4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alex Zenla <alex@xxxxxxxxx>
[ Upstream commit 7ef3ae82a6ebbf4750967d1ce43bcdb7e44ff74b ]
Large amount of mount hangs observed during hotplugging of 9pfs devices. The
9pfs Xen driver attempts to initialize itself more than once, causing the
frontend and backend to disagree: the backend listens on a channel that the
frontend does not send on, resulting in stalled processing.
Only allow initialization of 9p frontend once.
Fixes: c15fe55d14b3b ("9p/xen: fix connection sequence")
Signed-off-by: Alex Zenla <alex@xxxxxxxxx>
Signed-off-by: Alexander Merritt <alexander@xxxxxxxxx>
Signed-off-by: Ariadne Conill <ariadne@ariadne.space>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Message-ID: <20241119211633.38321-1-alexander@xxxxxxxxx>
Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/9p/trans_xen.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index c87146a496363..77d7e6c3d7a27 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -480,6 +480,7 @@ static int xen_9pfs_front_init(struct xenbus_device *dev)
goto error;
}
+ xenbus_switch_state(dev, XenbusStateInitialised);
return 0;
error_xenbus:
@@ -527,8 +528,10 @@ static void xen_9pfs_front_changed(struct xenbus_device *dev,
break;
case XenbusStateInitWait:
- if (!xen_9pfs_front_init(dev))
- xenbus_switch_state(dev, XenbusStateInitialised);
+ if (dev->state != XenbusStateInitialising)
+ break;
+
+ xen_9pfs_front_init(dev);
break;
case XenbusStateConnected:
--
2.43.0
