From: Alex Zenla <alex@edera.dev>
Date: Tue, 19 Nov 2024 21:16:33 +0000 (+0000)
Subject: 9p/xen: fix init sequence
X-Git-Tag: v5.15.174~200
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db94e06c24cd4f3e4f6605d5756027fb95be179d;p=thirdparty%2Fkernel%2Fstable.git

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>
---

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 99e6b2483311c..716736046a18f 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -487,6 +487,7 @@ static int xen_9pfs_front_init(struct xenbus_device *dev)
 		goto error;
 	}
 
+	xenbus_switch_state(dev, XenbusStateInitialised);
 	return 0;
 
  error_xenbus:
@@ -534,8 +535,10 @@ 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: