tree 75a66020271291432bf06bc7db7af66a37de5c9a
parent 9460dee4b2258e3990906fb34099481c8334c267
author Stefan Hajnoczi <stefanha@redhat.com> 1417519394 +0000
committer Paolo Bonzini <pbonzini@redhat.com> 1433517000 +0200

bitmap: add atomic set functions

Use atomic_or() for atomic bitmaps where several threads may set bits at
the same time.  This avoids the race condition between threads loading
an element, bitwise ORing, and then storing the element.

When setting all bits in a word we can avoid atomic ops and instead just
use an smp_mb() at the end.

Most bitmap users don't need atomicity so introduce new functions.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <1417519399-3166-2-git-send-email-stefanha@redhat.com>
[Avoid barrier in the single word case, use full barrier instead of write.
 - Paolo]
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>