8f665c88c9
(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 Signed-off-by: Yoshitake Kobayashi <yoshitake.kobayashi@toshiba.co.jp> Cc: viro@zeniv.linux.org.uk Cc: dchinner@redhat.com Cc: npiggin@kernel.dk Cc: hch@lst.de Cc: arnd@arndb.de Link: http://lkml.kernel.org/r/4E2A38A0.1090601@toshiba.co.jp Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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.. | ||
Makefile | ||
compat.c | ||
compat_mq.c | ||
ipc_sysctl.c | ||
ipcns_notifier.c | ||
mq_sysctl.c | ||
mqueue.c | ||
msg.c | ||
msgutil.c | ||
namespace.c | ||
sem.c | ||
shm.c | ||
syscall.c | ||
util.c | ||
util.h |