[PATCH v2 1/2] Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"
This reverts commit 1f2565780e9b7218cf92c7630130e82dcc0fe9c2.
The 'hotplug-status' node should not be removed as long as the vif device remains configured. Otherwise the xen-netback would wait for re-running the network script even if it was already called (in case of the frontent re-connecting). But also, it _should_ be removed when the vif device is destroyed (for example when unbinding the driver) - otherwise hotplug script would not configure the device whenever it re-appear.
Moving removal of the 'hotplug-status' node was a workaround for nothing calling network script after xen-netback module is reloaded. But when vif interface is re-created (on xen-netback unbind/bind for example), the script should be called, regardless of who does that - currently this case is not handled by the toolstack, and requires manual script call. Keeping hotplug-status=connected to skip the call is wrong and leads to not configured interface.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com --- Cc: Michael Brown mcb30@ipxe.org Changes in v2: - build fix, reported by kernel test robot lkp@intel.com
--- drivers/net/xen-netback/xenbus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index d24b7a7993aa..3fad58d22155 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -256,6 +256,7 @@ static void backend_disconnect(struct backend_info *be) unsigned int queue_index;
xen_unregister_watchers(vif); + xenbus_rm(XBT_NIL, be->dev->nodename, "hotplug-status"); #ifdef CONFIG_DEBUG_FS xenvif_debugfs_delif(vif); #endif /* CONFIG_DEBUG_FS */ @@ -675,7 +676,6 @@ static void hotplug_status_changed(struct xenbus_watch *watch,
/* Not interested in this watch anymore. */ unregister_hotplug_status_watch(be); - xenbus_rm(XBT_NIL, be->dev->nodename, "hotplug-status"); } kfree(str); }
This reverts commit 2afeec08ab5c86ae21952151f726bfe184f6b23d.
The reasoning in the commit was wrong - the code expected to setup the watch even if 'hotplug-status' didn't exist. In fact, it relied on the watch being fired the first time - to check if maybe 'hotplug-status' is already set to 'connected'. Not registering a watch for non-existing path (which is the case if hotplug script hasn't been executed yet), made the backend not waiting for the hotplug script to execute. This in turns, made the netfront think the interface is fully operational, while in fact it was not (the vif interface on xen-netback side might not be configured yet).
This was a workaround for 'hotplug-status' erroneously being removed. But since that is reverted now, the workaround is not necessary either.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com --- I believe this is the same issue as discussed at https://lore.kernel.org/xen-devel/20220113111946.GA4133739@dingwall.me.uk/ Cc: James Dingwall <james-xen@dingwall.me.uk Cc: Michael Brown mcb30@ipxe.org --- drivers/net/xen-netback/xenbus.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index 3fad58d22155..990360d75cb6 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -824,15 +824,11 @@ static void connect(struct backend_info *be) xenvif_carrier_on(be->vif);
unregister_hotplug_status_watch(be); - 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; + err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch, NULL, + hotplug_status_changed, + "%s/%s", dev->nodename, "hotplug-status"); + if (!err) be->have_hotplug_status_watch = 1; - }
netif_tx_wake_all_queues(be->vif->dev);
On Tue, Feb 22, 2022 at 01:18:17AM +0100, Marek Marczykowski-Górecki wrote:
This reverts commit 2afeec08ab5c86ae21952151f726bfe184f6b23d.
The reasoning in the commit was wrong - the code expected to setup the watch even if 'hotplug-status' didn't exist. In fact, it relied on the watch being fired the first time - to check if maybe 'hotplug-status' is already set to 'connected'. Not registering a watch for non-existing path (which is the case if hotplug script hasn't been executed yet), made the backend not waiting for the hotplug script to execute. This in turns, made the netfront think the interface is fully operational, while in fact it was not (the vif interface on xen-netback side might not be configured yet).
This was a workaround for 'hotplug-status' erroneously being removed. But since that is reverted now, the workaround is not necessary either.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
I believe this is the same issue as discussed at https://lore.kernel.org/xen-devel/20220113111946.GA4133739@dingwall.me.uk/
Right - I believe we need to leave that workaround in place in libxl in order to deal with bogus Linux netbacks?
Thanks, Roger.
On Tue, Feb 22, 2022 at 09:31:31AM +0100, Roger Pau Monné wrote:
On Tue, Feb 22, 2022 at 01:18:17AM +0100, Marek Marczykowski-Górecki wrote:
This reverts commit 2afeec08ab5c86ae21952151f726bfe184f6b23d.
The reasoning in the commit was wrong - the code expected to setup the watch even if 'hotplug-status' didn't exist. In fact, it relied on the watch being fired the first time - to check if maybe 'hotplug-status' is already set to 'connected'. Not registering a watch for non-existing path (which is the case if hotplug script hasn't been executed yet), made the backend not waiting for the hotplug script to execute. This in turns, made the netfront think the interface is fully operational, while in fact it was not (the vif interface on xen-netback side might not be configured yet).
