Re: Deadlock on the mm->mmap_sem

Andrea Arcangeli
2001-09-19T18:45:43Z

On Wed, Sep 19, 2001 at 02:16:56PM -0400, Benjamin LaHaise wrote:
> I don't know about you, but I'm mildly concerned that copyright attributions
> vanished.

can you be more precise? which copyright attribution? my rwsem are
written totally from scratch, they doesn't share anything with the
previous code, it is just a code replacement. As far I can tell deleted
some file, and with it also its headers but that seems not to infinge
any copyright, I didn't removed only the copyright attribution. If I
removed only the copyright attribution please let me know of course,
that would been a silly mistake.

To be pedantic the only idea I shared with the old code (but that's just
the idea, not the implementation, so AFIK only a patent on such idea
could protect it from its free usage usage) is to return the rwsem again
from rwsem_wake and friends to avoid saving it in the asm slow path, and
I written that:

/*
* We return the semaphore itself from the C functions so we can pass it
* in %eax via regparm and we don't need to declare %eax clobbered by C.
* This is mostly for x86 but maybe other archs can make a use of it
* too.
* Idea is from David Howells <dhowells@redhat.com>.
*/

And the xadd version is scheduled for removal anyways soon btw (David
just dropped it in its implementation).

Andrea