[Gluster-devel] pthread_mutex misusage in glusterd_op_sm

[Emmanuel Dreyfus]

I made a simple fix that address the problem:
http://review.gluster.org/9197

Are there other places where the same bug could exist? Anyone familiar
with the code would tell?

Emmanuel Dreyfus <manu at netbsd.org> wrote:

> in glusterd_op_sm(), we lock and unlock the gd_op_sm_lock mutex. 
> Unfortunately, locking and unlocking can happen in different threads
> (task swap will occur in handelr call).
> 
> This case is explictely covered by POSIX: the behavior is undefined.
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_lo
> ck.html
> 
> When unlocking from a thread that is not owner, Linux seems to be fine
> (though you never know with unspecified operation), while NetBSD returns
> EPERM, causing a spurious error in tests/basic/pump.t . It can be observed
> in a few failed tests here:
> http://build.gluster.org/job/rackspace-netbsd7-regression-triggered/
> 
> Fixing it seems far from being obvious. I guess it needs to use syncop,
> but the change would be intrusive. Do we have another option? Is it 
> possible to switch a task to a given thread?


-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu at netbsd.org