex_lock(&trig->lock);
led_trigger_unregister_simple(trig->_trig);
trig->_trig = NULL;
memset(trig->name, 0, MAX_NAME_LEN);
trig->lock_is_inited = 0;
mutex_unlock(&trig->lock);
mutex_destroy(&trig->lock);
}
unregister_syscore_ops(&ledtrig_cpu_syscore_ops);