* [PATCH] xen-netback: fix a BUG() during initialization
@ 2015-06-19 12:21 Imre Palik
0 siblings, 0 replies; 8+ messages in thread
From: Imre Palik @ 2015-06-19 12:21 UTC (permalink / raw
To: xen-devel, Ian Campbell, Wei Liu
Cc: netdev, Palik, Imre, linux-kernel, Matt Wilson
From: "Palik, Imre" <imrep@amazon.de>
Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
introduced the capability to change the bandwidth rate limit at runtime.
But it also introduced a possible crashing bug.
If netback receives two XenbusStateConnected without getting the
hotplug-status watch firing in between, then it will try to register the
watches for the rate limiter again. But this triggers a BUG() in the watch
registration code.
The fix modifies connect() to remove the possibly existing packet-rate
watches before trying to install those watches. This behaviour is in line
with how connect() deals with the hotplug-status watch.
Signed-off-by: Imre Palik <imrep@amazon.de>
Cc: Matt Wilson <msw@amazon.com>
---
drivers/net/xen-netback/xenbus.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 968787a..ec383b0 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -681,6 +681,9 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
char *node;
unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
+ if (vif->credit_watch.node)
+ return -EADDRINUSE;
+
node = kmalloc(maxlen, GFP_KERNEL);
if (!node)
return -ENOMEM;
@@ -770,6 +773,7 @@ static void connect(struct backend_info *be)
}
xen_net_read_rate(dev, &credit_bytes, &credit_usec);
+ xen_unregister_watchers(be->vif);
xen_register_watchers(dev, be->vif);
read_xenbus_vif_flags(be);
--
1.7.9.5
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH] xen-netback: fix a BUG() during initialization
@ 2015-06-19 12:21 ` Imre Palik
0 siblings, 0 replies; 8+ messages in thread
From: Imre Palik @ 2015-06-19 12:21 UTC (permalink / raw
To: xen-devel, Ian Campbell, Wei Liu
Cc: netdev, linux-kernel, Palik, Imre, Matt Wilson
From: "Palik, Imre" <imrep@amazon.de>
Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
introduced the capability to change the bandwidth rate limit at runtime.
But it also introduced a possible crashing bug.
If netback receives two XenbusStateConnected without getting the
hotplug-status watch firing in between, then it will try to register the
watches for the rate limiter again. But this triggers a BUG() in the watch
registration code.
The fix modifies connect() to remove the possibly existing packet-rate
watches before trying to install those watches. This behaviour is in line
with how connect() deals with the hotplug-status watch.
Signed-off-by: Imre Palik <imrep@amazon.de>
Cc: Matt Wilson <msw@amazon.com>
---
drivers/net/xen-netback/xenbus.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 968787a..ec383b0 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -681,6 +681,9 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
char *node;
unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
+ if (vif->credit_watch.node)
+ return -EADDRINUSE;
+
node = kmalloc(maxlen, GFP_KERNEL);
if (!node)
return -ENOMEM;
@@ -770,6 +773,7 @@ static void connect(struct backend_info *be)
}
xen_net_read_rate(dev, &credit_bytes, &credit_usec);
+ xen_unregister_watchers(be->vif);
xen_register_watchers(dev, be->vif);
read_xenbus_vif_flags(be);
--
1.7.9.5
--
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^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH] xen-netback: fix a BUG() during initialization
@ 2015-06-19 12:21 ` Imre Palik
0 siblings, 0 replies; 8+ messages in thread
From: Imre Palik @ 2015-06-19 12:21 UTC (permalink / raw
To: xen-devel, Ian Campbell, Wei Liu
Cc: netdev, linux-kernel, Palik, Imre, Matt Wilson
From: "Palik, Imre" <imrep@amazon.de>
Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
introduced the capability to change the bandwidth rate limit at runtime.
But it also introduced a possible crashing bug.
If netback receives two XenbusStateConnected without getting the
hotplug-status watch firing in between, then it will try to register the
watches for the rate limiter again. But this triggers a BUG() in the watch
registration code.
The fix modifies connect() to remove the possibly existing packet-rate
watches before trying to install those watches. This behaviour is in line
with how connect() deals with the hotplug-status watch.
