Commit c9a1f766 authored Nov 19, 2024 by Alex Zenla Committed by Greg Kroah-Hartman Dec 05, 2024

9p/xen: fix init sequence



[ 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>

parent 3947b10e

net/9p/trans_xen.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -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: