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

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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: 7b07a2a7ca ("usb: gadget: functionfs: Add DMABUF import interface")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20240402110951.16376-3-paul@crapouillou.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paul Cercueil 2024-04-02 13:09:51 +02:00 committed by Greg Kroah-Hartman
parent 1500a7b279
commit 862b416560
1 changed files with 12 additions and 11 deletions
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23
drivers/usb/gadget/function/f_fs.c
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@ -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;
}