[sr-dev] shm_regex deadlock

[Stefan Keller]

Hi,

I used the shm_regex functions from lib in one of my own modules and
noticed that it is dead-locking (it hangs in FUTEX_WAIT).
The code hangs in regexec() when trying to acquire the lock. This was
a bit hard to find out as I couldn't reproduce it in a virtual
machine with some test code I wrote. It turns out this only happens if
the machine has more than one physical CPU core.
Reproducable on x86_64 with two CPU cores, glibc 2.3.6 (from Debian
Etch) and glibc 2.11.1 (from Ubuntu Jaunty).
Attached is a patch which does its own locking and thus works around
this problem.

Best regards,
Stefan

-- 
M.Eng. Stefan Keller
CTO (Technischer Leiter)

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