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Ingo Molnar 86998aa653 [PATCH] genirq core: fix handle_level_irq() 
while porting the -rt tree to 2.6.18-rc7 i noticed the following
screaming-IRQ scenario on an SMP system:

 2274  0Dn.:1 0.001ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.010ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.020ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.029ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.039ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.048ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.058ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.068ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.077ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.087ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)
 2274  0Dn.:1 0.097ms: do_IRQ+0xc/0x103  <= (ret_from_intr+0x0/0xf)

as it turns out, the bug is caused by handle_level_irq(), which if it
races with another CPU already handling this IRQ, it _unmasks_ the IRQ
line on the way out. This is not how 2.6.17 works, and we introduced
this bug in one of the early genirq cleanups right before it went into
-mm. (the bug was not in the genirq patchset for a long time, and we
didnt notice the bug due to the lack of -rt rebase to the new genirq
code. -rt, and hardirq-preemption in particular opens up such races much
wider than anything else.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-19 07:57:20 -07:00
..
irq [PATCH] genirq core: fix handle_level_irq() 2006-09-19 07:57:20 -07:00
power [PATCH] prevent swsusp with PAE 2006-09-06 11:00:02 -07:00
time
.gitignore
acct.c [PATCH] Fix sighand->siglock usage in kernel/acct.c 2006-07-14 21:53:54 -07:00
audit.c [PATCH] sanity check audit_buffer 2006-09-11 13:32:17 -04:00
audit.h [PATCH] audit: AUDIT_PERM support 2006-09-11 13:32:30 -04:00
auditfilter.c [PATCH] audit: AUDIT_PERM support 2006-09-11 13:32:30 -04:00
auditsc.c [PATCH] audit: AUDIT_PERM support 2006-09-11 13:32:30 -04:00
capability.c [PATCH] sched: cleanup, remove task_t, convert to struct task_struct 2006-07-03 15:27:11 -07:00
compat.c
configs.c
cpu.c cpu hotplug: simplify and hopefully fix locking 2006-07-23 12:12:16 -07:00
cpuset.c [PATCH] cpuset: oom panic fix 2006-08-27 11:01:32 -07:00
delayacct.c [PATCH] task delay accounting fixes 2006-09-01 11:39:08 -07:00
dma.c
exec_domain.c
exit.c [PATCH] eligible_child: remove an obsolete ->tgid check 2006-09-02 14:51:27 -07:00
extable.c
fork.c [PATCH] task delay accounting fixes 2006-09-01 11:39:08 -07:00
futex.c [PATCH] Use the correct restart option for futex_lock_pi 2006-09-08 10:22:50 -07:00
futex_compat.c [PATCH] futex: Apply recent futex fixes to futex_compat 2006-08-06 08:57:49 -07:00
hrtimer.c [PATCH] fix hrtimer percpu usage typo 2006-08-14 12:54:28 -07:00
itimer.c
kallsyms.c [PATCH] null-terminate over-long /proc/kallsyms symbols 2006-07-14 21:53:52 -07:00
Kconfig.hz
Kconfig.preempt
kexec.c
kfifo.c
kmod.c [PATCH] bug fix in kernel/kmod.c 2006-09-16 12:54:32 -07:00
kprobes.c [PATCH] IA64: kprobe invalidate icache of jump buffer 2006-07-31 13:28:38 -07:00
ksysfs.c
kthread.c [PATCH] remove kernel/kthread.c:kthread_stop_sem() 2006-07-14 21:53:52 -07:00
lockdep.c [PATCH] lockdep: core, reduce per-lock class-cache size 2006-07-10 13:24:14 -07:00
lockdep_internals.h [PATCH] lockdep: double the number of stack-trace entries 2006-09-13 07:32:14 -07:00
lockdep_proc.c [PATCH] lockdep: procfs 2006-07-03 15:27:04 -07:00
Makefile [PATCH] per-task-delay-accounting: taskstats interface 2006-07-14 21:53:56 -07:00
module.c [PATCH] null-terminate over-long /proc/kallsyms symbols 2006-07-14 21:53:52 -07:00
mutex-debug.c [PATCH] lockdep: prove mutex locking correctness 2006-07-03 15:27:04 -07:00
mutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
mutex.c [PATCH] lockdep: prove mutex locking correctness 2006-07-03 15:27:04 -07:00
mutex.h [PATCH] lockdep: prove mutex locking correctness 2006-07-03 15:27:04 -07:00
panic.c [PATCH] lockdep: do not touch console state when tainting the kernel 2006-09-06 11:00:02 -07:00
params.c
pid.c [PATCH] sched: cleanup, remove task_t, convert to struct task_struct 2006-07-03 15:27:11 -07:00
posix-cpu-timers.c
posix-timers.c
printk.c [PATCH] vt: printk: Fix framebuffer console triggering might_sleep assertion 2006-08-06 08:57:47 -07:00
profile.c
ptrace.c [PATCH] sched: cleanup, remove task_t, convert to struct task_struct 2006-07-03 15:27:11 -07:00
rcupdate.c [PATCH] rcu_do_batch: make ->qlen decrement irq safe 2006-09-13 07:32:14 -07:00
rcutorture.c
relay.c
resource.c [PATCH] memory hotadd fixes: find_next_system_ram catch range fix 2006-08-06 08:57:48 -07:00
rtmutex-debug.c [PATCH] sched: cleanup, remove task_t, convert to struct task_struct 2006-07-03 15:27:11 -07:00
rtmutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex-tester.c [PATCH] Add try_to_freeze() to rt-test kthreads 2006-07-14 21:53:53 -07:00
rtmutex.c [PATCH] reference rt-mutex-design in rtmutex.c 2006-07-31 13:28:43 -07:00
rtmutex.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex_common.h
rwsem.c [PATCH] lockdep: prove rwsem locking correctness 2006-07-03 15:27:04 -07:00
sched.c [PATCH] revert "Drop tasklist lock in do_sched_setscheduler" 2006-08-27 11:01:29 -07:00
seccomp.c
signal.c Fix force_sig_info() semantics after cleanups 2006-08-02 20:17:49 -07:00
softirq.c [PATCH] Reducing local_bh_enable/disable overhead in irqtrace 2006-07-31 13:28:42 -07:00
softlockup.c [PATCH] cpu hotplug: replace __devinit* with __cpuinit* for cpu notifications 2006-07-31 13:28:39 -07:00
spinlock.c [PATCH] lockdep ifdef fix 2006-09-06 11:00:01 -07:00
stacktrace.c [PATCH] lockdep: stacktrace subsystem, core 2006-07-03 15:27:02 -07:00
stop_machine.c [PATCH] Remove redundant up() in stop_machine() 2006-08-27 11:01:31 -07:00
sys.c [PATCH] Fix prctl privilege escalation and suid_dumpable (CVE-2006-2451) 2006-07-12 12:50:25 -07:00
sys_ni.c
sysctl.c [PATCH] ZVC/zone_reclaim: Leave 1% of unmapped pagecache pages for file I/O 2006-07-03 15:26:59 -07:00
taskstats.c [PATCH] taskstats: free skb, avoid returns in send_cpu_listeners 2006-07-31 13:28:37 -07:00
time.c
timer.c [PATCH] sys_getppid oopses on debug kernel 2006-08-14 12:54:29 -07:00
uid16.c
unwind.c
user.c
wait.c [PATCH] uninline init_waitqueue_head() 2006-07-10 13:24:25 -07:00
workqueue.c [PATCH] workqueue: remove lock_cpu_hotplug() 2006-08-14 12:54:29 -07:00