4.19-stable review patch. If anyone has any objections, please let me know.
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From: Alex Zenla alex@edera.dev
[ 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@edera.dev Signed-off-by: Alexander Merritt alexander@edera.dev Signed-off-by: Ariadne Conill ariadne@ariadne.space Reviewed-by: Juergen Gross jgross@suse.com Message-ID: 20241119211633.38321-1-alexander@edera.dev Signed-off-by: Dominique Martinet asmadeus@codewreck.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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: