Re: [Valgrind-users] SfMayBlock with fuse-compatible

[Radoslaw K. <ku...@9l...>]

Hi Ivo,

here is the log that appeared when we switched on trace-syscalls:

SYSCALL[28094,1](12) sys_brk ( 0x0 ) --> [pre-success] Success(0x4000000)
--28094-- REDIR: 0x37458176d0 (ld-linux-x86-64.so.2:strlen) redirected 
to 0x380550c1 (vgPlain_amd64_linux_REDIR_FOR_strlen)
SYSCALL[28094,1](63) sys_newuname ( 0xffefffb10 )[sync] --> Success(0x0)
--28094-- REDIR: 0x37458174e0 (ld-linux-x86-64.so.2:index) redirected to 
0x380550db (vgPlain_amd64_linux_REDIR_FOR_index)
SYSCALL[28094,1](89) sys_readlink ( 0x374581b667(/proc/self/exe), 
0xffeffec10, 4096 ) --> [pre-success] Success(0x52)
valgrind: m_syswrap/syswrap-main.c:1938 (vgPlain_client_syscall): 
Assertion '0 == (sci->flags & ~(SfPollAfter | SfYieldAfter | 
SfNoWriteResult))' failed.


We also managed to create simple file exposing the problem (see attachment).

Exact command used by us to reproduce the problem:
valgrind --tool=memcheck -v --trace-syscalls=yes 
--sim-hints=fuse-compatible ./a.out

Radek


W dniu 06.12.2016 o 17:23, Ivo Raisr pisze:
>
>
> 2016-12-06 15:39 GMT+00:00 Radoslaw Kujawa <ku...@9l... 
> <mailto:ku...@9l...>>:
>
>     Hi everyone,
>
>     we're trying to run valgrind on a multi-threaded binary that uses fuse to emulate a filesystem. We've found|--sim-hints=|fuse-compatible flag, which is great (resolves some problems with deadlocks), but then valgrind fails on an assert:
>
>     vg_assert(0 == (sci->flags & ~(SfPollAfter | SfYieldAfter | SfNoWriteResult))); (in syswrap_main.c)
>
>     In our case (sci->flags & SfMayBlock) is true. When we added SfMayBlock to acceptable flags, and recompiled valgrind, everything worked fine.
>
>     Do you have and idea what we can do to run our binary in a simple way (without any hacks in assertions...)? Is it some configuration issue to allow blocking operations or maybe it is a bug in valgrind itself?
>
>
> Can you isolate this problem in a very simple program so there is a 
> reproducible test case?
> Alternatively, please provide output of running Valgrind with 
> '--trace-syscalls=yes'.
> I.