Commit:     98d8256739f2c6c636fa2da359f5949c739ae839
Parent:     40acc095302aee380491df5f58d98945243468ec
Author:     Thomas Gleixner <[EMAIL PROTECTED]>
AuthorDate: Wed May 23 13:58:18 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed May 23 20:14:15 2007 -0700

    Prevent going idle with softirq pending
    The NOHZ patch contains a check for softirqs pending when a CPU goes idle.
    The BUG is unrelated to NOHZ, it just was made visible by the NOHZ patch.
    The BUG showed up mainly on P4 / hyperthreading enabled machines which lead
    the investigations into the wrong direction in the first place.  The real
    cause is in cond_resched_softirq():
    cond_resched_softirq() is enabling softirqs without invoking the softirq
    daemon when softirqs are pending.  This leads to the warning message in the
    NOHZ idle code:
    t1 runs softirq disabled code on CPU#0
    interrupt happens, softirq is raised, but deferred (softirqs disabled)
    t1 calls cond_resched_softirq()
        enables softirqs via _local_bh_enable()
        calls schedule()
    t2 runs
    t1 is migrated to CPU#1
    t2 is done and invokes idle()
    NOHZ detects the pending softirq
    Fix: change _local_bh_enable() to local_bh_enable() so the softirq
    daemon is invoked.
    Thanks to Anant Nitya for debugging this with great patience !
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 kernel/sched.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 799d23b..13cdab3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4775,9 +4775,7 @@ int __sched cond_resched_softirq(void)
        if (need_resched() && system_state == SYSTEM_RUNNING) {
-               raw_local_irq_disable();
-               _local_bh_enable();
-               raw_local_irq_enable();
+               local_bh_enable();
                return 1;
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