tree 4164272ddddfc2477005866ce3261c76470c0d1a
parent 3047817b894ddae62be07787bc8735a616104398
author Steffen Klassert <steffen.klassert@secunet.com> 1331274049 +0100
committer Herbert Xu <herbert@gondor.apana.org.au> 1331717156 +0800

padata: Fix race on sequence number wrap

When padata_do_parallel() is called from multiple cpus for the same
padata instance, we can get object reordering on sequence number wrap
because testing for sequence number wrap and reseting the sequence
number must happen atomically but is implemented with two atomic
operations. This patch fixes this by converting the sequence number
from atomic_t to an unsigned int and protect the access with a
spin_lock. As a side effect, we get rid of the sequence number wrap
handling because the seqence number wraps back to null now without
the need to do anything.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>