On Thu, Mar 27, 2014 at 10:33 AM, Flavio Leitner <f...@redhat.com> wrote:
> On Thu, Mar 27, 2014 at 10:19:23AM -0700, Pravin Shelar wrote:
>> On Thu, Mar 27, 2014 at 7:05 AM, Flavio Leitner <f...@redhat.com> wrote:
>> > There are two problematic situations.
>> >
>> > A deadlock can happen when is_percpu is false because it can get
>> > interrupted while holding the spinlock. Then it executes
>> > ovs_flow_stats_update() in softirq context which tries to get
>> > the same lock.
>> >
>> > The second sitation is that when is_percpu is true, the code
>> > correctly disables BH but only for the local CPU, so the
>> > following can happen when locking the remote CPU without
>> > disabling BH:
>> >
>> > CPU#0 CPU#1
>> > ovs_flow_stats_get()
>> > stats_read()
>> > +->spin_lock remote CPU#1 ovs_flow_stats_get()
>> > | <interrupted> stats_read()
>> > | ... +--> spin_lock remote CPU#0
>> > | | <interrupted>
>> > | ovs_flow_stats_update() | ...
>> > | spin_lock local CPU#0 <--+ ovs_flow_stats_update()
>> > +---------------------------------- spin_lock local CPU#1
>> >
>> > This patch disables BH for both cases fixing the deadlocks.
>>
>> This bug is already fixed in OVS.
>
> Could you point me to the commit? I am not finding anything
> recent.
This is the commit:
commit 9d73c9cac76ba557fdac4a89c1b7eafe132b85a3
Author: Pravin B Shelar <pshe...@nicira.com>
Date: Tue Dec 17 15:43:30 2013 -0800
datapath: Fix deadlock during stats update.
I thought that I had sent it in the most recent batch of changes for
net but it looks like I missed it.
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