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

drivers/dma-buf/dma-buf.c

+108 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/dma-buf.h

+12 −0
Original line number Diff line number Diff line
@@ -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;

};



/**