Signed-off-by: Imre Palik <imrep@amazon.de>
Cc: Matt Wilson <msw@amazon.com>
---
drivers/net/xen-netback/xenbus.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 968787a..ec383b0 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -681,6 +681,9 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
char *node;
unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
+ if (vif->credit_watch.node)
+ return -EADDRINUSE;
+
node = kmalloc(maxlen, GFP_KERNEL);
if (!node)
return -ENOMEM;
@@ -770,6 +773,7 @@ static void connect(struct backend_info *be)
}
xen_net_read_rate(dev, &credit_bytes, &credit_usec);
+ xen_unregister_watchers(be->vif);
xen_register_watchers(dev, be->vif);
read_xenbus_vif_flags(be);
--
1.7.9.5
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-netback: fix a BUG() during initialization
2015-06-19 12:21 ` Imre Palik
@ 2015-06-19 15:37 ` Wei Liu
-1 siblings, 0 replies; 8+ messages in thread
From: Wei Liu @ 2015-06-19 15:37 UTC (permalink / raw
To: Imre Palik
Cc: xen-devel, Ian Campbell, Wei Liu, netdev, linux-kernel,
Palik, Imre, Matt Wilson
On Fri, Jun 19, 2015 at 02:21:51PM +0200, Imre Palik wrote:
> From: "Palik, Imre" <imrep@amazon.de>
>
> Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
> introduced the capability to change the bandwidth rate limit at runtime.
> But it also introduced a possible crashing bug.
>
> If netback receives two XenbusStateConnected without getting the
> hotplug-status watch firing in between, then it will try to register the
> watches for the rate limiter again. But this triggers a BUG() in the watch
> registration code.
>
> The fix modifies connect() to remove the possibly existing packet-rate
> watches before trying to install those watches. This behaviour is in line
> with how connect() deals with the hotplug-status watch.
>
> Signed-off-by: Imre Palik <imrep@amazon.de>
> Cc: Matt Wilson <msw@amazon.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
> ---
> drivers/net/xen-netback/xenbus.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
> index 968787a..ec383b0 100644
> --- a/drivers/net/xen-netback/xenbus.c
> +++ b/drivers/net/xen-netback/xenbus.c
> @@ -681,6 +681,9 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
> char *node;
> unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
>
> + if (vif->credit_watch.node)
> + return -EADDRINUSE;
> +
> node = kmalloc(maxlen, GFP_KERNEL);
> if (!node)
> return -ENOMEM;
> @@ -770,6 +773,7 @@ static void connect(struct backend_info *be)
> }
>
> xen_net_read_rate(dev, &credit_bytes, &credit_usec);
> + xen_unregister_watchers(be->vif);
> xen_register_watchers(dev, be->vif);
> read_xenbus_vif_flags(be);
>
> --
> 1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-netback: fix a BUG() during initialization
@ 2015-06-19 15:37 ` Wei Liu
0 siblings, 0 replies; 8+ messages in thread
From: Wei Liu @ 2015-06-19 15:37 UTC (permalink / raw
To: Imre Palik
Cc: xen-devel, Ian Campbell, Wei Liu, netdev, linux-kernel,
Palik, Imre, Matt Wilson
On Fri, Jun 19, 2015 at 02:21:51PM +0200, Imre Palik wrote:
> From: "Palik, Imre" <imrep@amazon.de>
>
> Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
> introduced the capability to change the bandwidth rate limit at runtime.
> But it also introduced a possible crashing bug.
>
> If netback receives two XenbusStateConnected without getting the
> hotplug-status watch firing in between, then it will try to register the
> watches for the rate limiter again. But this triggers a BUG() in the watch
> registration code.
>
> The fix modifies connect() to remove the possibly existing packet-rate
> watches before trying to install those watches. This behaviour is in line
> with how connect() deals with the hotplug-status watch.
>
> Signed-off-by: Imre Palik <imrep@amazon.de>
> Cc: Matt Wilson <msw@amazon.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
> ---
> drivers/net/xen-netback/xenbus.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
> index 968787a..ec383b0 100644
> --- a/drivers/net/xen-netback/xenbus.c
> +++ b/drivers/net/xen-netback/xenbus.c
> @@ -681,6 +681,9 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
> char *node;
> unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
>
> + if (vif->credit_watch.node)
> + return -EADDRINUSE;
> +
> node = kmalloc(maxlen, GFP_KERNEL);
> if (!node)
> return -ENOMEM;
> @@ -770,6 +773,7 @@ static void connect(struct backend_info *be)
> }
>
> xen_net_read_rate(dev, &credit_bytes, &credit_usec);
> + xen_unregister_watchers(be->vif);
> xen_register_watchers(dev, be->vif);
> read_xenbus_vif_flags(be);
>
> --
> 1.7.9.5
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-netback: fix a BUG() during initialization
2015-06-19 12:21 ` Imre Palik
(?)
(?)
