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

From: Matthew Wilcox (
Date: Wed Jun 12 2002 - 17:33:06 EST

On Wed, Jun 12, 2002 at 05:18:56PM -0500, Saurabh Desai wrote:
> Yes, it's needed for M:N threading library. Here is scenario: Task A
> holds a lock and waiting for some event in library, now task B tries
> to acquire that lock and waits in kernel and this can create a deadlock.
> These tasks are created with CLONE_THREAD (for M:N) flag.
> This change (removing pid check) may cause problem for 1:1 (linuxthreads),
> where each task has unique pid and tgid. Again, whether that's a right
> behavior or not is questionable.
> However, with CLONE_THREAD flag, all tasks shares "tgid" value with unique
> pid and that's why I suggested earlier to change the "fl_pid" from "pid"
> to "tgid" and it works for both the cases (M:N and 1:1).

But then we have different behaviour for applications which are linked
against a 1:1 library and an M:N library. That makes no sense.

Revolutions do not require corporate support.
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