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drm: Rip out the racy, unused vblank signal code.
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Schedule a vblank signal, kill the process, and we'll go walking over freed
memory.  Given that no open-source userland exists using this, nor have I
ever heard of a consumer, just let this code die.

Signed-off-by: Eric Anholt <eric@anholt.net>
Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Dave Airlie <airlied@linux.ie>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Eric Anholt authored and Linus Torvalds committed Jan 28, 2009
1 parent 152a649 commit 30b2363
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Showing 3 changed files with 24 additions and 148 deletions.
161 changes: 23 additions & 138 deletions drivers/gpu/drm/drm_irq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,8 +106,6 @@ void drm_vblank_cleanup(struct drm_device *dev)

drm_free(dev->vbl_queue, sizeof(*dev->vbl_queue) * dev->num_crtcs,
DRM_MEM_DRIVER);
drm_free(dev->vbl_sigs, sizeof(*dev->vbl_sigs) * dev->num_crtcs,
DRM_MEM_DRIVER);
drm_free(dev->_vblank_count, sizeof(*dev->_vblank_count) *
dev->num_crtcs, DRM_MEM_DRIVER);
drm_free(dev->vblank_refcount, sizeof(*dev->vblank_refcount) *
Expand All @@ -132,19 +130,13 @@ int drm_vblank_init(struct drm_device *dev, int num_crtcs)
setup_timer(&dev->vblank_disable_timer, vblank_disable_fn,
(unsigned long)dev);
spin_lock_init(&dev->vbl_lock);
atomic_set(&dev->vbl_signal_pending, 0);
dev->num_crtcs = num_crtcs;

dev->vbl_queue = drm_alloc(sizeof(wait_queue_head_t) * num_crtcs,
DRM_MEM_DRIVER);
if (!dev->vbl_queue)
goto err;

dev->vbl_sigs = drm_alloc(sizeof(struct list_head) * num_crtcs,
DRM_MEM_DRIVER);
if (!dev->vbl_sigs)
goto err;

dev->_vblank_count = drm_alloc(sizeof(atomic_t) * num_crtcs,
DRM_MEM_DRIVER);
if (!dev->_vblank_count)
Expand Down Expand Up @@ -177,7 +169,6 @@ int drm_vblank_init(struct drm_device *dev, int num_crtcs)
/* Zero per-crtc vblank stuff */
for (i = 0; i < num_crtcs; i++) {
init_waitqueue_head(&dev->vbl_queue[i]);
INIT_LIST_HEAD(&dev->vbl_sigs[i]);
atomic_set(&dev->_vblank_count[i], 0);
atomic_set(&dev->vblank_refcount[i], 0);
}
Expand Down Expand Up @@ -540,15 +531,10 @@ int drm_modeset_ctl(struct drm_device *dev, void *data,
* \param data user argument, pointing to a drm_wait_vblank structure.
* \return zero on success or a negative number on failure.
*
* Verifies the IRQ is installed.
*
* If a signal is requested checks if this task has already scheduled the same signal
* for the same vblank sequence number - nothing to be done in
* that case. If the number of tasks waiting for the interrupt exceeds 100 the
* function fails. Otherwise adds a new entry to drm_device::vbl_sigs for this
* task.
*
* If a signal is not requested, then calls vblank_wait().
* This function enables the vblank interrupt on the pipe requested, then
* sleeps waiting for the requested sequence number to occur, and drops
* the vblank interrupt refcount afterwards. (vblank irq disable follows that
* after a timeout with no further vblank waits scheduled).
*/
int drm_wait_vblank(struct drm_device *dev, void *data,
struct drm_file *file_priv)
Expand All @@ -560,6 +546,9 @@ int drm_wait_vblank(struct drm_device *dev, void *data,
if ((!dev->pdev->irq) || (!dev->irq_enabled))
return -EINVAL;

if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
return -EINVAL;

if (vblwait->request.type &
~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK)) {
DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
Expand Down Expand Up @@ -597,136 +586,33 @@ int drm_wait_vblank(struct drm_device *dev, void *data,
vblwait->request.sequence = seq + 1;
}

if (flags & _DRM_VBLANK_SIGNAL) {
unsigned long irqflags;
struct list_head *vbl_sigs = &dev->vbl_sigs[crtc];
struct drm_vbl_sig *vbl_sig;

spin_lock_irqsave(&dev->vbl_lock, irqflags);

/* Check if this task has already scheduled the same signal
* for the same vblank sequence number; nothing to be done in
* that case
*/
list_for_each_entry(vbl_sig, vbl_sigs, head) {
if (vbl_sig->sequence == vblwait->request.sequence
&& vbl_sig->info.si_signo ==
vblwait->request.signal
&& vbl_sig->task == current) {
spin_unlock_irqrestore(&dev->vbl_lock,
irqflags);
vblwait->reply.sequence = seq;
goto done;
}
}

if (atomic_read(&dev->vbl_signal_pending) >= 100) {
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
ret = -EBUSY;
goto done;
}

spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

vbl_sig = drm_calloc(1, sizeof(struct drm_vbl_sig),
DRM_MEM_DRIVER);
if (!vbl_sig) {
ret = -ENOMEM;
goto done;
}

