[PATCH] futexes / now: duplicate lock of same type

[Chagin Dmitry]

On Fri, Feb 27, 2009 at 05:22:52PM +0100, Lucius Windschuh wrote:
> 2009/2/10 Chagin Dmitry <dchagin at freebsd.org>:
> >> > please, try http://lnxx64.googlecode.com/files/futexes_partial_II.patch
> >> > first patch fail at i386...
> 
> I am using your patch and Flash got a bit faster. :-)
> But witness reported this when I start my opera and load mail.google.com:
> 
> acquiring duplicate lock of same type: "futex lock"
>  1st futex lock @
> /usr/src/sys/modules/linux/../../compat/linux/linux_futex.c:179
>  2nd futex lock @
> /usr/src/sys/modules/linux/../../compat/linux/linux_futex.c:211
> KDB: stack backtrace:
> db_trace_self_wrapper(c09b535c,eb1d7b50,c06da5a5,4,c09b0871,...) at
> db_trace_self_wrapper+0x26
> kdb_backtrace(4,c09b0871,c0d62685,c6112d88,eb1d7bac,...) at kdb_backtrace+0x29
> _witness_debugger(c09b7f74,c0d626e7,c0d62685,d3,c09ab01b,...) at
> _witness_debugger+0x25
> witness_checkorder(c7526b80,9,c0d62685,d3,0,...) at witness_checkorder+0x469
> _sx_xlock(c7526b80,0,c0d62685,d3,0,...) at _sx_xlock+0x85
> futex_get0(0,0,102,c7526b80,0,...) at futex_get0+0x28c
> futex_get_op(eb1d7c44,eb1d7c58,c068ba4c,c770f088,4,...) at futex_get_op+0x93
> linux_sys_futex(c77336c0,eb1d7cf8,eb1d7d18,eb1d7d1c,c0d65b20,...) at
> linux_sys_futex+0x6a
> syscall(eb1d7d38) at syscall+0x283
> Xint0x80_syscall() at Xint0x80_syscall+0x20
> --- syscall (240, Linux ELF, linux_sys_futex), eip = 0x28cd69b3, esp =
> 0xbfbfde6c, ebp = 0x4000001 ---
> 
> Is this message potentially harmful?
> 
> More information can be gathered on request (e.g. textdump with a
> custom ddb script).
> 

hi, thanks for the concern!
this is expected behavior. this futexes design problem.

anyway thnx!
-- 
Have fun!
chd