Re: [Qemu-devel] [PATCH v3 03/15] exec-all.h: revert tb_page_addr_t to target_ulong

[Alex Bennée]

Emilio G. Cota <address@hidden> writes:

> On Mon, Oct 03, 2016 at 10:32:55 +0100, Alex Bennée wrote:
> (snip)
>> However the series as a whole does have value. As you can see from the
>> other patches there are some real races being picked up by the sanitizer
>> which only really become visible when a) you remove the noise of the
>> "false" positives and b) run the test many many times. For example this
>> one:
>>
>> ==================
>> WARNING: ThreadSanitizer: data race (pid=24906)
>>   Read of size 8 at 0x7db4000261f0 by thread T3 (mutexes: write M8203):
>>     #0 do_tb_flush /home/alex/lsrc/qemu/qemu.git/translate-all.c:872 
>> (qemu-arm+0x00006000ce68)
>>     #1 process_queued_cpu_work 
>> /home/alex/lsrc/qemu/qemu.git/cpus-common.c:337 (qemu-arm+0x000060116712)
>>     #2 cpu_loop /home/alex/lsrc/qemu/qemu.git/linux-user/main.c:654 
>> (qemu-arm+0x000060052213)
>>     #3 clone_func /home/alex/lsrc/qemu/qemu.git/linux-user/syscall.c:6070 
>> (qemu-arm+0x0000600686fb)
>>     #4 <null> <null> (libtsan.so.0+0x0000000230d9)
>>
>>   Previous write of size 8 at 0x7db4000261f0 by main thread (mutexes: write 
>> M8):
>>     #0 cpu_list_add /home/alex/lsrc/qemu/qemu.git/cpus-common.c:87 
>> (qemu-arm+0x000060115b7a)
>>     #1 cpu_exec_init /home/alex/lsrc/qemu/qemu.git/exec.c:641 
>> (qemu-arm+0x000060009900)
>>     #2 arm_cpu_initfn /home/alex/lsrc/qemu/qemu.git/target-arm/cpu.c:447 
>> (qemu-arm+0x0000600f833b)
> [..]
>
> Nice! Which patch fixes this--patch 10? It would be cool to have this
> report in the corresponding commit message.

This particular one only actually showed up after I sent the last
series - I'd kicked off 1000 repeating tests just before I boarded my
flight back home :-)

However patch 10 fixes another rare case which is in the class of races
caused by creating or destroying a thread just as we flush.

>
> Thanks,
>
>               Emilio


--
Alex Bennée