drm: Rip out the racy, unused vblank signal code.

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>

1 files changed, 23 insertions, 138 deletions

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 477caa1b1e4b..69aa0ab28403 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -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) *
@@ -132,7 +130,6 @@ 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,
@@ -140,11 +137,6 @@ int drm_vblank_init(struct drm_device *dev, int num_crtcs)
         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)
@@ -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);
         }
@@ -540,15 +531,10 @@ out:
  * \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)
@@ -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",
@@ -597,89 +586,26 @@ 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:
@@ -688,46 +614,6 @@ done:
 }
 
 /**
- * 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
  * @crtc: where this event occurred
@@ -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);