Re: [PATCH] fs/locks.c: Fix posix locking for threaded tasks

[Matthew Wilcox]

On Mon, Jun 10, 2002 at 01:41:19PM +0100, Matthew Wilcox wrote:
> On Mon, Jun 10, 2002 at 12:41:20AM -0600, Andreas Dilger wrote:
> > Otherwise, this change makes it impossible to write a multi-threaded
> > program that _does_ allow you use locking between threads.  If anything,
> > this PID check could be conditional on some extra lock flag (e.g.
> > THREADS_SHARE_LOCKS or whatever).
> 
> if you're locking between threads, you should be using posix thread
> mutexes, not file locks, IMO.  There's nothing in SUS v3 which says
> you can do what you've described.

the light dawned... of course it doesn't say.  If you have userlevel
threads (or some M:N system), either you force the threading library
to reimplement the fcntl lock interface, or they have to share locks.
I can't imagine that even the posix threading people require a
reimplementation of the grotesque solaris file locking scheme in
userspace.

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