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a69ac4a78d
kernel-ark/kernel
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Oleg Nesterov a69ac4a78d [PATCH] posix-timers: fix posix_cpu_timer_set() vs run_posix_cpu_timers() race 
This might be harmless, but looks like a race from code inspection (I
was unable to trigger it).  I must admit, I don't understand why we
can't return TIMER_RETRY after 'spin_unlock(&p->sighand->siglock)'
without doing bump_cpu_timer(), but this is what original code does.

posix_cpu_timer_set:

	read_lock(&tasklist_lock);

	spin_lock(&p->sighand->siglock);
	list_del_init(&timer->it.cpu.entry);
	spin_unlock(&p->sighand->siglock);

We are probaly deleting the timer from run_posix_cpu_timers's 'firing'
local list_head while run_posix_cpu_timers() does list_for_each_safe.

Various bad things can happen, for example we can just delete this timer
so that list_for_each() will not notice it and run_posix_cpu_timers()
will not reset '->firing' flag. In that case,

	....

	if (timer->it.cpu.firing) {
		read_unlock(&tasklist_lock);
		timer->it.cpu.firing = -1;
		return TIMER_RETRY;
	}

sys_timer_settime() goes to 'retry:', calls posix_cpu_timer_set() again,
it returns TIMER_RETRY ...

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-24 08:13:14 -07:00
..
irq [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ() 2005-09-07 16:57:29 -07:00
power [PATCH] x86_64: Set up safe page tables during resume 2005-10-10 08:36:46 -07:00
acct.c [PATCH] kernel/acct: add kerneldoc 2005-09-10 10:06:26 -07:00
audit.c [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
auditsc.c [AUDIT] Allow filtering on system call success _or_ failure 2005-08-27 10:25:43 +01:00
capability.c [PATCH] kernel/capability.c: add kerneldoc 2005-07-27 16:26:06 -07:00
compat.c [PATCH] kernel: fix-up schedule_timeout() usage 2005-09-10 10:06:37 -07:00
configs.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cpu.c [PATCH] i386 CPU hotplug 2005-06-25 16:24:29 -07:00
cpuset.c [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
crash_dump.c [PATCH] kernel/crash_dump.c: add kerneldoc 2005-07-27 16:26:06 -07:00
dma.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
exec_domain.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
exit.c [PATCH] posix-timers: remove false BUG_ON() from run_posix_cpu_timers() 2005-10-24 08:12:35 -07:00
extable.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fork.c [PATCH] Threads shouldn't inherit PF_NOFREEZE 2005-10-19 23:04:31 -07:00
futex.c [PATCH] futex: remove duplicate code 2005-09-07 16:57:33 -07:00
intermodule.c [PATCH] introduce and use kzalloc 2005-09-07 16:57:45 -07:00
itimer.c [PATCH] itimer fixes 2005-07-27 16:25:51 -07:00
kallsyms.c [PATCH] ppc32: platform-specific functions missing from kallsyms. 2005-05-05 16:36:31 -07:00
Kconfig.hz [PATCH] i386: Selectable Frequency of the Timer Interrupt 2005-06-23 09:45:10 -07:00
Kconfig.preempt [PATCH] sched: voluntary kernel preemption 2005-06-25 16:24:45 -07:00
kexec.c [PATCH] kexec: fix sparse warnings 2005-06-28 14:53:40 -07:00
kfifo.c [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
kmod.c [PATCH] Keys: Pass session keyring to call_usermodehelper() 2005-06-24 00:05:18 -07:00
kprobes.c [PATCH] kprobes: fix bug when probed on task and isr functions 2005-09-07 16:58:01 -07:00
ksysfs.c [PATCH] Kdump: Export crash notes section address through sysfs 2005-06-25 16:24:51 -07:00
kthread.c [PATCH] use smp_mb/wmb/rmb where possible 2005-05-01 08:58:47 -07:00
Makefile [PATCH] spinlock consolidation 2005-09-10 10:06:21 -07:00
module.c [PATCH] use add_taint() for setting tainted bit flags 2005-09-13 08:22:29 -07:00
panic.c [PATCH] Call emergency_reboot from panic 2005-07-26 14:35:43 -07:00
params.c [PATCH] Ignore trailing whitespace on kernel parameters correctly 2005-09-28 07:46:41 -07:00
pid.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
posix-cpu-timers.c [PATCH] posix-timers: fix posix_cpu_timer_set() vs run_posix_cpu_timers() race 2005-10-24 08:13:14 -07:00
posix-timers.c [PATCH] Call exit_itimers from do_exit, not __exit_signal 2005-10-21 15:38:08 -07:00
printk.c [PATCH] Add printk_clock() 2005-09-21 10:11:54 -07:00
profile.c [PATCH] mostly_read data section 2005-07-07 18:23:46 -07:00
ptrace.c [PATCH] remove duplicated code from proc and ptrace 2005-09-07 16:57:43 -07:00
rcupdate.c [PATCH] rcu: keep rcu callback event counter 2005-10-17 15:27:58 -07:00
resource.c [PATCH] introduce and use kzalloc 2005-09-07 16:57:45 -07:00
sched.c [PATCH] Fix spinlock owner debugging 2005-09-13 09:59:04 -07:00
seccomp.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
signal.c [PATCH] Call exit_itimers from do_exit, not __exit_signal 2005-10-21 15:38:08 -07:00
softirq.c [PATCH] x86-64: Some cleanup and optimization to the processor data area. 2005-09-12 10:49:58 -07:00
softlockup.c [PATCH] detect soft lockups 2005-09-07 16:57:17 -07:00
spinlock.c [PATCH] spinlock consolidation 2005-09-10 10:06:21 -07:00
stop_machine.c [PATCH] smp_processor_id() cleanup 2005-06-21 18:46:13 -07:00
sys_ni.c [PATCH] remove sys_set_zone_reclaim() 2005-08-01 10:03:56 -07:00
sys.c [PATCH] reboot: comment and factor the main reboot functions 2005-09-22 22:17:33 -07:00
sysctl.c [NET]: Fix sparse warnings 2005-08-29 16:01:32 -07:00
time.c [PATCH] Add missing export of getnstimeofday() 2005-10-14 17:10:12 -07:00
timer.c [PATCH] schedule_timeout_[un]interruptible() speedup 2005-09-13 08:22:29 -07:00
uid16.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
user.c [PATCH] inotify 2005-07-12 20:38:38 -07:00
wait.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
workqueue.c [PATCH] introduce and use kzalloc 2005-09-07 16:57:45 -07:00