On Sat, 23 Jul 2011, KOBAYASHI Yoshitake wrote: > (Repost for v3.0-rt1 and changed the distination addreses) > I have tested the following patch on v3.0-rt1 with PREEMPT_RT_FULL. > In POSIX message queue, if a sender process uses SCHED_FIFO and > has a higher priority than a receiver process, the sender will > be stuck at ipc/mqueue.c:452 > > 452 while (ewp->state == STATE_PENDING) > 453 cpu_relax(); > > Description of the problem > (receiver process) > 1. receiver changes sender's state to STATE_PENDING (mqueue.c:846) > 2. wake up sender process and "switch to sender" (mqueue.c:847) > Note: This context switch only happens in PREEMPT_RT_FULL kernel. > (sender process) > 3. sender check the own state in above loop (mqueue.c:452-453) > *. receiver will never wake up and cannot change sender's state to > STATE_READY because sender has higher priority Good catch! Queued for -rt2. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