/* Get a refcount on the vblank, which will be released by
* drm_vbl_send_signals().
*/
ret = drm_vblank_get(dev, crtc);
if (ret) {
drm_free(vbl_sig, sizeof(struct drm_vbl_sig),
DRM_MEM_DRIVER);
goto done;
}

atomic_inc(&dev->vbl_signal_pending);

vbl_sig->sequence = vblwait->request.sequence;
vbl_sig->info.si_signo = vblwait->request.signal;
vbl_sig->task = current;
DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
vblwait->request.sequence, crtc);
dev->last_vblank_wait[crtc] = vblwait->request.sequence;
DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
(((drm_vblank_count(dev, crtc) -
vblwait->request.sequence) <= (1 << 23)) ||
!dev->irq_enabled));

spin_lock_irqsave(&dev->vbl_lock, irqflags);

list_add_tail(&vbl_sig->head, vbl_sigs);
if (ret != -EINTR) {
struct timeval now;

spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
do_gettimeofday(&now);

vblwait->reply.sequence = seq;
vblwait->reply.tval_sec = now.tv_sec;
vblwait->reply.tval_usec = now.tv_usec;
vblwait->reply.sequence = drm_vblank_count(dev, crtc);
DRM_DEBUG("returning %d to client\n",
vblwait->reply.sequence);
} else {
DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
vblwait->request.sequence, crtc);
dev->last_vblank_wait[crtc] = vblwait->request.sequence;
DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
(((drm_vblank_count(dev, crtc) -
vblwait->request.sequence) <= (1 << 23)) ||
!dev->irq_enabled));

if (ret != -EINTR) {
struct timeval now;

do_gettimeofday(&now);

vblwait->reply.tval_sec = now.tv_sec;
vblwait->reply.tval_usec = now.tv_usec;
vblwait->reply.sequence = drm_vblank_count(dev, crtc);
DRM_DEBUG("returning %d to client\n",
vblwait->reply.sequence);
} else {
DRM_DEBUG("vblank wait interrupted by signal\n");
}
DRM_DEBUG("vblank wait interrupted by signal\n");
}

done:
drm_vblank_put(dev, crtc);
return ret;
}

/**
* Send the VBLANK signals.
*
* \param dev DRM device.
* \param crtc CRTC where the vblank event occurred
*
* Sends a signal for each task in drm_device::vbl_sigs and empties the list.
*
* If a signal is not requested, then calls vblank_wait().
*/
static void drm_vbl_send_signals(struct drm_device *dev, int crtc)
{
struct drm_vbl_sig *vbl_sig, *tmp;
struct list_head *vbl_sigs;
unsigned int vbl_seq;
unsigned long flags;

spin_lock_irqsave(&dev->vbl_lock, flags);

vbl_sigs = &dev->vbl_sigs[crtc];
vbl_seq = drm_vblank_count(dev, crtc);

list_for_each_entry_safe(vbl_sig, tmp, vbl_sigs, head) {
if ((vbl_seq - vbl_sig->sequence) <= (1 << 23)) {
vbl_sig->info.si_code = vbl_seq;
send_sig_info(vbl_sig->info.si_signo,
&vbl_sig->info, vbl_sig->task);

list_del(&vbl_sig->head);

drm_free(vbl_sig, sizeof(*vbl_sig),
DRM_MEM_DRIVER);
atomic_dec(&dev->vbl_signal_pending);
drm_vblank_put(dev, crtc);
}
}

spin_unlock_irqrestore(&dev->vbl_lock, flags);
}

/**
* drm_handle_vblank - handle a vblank event
* @dev: DRM device
Expand All @@ -739,6 +625,5 @@ void drm_handle_vblank(struct drm_device *dev, int crtc)
{
atomic_inc(&dev->_vblank_count[crtc]);
DRM_WAKEUP(&dev->vbl_queue[crtc]);
drm_vbl_send_signals(dev, crtc);
}
EXPORT_SYMBOL(drm_handle_vblank);
2 changes: 1 addition & 1 deletion include/drm/drm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -458,7 +458,7 @@ enum drm_vblank_seq_type {
_DRM_VBLANK_FLIP = 0x8000000, /**< Scheduled buffer swap should flip */
_DRM_VBLANK_NEXTONMISS = 0x10000000, /**< If missed, wait for next vblank */
_DRM_VBLANK_SECONDARY = 0x20000000, /**< Secondary display controller */
_DRM_VBLANK_SIGNAL = 0x40000000 /**< Send signal instead of blocking */
_DRM_VBLANK_SIGNAL = 0x40000000 /**< Send signal instead of blocking, unsupported */
};

#define _DRM_VBLANK_TYPES_MASK (_DRM_VBLANK_ABSOLUTE | _DRM_VBLANK_RELATIVE)
Expand Down
9 changes: 0 additions & 9 deletions include/drm/drmP.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -545,13 +545,6 @@ struct drm_ctx_list {
struct drm_file *tag; /**< associated fd private data */
};

struct drm_vbl_sig {
struct list_head head;
unsigned int sequence;
struct siginfo info;
struct task_struct *task;
};

/* location of GART table */
#define DRM_ATI_GART_MAIN 1
#define DRM_ATI_GART_FB 2
Expand Down Expand Up @@ -903,8 +896,6 @@ struct drm_device {
wait_queue_head_t *vbl_queue; /**< VBLANK wait queue */
atomic_t *_vblank_count; /**< number of VBLANK interrupts (driver must alloc the right number of counters) */
spinlock_t vbl_lock;
struct list_head *vbl_sigs; /**< signal list to send on VBLANK */
atomic_t vbl_signal_pending; /* number of signals pending on all crtcs*/
atomic_t *vblank_refcount; /* number of users of vblank interruptsper crtc */
u32 *last_vblank; /* protected by dev->vbl_lock, used */
/* for wraparound handling */
Expand Down

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