futex: race in lock and unlock&exit for robust futex with PI?

futex: race in lock and unlock&exit for robust futex with PI?

Post by Peter Zijl » Wed, 30 Jun 2010 01:50:02


n Mon, 2010-06-28 at 18:39 +0200, Michal Hocko wrote:

So it was Ingo, who in c87e2837be8 (pi-futex:
futex_lock_pi/futex_unlock_pi support) introduced the euid checks:

+futex_find_get_task():
+ if ((current->euid != p->euid) && (current->euid != p->uid)) {
+ p = NULL;
+ goto out_unlock;
+ }

Ingo, do you remember the rationale behind that? It seems to be causing
grief when two different users contend on the same (shared) futex.

See the below proposed solution.

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futex: race in lock and unlock&exit for robust futex with PI?

Post by Peter Zijl » Wed, 30 Jun 2010 01:50:03


You can lessen the burden on all of us by t *** your emails more
aggressively. Your last one has 4 dead tails in it.
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