[ovs-dev] [PATCH] lacp: Really fix mutex initialization.

Ben Pfaff blp at nicira.com
Wed May 7 20:13:54 UTC 2014

On Wed, May 07, 2014 at 01:01:56PM -0700, Andy Zhou wrote:
> On Wed, May 7, 2014 at 12:13 PM, Andy Zhou <azhou at nicira.com> wrote:
> > I am looking at it.
> >
> > On Tue, May 6, 2014 at 12:50 PM, Ben Pfaff <blp at nicira.com> wrote:
> >> Commit 2a3fb0aa3c (lacp: Don't lock potentially uninitialized mutex in
> >> lacp_status().) fixed one bug related to acquiring the file scope 'mutex'
> >> without initializing it.  However, there was at least one other, in
> >> lacp_unixctl_show().  One could just fix that one problem, but that leaves
> >> the possibility that I might have missed one or two more.  This commit
> >> fixes the problem for good, by adding a helper that initializes the mutex
> >> and then acquires it.
> This makes the lacp locking somewhat different from other modules.
> The logic looks fine.
> Acked-by: Andy Zhou <azhou at nicira.com>


I think it's OK for the locking to be a little different here.

> >> It's not entirely clear why 'mutex' is a recursive mutex.  I think that it
> >> might be just because of the callback in lacp_run().  An alternate fix,
> >> therefore, would be to eliminate the callback and therefore the need for
> >> runtime initialization of the mutex.
> It seems when we send a lacp packet out while holding the mutex,
> compose_output_action__ could
> send it right back lacp via process_special().  May be we can queue up
> the packets in lacp_run,
> and call send_pdu outside of lock?

Yes, that's what I concluded too.

I'll push this in a minute.

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