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* [PATCH V1] fuse: Set fuse request error upon fuse abort connection
@ 2021-04-16 14:19 Pradeep P V K
  2021-05-10  7:52 ` pragalla
  2021-06-21  7:48 ` Miklos Szeredi
  0 siblings, 2 replies; 4+ messages in thread
From: Pradeep P V K @ 2021-04-16 14:19 UTC (permalink / raw)
  To: miklos; +Cc: stummala, linux-kernel, linux-fsdevel, Pradeep P V K

There is a minor race in setting the fuse out request error
between fuse_abort_conn() and fuse_dev_do_read() as explained
below.

Thread-1			  Thread-2
========			  ========
->fuse_simple_request()           ->shutdown
  ->__fuse_request_send()
    ->queue_request()		->fuse_abort_conn()
->fuse_dev_do_read()                ->acquire(fpq->lock)
  ->wait_for(fpq->lock) 	  ->set err to all req's in fpq->io
				  ->release(fpq->lock)
  ->acquire(fpq->lock)
  ->add req to fpq->io

The above scenario may cause Thread-1 request to add into
fpq->io list after Thread-2 sets -ECONNABORTED err to all
its requests in fpq->io list. This leaves Thread-1 request
with unset err and this further misleads as a completed
request without an err set upon request_end().

Handle this by setting the err appropriately.

Signed-off-by: Pradeep P V K <pragalla@codeaurora.org>
---
 fs/fuse/dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index a5ceccc..102c56f 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1283,6 +1283,7 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
 	clear_bit(FR_LOCKED, &req->flags);
 	if (!fpq->connected) {
 		err = fc->aborted ? -ECONNABORTED : -ENODEV;
+		req->out.h.error = err;
 		goto out_end;
 	}
 	if (err) {
-- 
2.7.4


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-06-21  7:48 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-04-16 14:19 [PATCH V1] fuse: Set fuse request error upon fuse abort connection Pradeep P V K
2021-05-10  7:52 ` pragalla
2021-05-10 14:05   ` Miklos Szeredi
2021-06-21  7:48 ` Miklos Szeredi

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