Re: [PATCH] kretprobe spinlock recursive remove

["bibo,mao" <bibo.mao@intel.com>]

Andrew Morton wrote:
> "bibo,mao" <bibo.mao@intel.com> wrote:
>> In recent linux kernel version, kretprobe in IA32 is implemented in 
>> kretprobe_trampoline. And break trap code is removed from 
>> retprobe_trampoline, instead trampoline_handler is called directly. 
>> Currently if kretprobe hander hit one trap which causes another 
>> kretprobe, there will be SPINLOCK recursive bug. This patch fixes this, 
>> and will skip trap during kretprobe handler execution. This patch is 
>> based on 2.6.16-rc6-mm2.
> 
> What is "recent linux kernel"?  2.6.16?  This patch does apply to 2.6.16 so
> I assume that's what you were referring to?
> 
> If you're referring to the kretprobes patches in -mm then which one
> introduced the problem?
Sorry, I did not clarify it out, it is againt 
kretprobe-kretprobe-booster.patch in -mm tree.

> 
> If you're referring to 2.6.16 then is this problem sufficiently serious to
> warrant inclusion of this patch in 2.6.16.1?
> 
> Please remember to include Signed-off-by: tags.
> 
>> --- arch/i386/kernel/kprobes.c.bak	2006-03-21 10:35:34.000000000 +0800
>> +++ arch/i386/kernel/kprobes.c	2006-03-21 10:37:44.000000000 +0800
> 
> Please prepare patches in `patch -p1' form.
> 
>> @@ -390,8 +390,11 @@ fastcall void *__kprobes trampoline_hand
>>   			/* another task is sharing our hash bucket */
>>                           continue;
>>
>> -		if (ri->rp && ri->rp->handler)
>> +		if (ri->rp && ri->rp->handler){
>> +			__get_cpu_var(current_kprobe) = &ri->rp->kp;
>>   			ri->rp->handler(ri, regs);
>> +			__get_cpu_var(current_kprobe) = NULL;
>> +		}
>>
>>   		orig_ret_address = (unsigned long)ri->ret_addr;
>>   		recycle_rp_inst(ri);
> 
> Your email client appears to be altering the patches in some manner.  It
> required `patch -l' to make this apply.
> 
> -
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