lkml.org 
[lkml]   [2002]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Linux-ia64] reader-writer livelock problem
In message <1036777105.13021.13.camel@ixodes.goop.org> you write:
>> Even without interrupts that would be a bug. It isn't ever safe to
>> attempt to retake a read lock if you already hold it, because you may
>> deadlock with a pending writer. Fair multi-reader locks aren't
>> recursive locks.

On Sat, Nov 09, 2002 at 01:48:17PM +1100, Rusty Russell wrote:
> That's the point. This is explicitly guaranteed with the current
> locks, and you are allowed to recurse on them. The netfilter code
> explicitly uses this to retake the net brlock, since it gets called
> from different paths.
> Implement "read_lock_yield" or "wrlock_t" but don't break existing
> semantics until 2.7 *please*!

My only interest is doing this specifically for problematic cases,
e.g. the tasklist_lock. Other usages probably shouldn't be altered
during this release cycle unless they too prove problematic, in which
case their usages should be fixed by their maintainers as bugfixes.

Of course, I'm not happy to hear about this explicit recursion.


Bill
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:30    [W:0.048 / U:0.392 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site