From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Michael Brown <mbrown@fensystems.co.uk>,
Paul Durrant <paul@xen.org>,
"David S. Miller" <davem@davemloft.net>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 33/37] xen-netback: Check for hotplug-status existence before watching
Date: Mon, 26 Apr 2021 09:29:34 +0200 [thread overview]
Message-ID: <20210426072818.365616663@linuxfoundation.org> (raw)
In-Reply-To: <20210426072817.245304364@linuxfoundation.org>
From: Michael Brown <mbrown@fensystems.co.uk>
[ Upstream commit 2afeec08ab5c86ae21952151f726bfe184f6b23d ]
The logic in connect() is currently written with the assumption that
xenbus_watch_pathfmt() will return an error for a node that does not
exist. This assumption is incorrect: xenstore does allow a watch to
be registered for a nonexistent node (and will send notifications
should the node be subsequently created).
As of commit 1f2565780 ("xen-netback: remove 'hotplug-status' once it
has served its purpose"), this leads to a failure when a domU
transitions into XenbusStateConnected more than once. On the first
domU transition into Connected state, the "hotplug-status" node will
be deleted by the hotplug_status_changed() callback in dom0. On the
second or subsequent domU transition into Connected state, the
hotplug_status_changed() callback will therefore never be invoked, and
so the backend will remain stuck in InitWait.
This failure prevents scenarios such as reloading the xen-netfront
module within a domU, or booting a domU via iPXE. There is
unfortunately no way for the domU to work around this dom0 bug.
Fix by explicitly checking for existence of the "hotplug-status" node,
thereby creating the behaviour that was previously assumed to exist.
Signed-off-by: Michael Brown <mbrown@fensystems.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/xen-netback/xenbus.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 78788402edd8..e6646c8a7bdb 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -1040,11 +1040,15 @@ static void connect(struct backend_info *be)
xenvif_carrier_on(be->vif);
unregister_hotplug_status_watch(be);
- err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch, NULL,
- hotplug_status_changed,
- "%s/%s", dev->nodename, "hotplug-status");
- if (!err)
+ if (xenbus_exists(XBT_NIL, dev->nodename, "hotplug-status")) {
+ err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
+ NULL, hotplug_status_changed,
+ "%s/%s", dev->nodename,
+ "hotplug-status");
+ if (err)
+ goto err;
be->have_hotplug_status_watch = 1;
+ }
netif_tx_wake_all_queues(be->vif->dev);
--
2.30.2
next prev parent reply other threads:[~2021-04-26 7:37 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-26 7:29 [PATCH 4.9 00/37] 4.9.268-rc1 review Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 01/37] net/sctp: fix race condition in sctp_destroy_sock Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 02/37] Input: nspire-keypad - enable interrupts only when opened Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 03/37] dmaengine: dw: Make it dependent to HAS_IOMEM Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 04/37] ARM: dts: Fix moving mmc devices with aliases for omap4 & 5 Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 05/37] arc: kernel: Return -EFAULT if copy_to_user() fails Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 06/37] neighbour: Disregard DEAD dst in neigh_update Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 07/37] ARM: keystone: fix integer overflow warning Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 08/37] ASoC: fsl_esai: Fix TDM slot setup for I2S mode Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 09/37] net: ieee802154: stop dump llsec keys for monitors Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 10/37] net: ieee802154: stop dump llsec devs " Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 11/37] net: ieee802154: forbid monitor for add llsec dev Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 12/37] net: ieee802154: stop dump llsec devkeys for monitors Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 13/37] net: ieee802154: forbid monitor for add llsec devkey Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 14/37] net: ieee802154: stop dump llsec seclevels for monitors Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 15/37] net: ieee802154: forbid monitor for add llsec seclevel Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 16/37] pcnet32: Use pci_resource_len to validate PCI resource Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 17/37] Input: i8042 - fix Pegatron C15B ID entry Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 18/37] scsi: libsas: Reset num_scatter if libata marks qc as NODATA Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 19/37] net: davicom: Fix regulator not turned off on failed probe Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 20/37] net: sit: Unregister catch-all devices Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 21/37] i40e: fix the panic when running bpf in xdpdrv mode Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 22/37] ARM: 9071/1: uprobes: Dont hook on thumb instructions Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 23/37] usbip: Fix incorrect double assignment to udc->ud.tcp_rx Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 24/37] usbip: add sysfs_lock to synchronize sysfs code paths Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 25/37] usbip: stub-dev " Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 26/37] usbip: vudc " Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 27/37] usbip: synchronize event handler with " Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 28/37] net: hso: fix null-ptr-deref during tty device unregistration Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 29/37] ext4: correct error label in ext4_rename() Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 30/37] HID: alps: fix error return code in alps_input_configured() Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 31/37] ARM: dts: Fix swapped mmc order for omap3 Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 32/37] s390/entry: save the caller of psw_idle Greg Kroah-Hartman
2021-04-26 7:29 ` Greg Kroah-Hartman [this message]
2021-04-26 7:29 ` [PATCH 4.9 34/37] cavium/liquidio: Fix duplicate argument Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 35/37] ia64: fix discontig.c section mismatches Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 36/37] ia64: tools: remove duplicate definition of ia64_mf() on ia64 Greg Kroah-Hartman
2021-04-26 7:29 ` [PATCH 4.9 37/37] x86/crash: Fix crash_setup_memmap_entries() out-of-bounds access Greg Kroah-Hartman
2021-04-26 17:26 ` [PATCH 4.9 00/37] 4.9.268-rc1 review Florian Fainelli
2021-04-26 18:32 ` Guenter Roeck
2021-04-26 23:47 ` Shuah Khan
2021-04-27 7:36 ` Naresh Kamboju
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210426072818.365616663@linuxfoundation.org \
--to=gregkh@linuxfoundation.org \
--cc=davem@davemloft.net \
--cc=linux-kernel@vger.kernel.org \
--cc=mbrown@fensystems.co.uk \
--cc=paul@xen.org \
--cc=sashal@kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).