Re: Semaphore

[Rajath N R <rajathnr@xxxxxxxxx>]

Hi,
    I think santosh is talking about user land IPC (semget). thread/process which has acquired a sema lock/sem down using semop(2) syscall. 



Thanks,
Rajath

On Fri, Feb 24, 2012 at 3:54 PM, Kristof Provost <kristof@xxxxxxxxxx> wrote:

On 2012-02-24 12:15:03 (+0200), Kosta Zertsekel <zertsekel@xxxxxxxxx> wrote:
> I think of user land program opening a socket and crashing on
> segmentation fault.
> In code 'socket' syscall does:
>     sock_map_fd --> sock_alloc_file --> alloc_file --> ... get lost ...
> Where exactly in this case lock is held - I mean the lock that gets
> released when user land process dies?

In this case there doesn't appear to be any lock. The sock_map_fd
function is most probably called from the socket syscall. This call
isn't locked. Multiple processes can be in the socket syscall at the
same time.
There certainly won't be a (kernel) lock which is held between two system
calls.

Regards,
Kristof

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-- 
Thanks & Regards,
Rajath N R
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