This was a workaround for 'hotplug-status' erroneously being removed. But since that is reverted now, the workaround is not necessary either.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
I believe this is the same issue as discussed at https://lore.kernel.org/xen-devel/20220113111946.GA4133739@dingwall.me.uk/
Right - I believe we need to leave that workaround in place in libxl in order to deal with bogus Linux netbacks?
I'm afraid so, yes.
On 22/02/2022 00:18, Marek Marczykowski-Górecki wrote:
This reverts commit 2afeec08ab5c86ae21952151f726bfe184f6b23d.
The reasoning in the commit was wrong - the code expected to setup the watch even if 'hotplug-status' didn't exist. In fact, it relied on the watch being fired the first time - to check if maybe 'hotplug-status' is already set to 'connected'. Not registering a watch for non-existing path (which is the case if hotplug script hasn't been executed yet), made the backend not waiting for the hotplug script to execute. This in turns, made the netfront think the interface is fully operational, while in fact it was not (the vif interface on xen-netback side might not be configured yet).
This was a workaround for 'hotplug-status' erroneously being removed. But since that is reverted now, the workaround is not necessary either.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
Reviewed-by: Paul Durrant paul@xen.org
On 24/02/2022 07:56, Durrant, Paul wrote:
On 22/02/2022 00:18, Marek Marczykowski-Górecki wrote:
This reverts commit 2afeec08ab5c86ae21952151f726bfe184f6b23d.
The reasoning in the commit was wrong - the code expected to setup the watch even if 'hotplug-status' didn't exist. In fact, it relied on the watch being fired the first time - to check if maybe 'hotplug-status' is already set to 'connected'. Not registering a watch for non-existing path (which is the case if hotplug script hasn't been executed yet), made the backend not waiting for the hotplug script to execute. This in turns, made the netfront think the interface is fully operational, while in fact it was not (the vif interface on xen-netback side might not be configured yet).
This was a workaround for 'hotplug-status' erroneously being removed. But since that is reverted now, the workaround is not necessary either.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
Reviewed-by: Paul Durrant paul@xen.org
In conjunction with patch 1/2 (which reverts the patch that caused the original problem):
Reviewed-by: Michael Brown mbrown@fensystems.co.uk
Thanks,
Michael
On Tue, 22 Feb 2022 01:18:16 +0100 Marek Marczykowski-Górecki wrote:
This reverts commit 1f2565780e9b7218cf92c7630130e82dcc0fe9c2.
The 'hotplug-status' node should not be removed as long as the vif device remains configured. Otherwise the xen-netback would wait for re-running the network script even if it was already called (in case of the frontent re-connecting). But also, it _should_ be removed when the vif device is destroyed (for example when unbinding the driver) - otherwise hotplug script would not configure the device whenever it re-appear.
Moving removal of the 'hotplug-status' node was a workaround for nothing calling network script after xen-netback module is reloaded. But when vif interface is re-created (on xen-netback unbind/bind for example), the script should be called, regardless of who does that - currently this case is not handled by the toolstack, and requires manual script call. Keeping hotplug-status=connected to skip the call is wrong and leads to not configured interface.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
Wei, Paul, do these look good?
On 22/02/2022 00:18, Marek Marczykowski-Górecki wrote:
This reverts commit 1f2565780e9b7218cf92c7630130e82dcc0fe9c2.
The 'hotplug-status' node should not be removed as long as the vif device remains configured. Otherwise the xen-netback would wait for re-running the network script even if it was already called (in case of the frontent re-connecting). But also, it _should_ be removed when the vif device is destroyed (for example when unbinding the driver) - otherwise hotplug script would not configure the device whenever it re-appear.
Moving removal of the 'hotplug-status' node was a workaround for nothing calling network script after xen-netback module is reloaded. But when vif interface is re-created (on xen-netback unbind/bind for example), the script should be called, regardless of who does that - currently this case is not handled by the toolstack, and requires manual script call. Keeping hotplug-status=connected to skip the call is wrong and leads to not configured interface.
More discussion at https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe....
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
Reviewed-by: Paul Durrant paul@xen.org
Hello:
This series was applied to netdev/net.git (master) by Jakub Kicinski kuba@kernel.org:
On Tue, 22 Feb 2022 01:18:16 +0100 you wrote:
This reverts commit 1f2565780e9b7218cf92c7630130e82dcc0fe9c2.
The 'hotplug-status' node should not be removed as long as the vif device remains configured. Otherwise the xen-netback would wait for re-running the network script even if it was already called (in case of the frontent re-connecting). But also, it _should_ be removed when the vif device is destroyed (for example when unbinding the driver) - otherwise hotplug script would not configure the device whenever it re-appear.
[...]
Here is the summary with links: - [v2,1/2] Revert "xen-netback: remove 'hotplug-status' once it has served its purpose" https://git.kernel.org/netdev/net/c/0f4558ae9187 - [v2,2/2] Revert "xen-netback: Check for hotplug-status existence before watching" https://git.kernel.org/netdev/net/c/e8240addd0a3
You are awesome, thank you!
linux-stable-mirror@lists.linaro.org
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Durrant, Paul -
Jakub Kicinski -
Marek Marczykowski-Górecki -
Michael Brown -
patchwork-bot+netdevbpf＠kernel.org -
Roger Pau Monné