Reorganize the fence wait loop somewhat to make it look more like the examples in set_current_state() kerneldoc, and add some code comments.
Also if we're about to time out, make sure we check again whether the fence is actually signaled.
Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Brian Paul brianp@vmware.com Reviewed-by: Deepak Rawat drawat@vmware.com --- drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 38 ++++++++++++++++++--------- 1 file changed, 26 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c index 9ed544f8958f..ea41d74d8341 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c @@ -175,7 +175,6 @@ static long vmw_fence_wait(struct dma_fence *f, bool intr, signed long timeout) struct vmw_private *dev_priv = fman->dev_priv; struct vmwgfx_wait_cb cb; long ret = timeout; - unsigned long irq_flags;
if (likely(vmw_fence_obj_signaled(fence))) return timeout; @@ -183,7 +182,7 @@ static long vmw_fence_wait(struct dma_fence *f, bool intr, signed long timeout) vmw_fifo_ping_host(dev_priv, SVGA_SYNC_GENERIC); vmw_seqno_waiter_add(dev_priv);
- spin_lock_irqsave(f->lock, irq_flags); + spin_lock(f->lock);
if (intr && signal_pending(current)) { ret = -ERESTARTSYS; @@ -194,30 +193,45 @@ static long vmw_fence_wait(struct dma_fence *f, bool intr, signed long timeout) cb.task = current; list_add(&cb.base.node, &f->cb_list);
- while (ret > 0) { + for (;;) { __vmw_fences_update(fman); - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &f->flags)) - break;
+ /* + * We can use the barrier free __set_current_state() since + * DMA_FENCE_FLAG_SIGNALED_BIT + wakeup is protected by the + * fence spinlock. + */ if (intr) __set_current_state(TASK_INTERRUPTIBLE); else __set_current_state(TASK_UNINTERRUPTIBLE); - spin_unlock_irqrestore(f->lock, irq_flags);
- ret = schedule_timeout(ret); + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &f->flags)) { + if (ret == 0 && timeout > 0) + ret = 1; + break; + }
- spin_lock_irqsave(f->lock, irq_flags); - if (ret > 0 && intr && signal_pending(current)) + if (intr && signal_pending(current)) { ret = -ERESTARTSYS; - } + break; + }
+ if (ret == 0) + break; + + spin_unlock(f->lock); + + ret = schedule_timeout(ret); + + spin_lock(f->lock); + } + __set_current_state(TASK_RUNNING); if (!list_empty(&cb.base.node)) list_del(&cb.base.node); - __set_current_state(TASK_RUNNING);
out: - spin_unlock_irqrestore(f->lock, irq_flags); + spin_unlock(f->lock);
vmw_seqno_waiter_remove(dev_priv);