Commit 9b495a58 authored by Maarten Lankhorst's avatar Maarten Lankhorst Committed by Greg Kroah-Hartman

dma-buf: add poll support, v3

Thanks to Fengguang Wu for spotting a missing static cast.

v2:
- Kill unused variable need_shared.
v3:
- Clarify the BUG() in dma_buf_release some more. (Rob Clark)
Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: default avatarSumit Semwal <sumit.semwal@linaro.org>
Acked-by: default avatarDaniel Vetter <daniel@ffwll.ch>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0ba6b8fb
......@@ -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);
......@@ -108,10 +119,103 @@ static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
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,
};
/*
......@@ -171,6 +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);
......
......@@ -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;
};
/**
......
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