@ 2015-06-19 15:37 ` Wei Liu
-1 siblings, 0 replies; 8+ messages in thread
From: Wei Liu @ 2015-06-19 15:37 UTC (permalink / raw
To: Imre Palik
Cc: Palik, Imre, Wei Liu, Ian Campbell, netdev, linux-kernel,
Matt Wilson, xen-devel
On Fri, Jun 19, 2015 at 02:21:51PM +0200, Imre Palik wrote:
> From: "Palik, Imre" <imrep@amazon.de>
>
> Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
> introduced the capability to change the bandwidth rate limit at runtime.
> But it also introduced a possible crashing bug.
>
> If netback receives two XenbusStateConnected without getting the
> hotplug-status watch firing in between, then it will try to register the
> watches for the rate limiter again. But this triggers a BUG() in the watch
> registration code.
>
> The fix modifies connect() to remove the possibly existing packet-rate
> watches before trying to install those watches. This behaviour is in line
> with how connect() deals with the hotplug-status watch.
>
> Signed-off-by: Imre Palik <imrep@amazon.de>
> Cc: Matt Wilson <msw@amazon.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
> ---
> drivers/net/xen-netback/xenbus.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
> index 968787a..ec383b0 100644
> --- a/drivers/net/xen-netback/xenbus.c
> +++ b/drivers/net/xen-netback/xenbus.c
> @@ -681,6 +681,9 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
> char *node;
> unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
>
> + if (vif->credit_watch.node)
> + return -EADDRINUSE;
> +
> node = kmalloc(maxlen, GFP_KERNEL);
> if (!node)
> return -ENOMEM;
> @@ -770,6 +773,7 @@ static void connect(struct backend_info *be)
> }
>
> xen_net_read_rate(dev, &credit_bytes, &credit_usec);
> + xen_unregister_watchers(be->vif);
> xen_register_watchers(dev, be->vif);
> read_xenbus_vif_flags(be);
>
> --
> 1.7.9.5
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-netback: fix a BUG() during initialization
2015-06-19 12:21 ` Imre Palik
` (2 preceding siblings ...)
(?)
@ 2015-06-23 10:34 ` David Miller
-1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2015-06-23 10:34 UTC (permalink / raw
To: imrep.amz
Cc: xen-devel, ian.campbell, wei.liu2, netdev, linux-kernel, imrep,
msw
From: Imre Palik <imrep.amz@gmail.com>
Date: Fri, 19 Jun 2015 14:21:51 +0200
> From: "Palik, Imre" <imrep@amazon.de>
>
> Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
> introduced the capability to change the bandwidth rate limit at runtime.
> But it also introduced a possible crashing bug.
>
> If netback receives two XenbusStateConnected without getting the
> hotplug-status watch firing in between, then it will try to register the
> watches for the rate limiter again. But this triggers a BUG() in the watch
> registration code.
>
> The fix modifies connect() to remove the possibly existing packet-rate
> watches before trying to install those watches. This behaviour is in line
> with how connect() deals with the hotplug-status watch.
>
> Signed-off-by: Imre Palik <imrep@amazon.de>
> Cc: Matt Wilson <msw@amazon.com>
Applied, thank you.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] xen-netback: fix a BUG() during initialization
2015-06-19 12:21 ` Imre Palik
` (3 preceding siblings ...)
(?)
@ 2015-06-23 10:34 ` David Miller
-1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2015-06-23 10:34 UTC (permalink / raw
To: imrep.amz
Cc: imrep, wei.liu2, ian.campbell, netdev, linux-kernel, msw,
xen-devel
From: Imre Palik <imrep.amz@gmail.com>
Date: Fri, 19 Jun 2015 14:21:51 +0200
> From: "Palik, Imre" <imrep@amazon.de>
>
> Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
> introduced the capability to change the bandwidth rate limit at runtime.
> But it also introduced a possible crashing bug.
>
> If netback receives two XenbusStateConnected without getting the
> hotplug-status watch firing in between, then it will try to register the
> watches for the rate limiter again. But this triggers a BUG() in the watch
> registration code.
>
> The fix modifies connect() to remove the possibly existing packet-rate
> watches before trying to install those watches. This behaviour is in line
> with how connect() deals with the hotplug-status watch.
>
> Signed-off-by: Imre Palik <imrep@amazon.de>
> Cc: Matt Wilson <msw@amazon.com>
Applied, thank you.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2015-06-23 10:22 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
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2015-06-19 12:21 [PATCH] xen-netback: fix a BUG() during initialization Imre Palik
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2015-06-19 12:21 Imre Palik
2015-06-19 12:21 ` Imre Palik
2015-06-19 15:37 ` Wei Liu
2015-06-19 15:37 ` Wei Liu
2015-06-19 15:37 ` Wei Liu
2015-06-23 10:34 ` David Miller
2015-06-23 10:34 ` David Miller
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