When chainiv postpones requests it never calls their completion functions.
This causes symptoms such as memory leaks when IPsec is in use.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The previous patch to move chainiv and eseqiv into blkcipher created
a section mismatch for the chainiv exit function which was also called
from __init.  This patch removes the __exit marking on it.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

For compatibility with dm-crypt initramfs setups it is useful to merge
chainiv/seqiv into the crypto_blkcipher module.  Since they're required
by most algorithms anyway this is an acceptable trade-off.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This patch makes chainiv avoid spinning by postponing requests on lock
contention if the user allows the use of asynchronous algorithms.  If
a synchronous algorithm is requested then we behave as before.

This should improve IPsec performance on SMP when two CPUs attempt to
transmit over the same SA.  Currently one of them will spin doing nothing
waiting for the other CPU to finish its encryption.  This patch makes it
postpone the request and get on with other work.

If only one CPU is transmitting for a given SA, then we will process
the request synchronously as before.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The chain IV generator is the one we've been using in the IPsec stack.
It simply starts out with a random IV, then uses the last block of each
encrypted packet's cipher text as the IV for the next packet.

It can only be used by synchronous ciphers since we have to make sure
that we don't start the encryption of the next packet until the last
one has completed.

It does have the advantage of using very little CPU time since it doesn't
have to generate anything at all.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>