Commit 862b4165 authored by Paul Cercueil's avatar Paul Cercueil Committed by Greg Kroah-Hartman
Browse files

usb: gadget: functionfs: Wait for fences before enqueueing DMABUF 



Instead of bailing when fences have already been installed on the
DMABUF, wait for them (with a timeout) when doing a blocking operation.

This fixes the issue where userspace would submit a DMABUF with fences
already installed, with the (correct) expectation that it would just
work.

Fixes: 7b07a2a7 ("usb: gadget: functionfs: Add DMABUF import interface")
Signed-off-by: default avatarPaul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20240402110951.16376-3-paul@crapouillou.net


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1500a7b2

drivers/usb/gadget/function/f_fs.c

+12 −11
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ 


#define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */



#define DMABUF_ENQUEUE_TIMEOUT_MS 5000



MODULE_IMPORT_NS(DMA_BUF);



/* Reference counter handling */
@@ -1580,9 +1582,11 @@ static int ffs_dmabuf_transfer(struct file *file, 
	struct usb_request *usb_req;

	enum dma_resv_usage resv_dir;

	struct dma_buf *dmabuf;

	unsigned long timeout;

	struct ffs_ep *ep;

	bool cookie;

	u32 seqno;

	long retl;

	int ret;



	if (req->flags & ~USB_FFS_DMABUF_TRANSFER_MASK)
@@ -1616,17 +1620,14 @@ static int ffs_dmabuf_transfer(struct file *file, 
		goto err_attachment_put;



	/* Make sure we don't have writers */

	if (!dma_resv_test_signaled(dmabuf->resv, DMA_RESV_USAGE_WRITE)) {

		pr_vdebug("FFS WRITE fence is not signaled\n");

		ret = -EBUSY;

		goto err_resv_unlock;

	}



	/* If we're writing to the DMABUF, make sure we don't have readers */

	if (epfile->in &&

	    !dma_resv_test_signaled(dmabuf->resv, DMA_RESV_USAGE_READ)) {

		pr_vdebug("FFS READ fence is not signaled\n");

		ret = -EBUSY;

	timeout = nonblock ? 0 : msecs_to_jiffies(DMABUF_ENQUEUE_TIMEOUT_MS);

	retl = dma_resv_wait_timeout(dmabuf->resv,

				     dma_resv_usage_rw(epfile->in),

				     true, timeout);

	if (retl == 0)

		retl = -EBUSY;

	if (retl < 0) {

		ret = (int)retl;

		goto err_resv_unlock;

	}