freebsd-dev/sys/dev/drm/drm_lock.c
Robert Noland 6f81ba0e97 Don't return EINVAL when trying to unlock.
anholt thinks that he added this check as part of some regression testing,
but it is failing at least some of the time.  I don't want to remove it
just yet.  I added a bit of debugging to help identify the issue.

Approved by:	kib
2008-08-30 01:00:18 +00:00

210 lines
6.1 KiB
C

/*-
* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Authors:
* Rickard E. (Rik) Faith <faith@valinux.com>
* Gareth Hughes <gareth@valinux.com>
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/** @file drm_lock.c
* Implementation of the ioctls and other support code for dealing with the
* hardware lock.
*
* The DRM hardware lock is a shared structure between the kernel and userland.
*
* On uncontended access where the new context was the last context, the
* client may take the lock without dropping down into the kernel, using atomic
* compare-and-set.
*
* If the client finds during compare-and-set that it was not the last owner
* of the lock, it calls the DRM lock ioctl, which may sleep waiting for the
* lock, and may have side-effects of kernel-managed context switching.
*
* When the client releases the lock, if the lock is marked as being contended
* by another client, then the DRM unlock ioctl is called so that the
* contending client may be woken up.
*/
#include "dev/drm/drmP.h"
int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
{
unsigned int old, new;
do {
old = *lock;
if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
else new = context | _DRM_LOCK_HELD;
} while (!atomic_cmpset_int(lock, old, new));
if (_DRM_LOCKING_CONTEXT(old) == context) {
if (old & _DRM_LOCK_HELD) {
if (context != DRM_KERNEL_CONTEXT) {
DRM_ERROR("%d holds heavyweight lock\n",
context);
}
return 0;
}
}
if (new == (context | _DRM_LOCK_HELD)) {
/* Have lock */
return 1;
}
return 0;
}
/* This takes a lock forcibly and hands it to context. Should ONLY be used
inside *_unlock to give lock to kernel before calling *_dma_schedule. */
int drm_lock_transfer(struct drm_device *dev,
__volatile__ unsigned int *lock, unsigned int context)
{
unsigned int old, new;
dev->lock.file_priv = NULL;
do {
old = *lock;
new = context | _DRM_LOCK_HELD;
} while (!atomic_cmpset_int(lock, old, new));
return 1;
}
int drm_lock_free(struct drm_device *dev,
__volatile__ unsigned int *lock, unsigned int context)
{
unsigned int old, new;
dev->lock.file_priv = NULL;
do {
old = *lock;
new = 0;
} while (!atomic_cmpset_int(lock, old, new));
if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
DRM_ERROR("%d freed heavyweight lock held by %d\n",
context, _DRM_LOCKING_CONTEXT(old));
return 1;
}
DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
return 0;
}
int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
drm_lock_t *lock = data;
int ret = 0;
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
DRM_CURRENTPID, lock->context);
return EINVAL;
}
DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
lock->flags);
if (dev->driver.use_dma_queue && lock->context < 0)
return EINVAL;
DRM_LOCK();
for (;;) {
if (drm_lock_take(&dev->lock.hw_lock->lock, lock->context)) {
dev->lock.file_priv = file_priv;
dev->lock.lock_time = jiffies;
atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
break; /* Got lock */
}
/* Contention */
#if defined(__FreeBSD__) && __FreeBSD_version > 500000
ret = mtx_sleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
PZERO | PCATCH, "drmlk2", 0);
#else
ret = tsleep((void *)&dev->lock.lock_queue, PZERO | PCATCH,
"drmlk2", 0);
#endif
if (ret != 0)
break;
}
DRM_UNLOCK();
DRM_DEBUG("%d %s\n", lock->context, ret ? "interrupted" : "has lock");
if (ret != 0)
return ret;
/* XXX: Add signal blocking here */
if (dev->driver.dma_quiescent != NULL &&
(lock->flags & _DRM_LOCK_QUIESCENT))
dev->driver.dma_quiescent(dev);
return 0;
}
int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
drm_lock_t *lock = data;
DRM_DEBUG("%d (pid %d) requests unlock (0x%08x), flags = 0x%08x\n",
lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
lock->flags);
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
DRM_CURRENTPID, lock->context);
return EINVAL;
}
#if 0
/* Check that the context unlock being requested actually matches
* who currently holds the lock.
*/
if (!_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) ||
_DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock) != lock->context)
return EINVAL;
#endif
DRM_SPINLOCK(&dev->tsk_lock);
if (dev->locked_task_call != NULL) {
dev->locked_task_call(dev);
dev->locked_task_call = NULL;
}
DRM_SPINUNLOCK(&dev->tsk_lock);
atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
DRM_LOCK();
drm_lock_transfer(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT);
if (drm_lock_free(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT)) {
DRM_ERROR("\n");
}
DRM_UNLOCK();
return 0;
}