[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] xenbus stress testing
How do you propose to lock against another VM updating a counter in shared memory? Paul > -----Original Message----- > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel- > bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Olaf Hering > Sent: 18 February 2011 11:05 > To: James Harper > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Ian Jackson > Subject: Re: [Xen-devel] xenbus stress testing > > On Fri, Feb 18, James Harper wrote: > > > I think I have found the error and it was probably a 1 in a > million > > race so stress testing might not have helped anyway. My code went: > > > > len = min(ring->rsp_prod - ring->rsp_cons, msg_size) > > > > and the ASSERT was hit because len was > msg_size, and the only > > possible way I can ever see that happening is if ring->rsp_prod > > changed between the if in the min() and the assignment. I'm now > > snapshotting rsp_prod to a local variable at the start. Kind of > > embarrassing really as plenty of example code exists. > > Why is there no lock to protect the ring accesses? > > Olaf > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxxxxxxxx > http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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