From: Nikolaus Rath <Nikolaus@rath.org>
Date: Tue, 4 Oct 2016 03:23:42 +0000 (-0700)
Subject: fuse_lowlevel_notify_poll(): use master channel
X-Git-Tag: fuse-3.0.0rc1~94
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e572cfbd3490add057b867c29d37da51ee8217e5;p=qemu-gpiodev%2Flibfuse.git

fuse_lowlevel_notify_poll(): use master channel

In theory, a poll handle could hang around much longer than the worker
thread that creates it. Furthermore, the thread that created the
pollhandle is no more likely to call fuse_lowlevel_notify_poll() than
any other thread.

In theory, this would have kept the channel alive for much longer than
necessary. In practice, there seems to have been a bug that prevented
this - and instead allowed the channel to be destroyed while there
was still a pollhandle referring to it.

Instead of fixing this by calling fuse_chan_get() and fuse_chan_put() in
do_poll() and fuse_pollhandle_destroy(), we simply transmit poll
notifications over the master channel now.
---

diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 82cbe06..d7b1fd1 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -44,8 +44,7 @@
 
 struct fuse_pollhandle {
 	uint64_t kh;
-	struct fuse_chan *ch;
-	struct fuse_ll *f;
+	struct fuse_session *se;
 };
 
 static size_t pagesize;
@@ -1794,8 +1793,7 @@ static void do_poll(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 				return;
 			}
 			ph->kh = arg->kh;
-			ph->ch = req->ch;
-			ph->f = req->f;
+			ph->se = req->se;
 		}
 
 		req->f->op.poll(req, nodeid, &fi, ph);
@@ -2110,7 +2108,8 @@ int fuse_lowlevel_notify_poll(struct fuse_pollhandle *ph)
 		iov[1].iov_base = &outarg;
 		iov[1].iov_len = sizeof(outarg);
 
-		return send_notify_iov(ph->f, ph->ch, FUSE_NOTIFY_POLL, iov, 2);
+		return send_notify_iov(ph->se->f, ph->se->ch,
+				       FUSE_NOTIFY_POLL, iov, 2);
 	} else {
 		return 0;
 	}