Re: [PATCH v2] net: fix sleeping while atomic problem in sock mem_cgroup.

[Glauber Costa]

On 12/16/2011 02:04 PM, Eric Dumazet wrote:
> Le vendredi 16 dÃcembre 2011 Ã 13:53 +0400, Glauber Costa a Ãcrit :
> > On 12/16/2011 01:31 PM, Eric Dumazet wrote:
> > > Le vendredi 16 dÃcembre 2011 Ã 13:09 +0400, Glauber Costa a Ãcrit :
> > > > Since we can't scan the proto_list to initialize sock cgroups, as it
> > > > holds a rwlock, and we also want to keep the code generic enough to
> > > > avoid calling the initialization functions of protocols directly,
> > > > I propose we keep the interested parties in a separate list. This list
> > > > is protected by a mutex so we can sleep and do the necessary allocations.
> > > >
> > > > Also fixes a reference problem found by Randy Dunlap's randconfig.
> > > >
> > > > Signed-off-by: Glauber Costa<glommer@xxxxxxxxxxxxx>
> > > > CC: Hiroyouki Kamezawa<kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > > > CC: David S. Miller<davem@xxxxxxxxxxxxx>
> > > > CC: Eric Dumazet<eric.dumazet@xxxxxxxxx>
> > > > CC: Stephen Rothwell<sfr@xxxxxxxxxxxxxxxx>
> > > > CC: Randy Dunlap<rdunlap@xxxxxxxxxxxx>
> > > > ---
> > >
> > > Sorry to come late, but why dont we convert proto_list_lock to a mutex ?
> >
> > I didn't suggest this, as I imagined there could be some performance
> > implications to be drawn from it that may not be obvious to me.
> >
> > But if it is okay with you net guys, it is certainly okay with me as well.
>
> This 'lock' is not performance sensitive, its very seldom taken.
>
> If we really wanted to be fast, it would not be a rwlock anymore ;)
>
> "cat /proc/net/protocols" could eventually use RCU locking if we want
> parallelism. (I dont think its needed)

Well, in this case, I myself think this is a better solution. Do you 
want to push the patch yourself, or should I do it ?


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