[lkml]   [2007]   [May]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch 14/22] pollfs: pollable futex
On 5/2/07, Davi Arnaut <> wrote:
> It's quite easy to implement this scheme by write()ing the futexes all
> at once but that would break the one futex per fd association. For
> atomicity: if one of the futexes can't be queued, we would rollback
> (unqueue) the others.
> Sounds sane?

I don't know how you use "unqueue" in this context. If a queued futex
is one which is /locked/ by te call, then yes, this is the semantics
needed. Atomically locking a number of futexes means that if one of
the set cannot be locked all operations done to lock the others have
to be undone. It's an all-or-nothing situation.

Locking is not as easy as you might think, though. For non-PI futexes
there is deliberately no protocol in place describing what "locked"
means. The locking operation has to be customizable. This is what
the FUTEX_OP_* stuff is about.

And you wrote that currently each futex needs its own file descriptor.
So this would have to be changed, too.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-05-02 18:49    [W:0.109 / U:35.352 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site