Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.1 13/56] xen-netback: fix a BUG() during initialization | Date | Wed, 8 Jul 2015 00:35:02 -0700 |
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4.1-stable review patch. If anyone has any objections, please let me know.
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From: "Palik, Imre" <imrep@amazon.de>
[ Upstream commit 12b322ac85208de564ecf23aa754d796a91de21f ]
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> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/net/xen-netback/xenbus.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -681,6 +681,9 @@ static int xen_register_watchers(struct 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 } 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);
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