diff options
| author | Dave Airlie <airlied@starflyer.(none)> | 2005-11-24 21:41:14 +1100 |
|---|---|---|
| committer | Dave Airlie <airlied@linux.ie> | 2005-11-24 21:41:14 +1100 |
| commit | cf65f1623dd005ddfb1cbba20af3423a6c638dbe (patch) | |
| tree | aa1a69092764317ff9ac49c25be5e423882b90d6 /drivers/char | |
| parent | 33bc227e4e48ddadcf2eacb381c19df338f0a6c8 (diff) | |
drm: fix quiescent locking
A fix for a locking bug which is triggered when a client tries to lock with
flag DMA_QUIESCENT (typically the X server), but gets interrupted by a signal.
The locking IOCTL should then return an error, but if DMA_QUIESCENT succeeds
it returns 0, and the client falsely thinks it has the lock. In addition
The client waits for DMA_QUISCENT and possibly DMA_READY without having the lock.
From: Thomas Hellstrom
Signed-off-by: Dave Airlie <airlied@linux.ie>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/drm/drm_lock.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/char/drm/drm_lock.c b/drivers/char/drm/drm_lock.c index b276ae8a663..b48a595d54e 100644 --- a/drivers/char/drm/drm_lock.c +++ b/drivers/char/drm/drm_lock.c @@ -104,6 +104,10 @@ int drm_lock(struct inode *inode, struct file *filp, __set_current_state(TASK_RUNNING); remove_wait_queue(&dev->lock.lock_queue, &entry); + DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock"); + if (ret) + return ret; + sigemptyset(&dev->sigmask); sigaddset(&dev->sigmask, SIGSTOP); sigaddset(&dev->sigmask, SIGTSTP); @@ -116,8 +120,12 @@ int drm_lock(struct inode *inode, struct file *filp, if (dev->driver->dma_ready && (lock.flags & _DRM_LOCK_READY)) dev->driver->dma_ready(dev); - if (dev->driver->dma_quiescent && (lock.flags & _DRM_LOCK_QUIESCENT)) - return dev->driver->dma_quiescent(dev); + if (dev->driver->dma_quiescent && (lock.flags & _DRM_LOCK_QUIESCENT)) { + if (dev->driver->dma_quiescent(dev)) { + DRM_DEBUG("%d waiting for DMA quiescent\n", lock.context); + return DRM_ERR(EBUSY); + } + } /* dev->driver->kernel_context_switch isn't used by any of the x86 * drivers but is used by the Sparc driver. @@ -128,9 +136,7 @@ int drm_lock(struct inode *inode, struct file *filp, dev->driver->kernel_context_switch(dev, dev->last_context, lock.context); } - DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock"); - - return ret; + return 0; } /** |