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| author | Paul Parsons <lost.distance@yahoo.com> | 2011-05-13 02:46:03 +0100 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2011-05-23 12:50:43 +0200 |
| commit | fda5fe19725edd6805f2fd742235d1a0d0ba93f5 (patch) | |
| tree | 86c5e5e7fe1b41ecf18233149f6a1f7a60b4cd45 /drivers/char | |
| parent | 81024fc41a9353160bc445fda4f96d1aa5e82791 (diff) | |
| download | linux-fda5fe19725edd6805f2fd742235d1a0d0ba93f5.tar.gz linux-fda5fe19725edd6805f2fd742235d1a0d0ba93f5.tar.bz2 linux-fda5fe19725edd6805f2fd742235d1a0d0ba93f5.zip | |
apm-emulation: apm_mutex breaks ACK; remove it
apm_mutex is locked by a process (e.g. apm -s) at the start of apm_ioctl() and
remains locked while pm_suspend() is called. Any subsequent process trying to
ACK the suspend (e.g. apmd) is then blocked at the start of apm_ioctl(),
causing the suspend to be delayed for 5 seconds in apm_suspend_notifier()
while the ACK times out. In short, ACKs don't work.
The driver's data structures are sufficiently protected by assorted locks. And
pm_suspend() has its own mutex to prevent reentrancy. Consequently there is no
obvious requirement for apm_mutex, which evolved from earlier BKL calls. So
let's remove it.
Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/apm-emulation.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c index 45b987c9889e..548708c4b2b8 100644 --- a/drivers/char/apm-emulation.c +++ b/drivers/char/apm-emulation.c @@ -126,7 +126,6 @@ struct apm_user { /* * Local variables */ -static DEFINE_MUTEX(apm_mutex); static atomic_t suspend_acks_pending = ATOMIC_INIT(0); static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0); static int apm_disabled; @@ -275,7 +274,6 @@ apm_ioctl(struct file *filp, u_int cmd, u_long arg) if (!as->suser || !as->writer) return -EPERM; - mutex_lock(&apm_mutex); switch (cmd) { case APM_IOC_SUSPEND: mutex_lock(&state_lock); @@ -336,7 +334,6 @@ apm_ioctl(struct file *filp, u_int cmd, u_long arg) mutex_unlock(&state_lock); break; } - mutex_unlock(&apm_mutex); return err; } @@ -371,7 +368,6 @@ static int apm_open(struct inode * inode, struct file * filp) { struct apm_user *as; - mutex_lock(&apm_mutex); as = kzalloc(sizeof(*as), GFP_KERNEL); if (as) { /* @@ -391,7 +387,6 @@ static int apm_open(struct inode * inode, struct file * filp) filp->private_data = as; } - mutex_unlock(&apm_mutex); return as ? 0 : -ENOMEM; } |