Messages in this thread Patch in this message | | | Date | Tue, 27 May 2008 11:31:43 +0800 | From | "Luming Yu" <> | Subject | Re: [RFC PATCH] set TASK_TRACED before arch_ptrace code to fix a race |
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> > if happens, it should be a bug, right?
It does happen!!
Call Trace: [<a000000100011bd0>] show_stack+0x50/0xa0 sp=e000000146bbfbb0 bsp=e000000146bb0e08 [<a000000100011c50>] dump_stack+0x30/0x60 sp=e000000146bbfd80 bsp=e000000146bb0de8 [<a0000001000979a0>] get_signal_to_deliver+0x60/0x6e0 sp=e000000146bbfd80 bsp=e000000146bb0d80 [<a0000001000343d0>] ia64_do_signal+0xb0/0xd00 sp=e000000146bbfd80 bsp=e000000146bb0cd8 [<a000000100012650>] do_notify_resume_user+0xf0/0x140 sp=e000000146bbfe20 bsp=e000000146bb0ca8 [<a00000010000aac0>] notify_resume_user+0x40/0x60 sp=e000000146bbfe20 bsp=e000000146bb0c58 [<a00000010000a9f0>] skip_rbs_switch+0xe0/0x110 sp=e000000146bbfe30 bsp=e000000146bb0c58 [<a000000000010740>] __kernel_syscall_via_break+0x0/0x20 sp=e000000146bc0000 bsp=e000000146bb0c58
>> > I will try to customize kernel to capture call trace for a precise code path.
I applied the following patch , and got the call trace above.. If apply my RFC patch as antidote, I don't see "deliver" ... Is the problem clear now? I will serve you until every thing is clear to you.
Thanks, Luming
Signed-off-by: Yu Luming <luming.yu@intel.com>
diff -Bru 1/kernel/signal.c 0/kernel/signal.c --- 1/kernel/signal.c 2008-05-27 15:18:48.000000000 +0800 +++ 0/kernel/signal.c 2008-05-27 15:08:51.000000000 +0800 @@ -38,6 +38,7 @@ */
static struct kmem_cache *sigqueue_cachep; +unsigned long global_arch_ptrace_stop_flag =0;
static int __sig_ignored(struct task_struct *t, int sig) { @@ -1501,9 +1502,12 @@ * siglock. That must prevent us from sleeping in TASK_TRACED. * So after regaining the lock, we must check for SIGKILL. */ + global_arch_ptrace_stop_flag = 1; spin_unlock_irq(¤t->sighand->siglock); arch_ptrace_stop(exit_code, info); + spin_lock_irq(¤t->sighand->siglock); + global_arch_ptrace_stop_flag = 0; killed = sigkill_pending(current); }
@@ -1701,6 +1705,8 @@ struct signal_struct *signal = current->signal; int signr;
+ if (global_arch_ptrace_stop_flag) + dump_stack(); relock: /* * We'll jump back here after any time we were stopped in TASK_STOPPED.
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