diff options
| -rw-r--r-- | drivers/dma-buf/dma-buf.c | 135 | ||||
| -rw-r--r-- | include/linux/dma-buf.h | 12 |
2 files changed, 147 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 68789e1db97..45f67a0e667 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -30,6 +30,7 @@ #include <linux/export.h> #include <linux/debugfs.h> #include <linux/seq_file.h> +#include <linux/poll.h> #include <linux/reservation.h> static inline int is_dma_buf_file(struct file *); @@ -52,6 +53,16 @@ static int dma_buf_release(struct inode *inode, struct file *file) BUG_ON(dmabuf->vmapping_counter); + /* + * Any fences that a dma-buf poll can wait on should be signaled + * before releasing dma-buf. This is the responsibility of each + * driver that uses the reservation objects. + * + * If you hit this BUG() it means someone dropped their ref to the + * dma-buf while still having pending operation to the buffer. + */ + BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active); + dmabuf->ops->release(dmabuf); mutex_lock(&db_list.lock); @@ -82,9 +93,129 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) return dmabuf->ops->mmap(dmabuf, vma); } +static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) +{ + struct dma_buf *dmabuf; + loff_t base; + + if (!is_dma_buf_file(file)) + return -EBADF; + + dmabuf = file->private_data; + + /* only support discovering the end of the buffer, + but also allow SEEK_SET to maintain the idiomatic + SEEK_END(0), SEEK_CUR(0) pattern */ + if (whence == SEEK_END) + base = dmabuf->size; + else if (whence == SEEK_SET) + base = 0; + else + return -EINVAL; + + if (offset != 0) + return -EINVAL; + + return base + offset; +} + +static void dma_buf_poll_cb(struct fence *fence, struct fence_cb *cb) +{ + struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb; + unsigned long flags; + + spin_lock_irqsave(&dcb->poll->lock, flags); + wake_up_locked_poll(dcb->poll, dcb->active); + dcb->active = 0; + spin_unlock_irqrestore(&dcb->poll->lock, flags); +} + +static unsigned int dma_buf_poll(struct file *file, poll_table *poll) +{ + struct dma_buf *dmabuf; + struct reservation_object *resv; + unsigned long events; + + dmabuf = file->private_data; + if (!dmabuf || !dmabuf->resv) + return POLLERR; + + resv = dmabuf->resv; + + poll_wait(file, &dmabuf->poll, poll); + + events = poll_requested_events(poll) & (POLLIN | POLLOUT); + if (!events) + return 0; + + ww_mutex_lock(&resv->lock, NULL); + + if (resv->fence_excl && (!(events & POLLOUT) || + resv->fence_shared_count == 0)) { + struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl; + unsigned long pevents = POLLIN; + + if (resv->fence_shared_count == 0) + pevents |= POLLOUT; + + spin_lock_irq(&dmabuf->poll.lock); + if (dcb->active) { + dcb->active |= pevents; + events &= ~pevents; + } else + dcb->active = pevents; + spin_unlock_irq(&dmabuf->poll.lock); + + if (events & pevents) { + if (!fence_add_callback(resv->fence_excl, + &dcb->cb, dma_buf_poll_cb)) + events &= ~pevents; + else + /* + * No callback queued, wake up any additional + * waiters. + */ + dma_buf_poll_cb(NULL, &dcb->cb); + } + } + + if ((events & POLLOUT) && resv->fence_shared_count > 0) { + struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared; + int i; + + /* Only queue a new callback if no event has fired yet */ + spin_lock_irq(&dmabuf->poll.lock); + if (dcb->active) + events &= ~POLLOUT; + else + dcb->active = POLLOUT; + spin_unlock_irq(&dmabuf->poll.lock); + + if (!(events & POLLOUT)) + goto out; + + for (i = 0; i < resv->fence_shared_count; ++i) + if (!fence_add_callback(resv->fence_shared[i], + &dcb->cb, dma_buf_poll_cb)) { + events &= ~POLLOUT; + break; + } + + /* No callback queued, wake up any additional waiters. */ + if (i == resv->fence_shared_count) + dma_buf_poll_cb(NULL, &dcb->cb); + } + +out: + ww_mutex_unlock(&resv->lock); + return events; +} + static const struct file_operations dma_buf_fops = { .release = dma_buf_release, .mmap = dma_buf_mmap_internal, + .llseek = dma_buf_llseek, + .poll = dma_buf_poll, }; /* @@ -144,6 +275,10 @@ struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops, dmabuf->ops = ops; dmabuf->size = size; dmabuf->exp_name = exp_name; + init_waitqueue_head(&dmabuf->poll); + dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll; + dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0; + if (!resv) { resv = (struct reservation_object *)&dmabuf[1]; reservation_object_init(resv); diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index fd7def2e0ae..694e1fe1c4b 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -30,6 +30,8 @@ #include <linux/list.h> #include <linux/dma-mapping.h> #include <linux/fs.h> +#include <linux/fence.h> +#include <linux/wait.h> struct device; struct dma_buf; @@ -130,6 +132,16 @@ struct dma_buf { struct list_head list_node; void *priv; struct reservation_object *resv; + + /* poll support */ + wait_queue_head_t poll; + + struct dma_buf_poll_cb_t { + struct fence_cb cb; + wait_queue_head_t *poll; + + unsigned long active; + } cb_excl, cb_shared; }; /** |