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path: root/drivers/dma-buf/dma-buf.c
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Diffstat (limited to 'drivers/dma-buf/dma-buf.c')
-rw-r--r--drivers/dma-buf/dma-buf.c135
1 files changed, 135 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 68789e1..45f67a0 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);