[fprint] Strange Crash in __pthread_mutex_unlock_usercnt

[Keaton Mowery]

Updating to libusbx seems to have solved the problem. If it crops up
again, I'll send more detailed debugging logs. Thanks, Bastien!

Keaton

On Thu, Oct 4, 2012 at 5:16 AM, Bastien Nocera <hadess at hadess.net> wrote:
> Hey,
>
> On Wed, 2012-10-03 at 16:01 -0700, Keaton Mowery wrote:
>> Hi all,
>>
>> I'm seeing a very odd crash while using libfprint's async API. Here's
>> a backtrace:
>>
>> ---------
>> Program received signal SIGSEGV, Segmentation fault.
>> 0xb4e14211 in __pthread_mutex_unlock_usercnt () from
>> /lib/i686/cmov/libpthread.so.0
>> (gdb) bt
>> #0  0xb4e14211 in __pthread_mutex_unlock_usercnt () from
>> /lib/i686/cmov/libpthread.so.0
>> #1  0xb4efd016 in pthread_mutex_unlock () from /lib/i686/cmov/libc.so.6
>> #2  0xb4e04f0e in ?? () from /lib/libusb-1.0.so.0
>> #3  0xb4e02e65 in ?? () from /lib/libusb-1.0.so.0
>> #4  0xb4e03641 in libusb_handle_events_timeout () from /lib/libusb-1.0.so.0
>> #5  0xb5137a7f in fp_handle_events_timeout (timeout=0xbffff5e4) at poll.c:231
>> #6  0x08052800 in main (argc=1, argv=0xbffff6d4) at fpserv.cpp:27
>> ---------
>>
>> Something also sometimes dumps to dmesg:
>> [   54.740378] fpserv[1714]: segfault at 9f2ac60 ip b453d211 sp
>> bfee078c error 4 in libpthread-2.11.2.so[b4534000+15000]
>>
>> We have a microsoft fingerprint reader, and have 156 enrolled fingerprints.
>>
>> Any thoughts?
>
> You should install the debug info, and then check with newer versions of
> libusb (such as libusbx) or run your program under valgrind.
>
> It's very likely you're doing something wrong in your program if the
> problem occurs every time, seeing as that same model of hardware works
> for others (including myself) using fprintd.
>
> Cheers
>