[dpdk-dev] [memnic PATCH v2] pmd: fix race condition
Thomas Monjalon
thomas.monjalon at 6wind.com
Fri Apr 11 17:46:24 CEST 2014
2014-04-11 16:41, Olivier MATZ:
> On Thursday, April 03, 2014 06:35:06 AM Hiroshi Shimamoto wrote:
> > From: Hiroshi Shimamoto <h-shimamoto at ct.jp.nec.com>
> >
> > There is a race condition, on transmit to host.
> >
> > Guest PMD Host
> > Thread-A Thread-B vSwitch
> >
> > |idx=0 |idx=0 |p[0] st!=2
> > |cmpxchg | |
> > |p[0] st->1 | |
> > |idx=1 | |
> > |fill data | |
> > |p[0] st->2 | |p[0] st==2
> > |
> > | | |receive data
> > | | |p[0] st->0
> > | |
> > | |cmpxchg |
> > | |success |p[1] st!=2
> > | |p[0] st->1 |
> > | |
> > This is BAD
> >
> > That causes traffic stop.
> >
> > We have to take care about that race condition with checking
> > whether current index is correct.
> >
> > Signed-off-by: Hiroshi Shimamoto <h-shimamoto at ct.jp.nec.com>
> > Reviewed-by: Hayato Momma <h-momma at ce.jp.nec.com>
>
> Reviewed-by: Olivier Matz <olivier.matz at 6wind.com>
Applied
Thanks
--
Thomas
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