crypto: qat - add backlog mechanism
The implementations of the crypto algorithms (aead, skcipher, etc) in
the QAT driver do not properly support requests with the
CRYPTO_TFM_REQ_MAY_BACKLOG flag set. If the HW queue is full, the driver
returns -EBUSY but does not enqueue the request. This can result in
applications like dm-crypt waiting indefinitely for the completion of a
request that was never submitted to the hardware.
Fix this by adding a software backlog queue: if the ring buffer is more
than eighty percent full, then the request is enqueued to a backlog
list and the error code -EBUSY is returned back to the caller.
Requests in the backlog queue are resubmitted at a later time, in the
context of the callback of a previously submitted request.
The request for which -EBUSY is returned is then marked as -EINPROGRESS
once submitted to the HW queues.
The submission loop inside the function qat_alg_send_message() has been
modified to decide which submission policy to use based on the request
flags. If the request does not have the CRYPTO_TFM_REQ_MAY_BACKLOG set,
the previous behaviour has been preserved.
Based on a patch by
Vishnu Das Ramachandran <firstname.lastname@example.org>
Fixes: d370cec32194 ("crypto: qat - Intel(R) QAT crypto interface")
Reported-by: Mikulas Patocka <email@example.com>
Reported-by: Kyle Sanderson <firstname.lastname@example.org>
Signed-off-by: Giovanni Cabiddu <email@example.com>
Reviewed-by: Marco Chiappero <firstname.lastname@example.org>
Signed-off-by: Herbert Xu <email@example.com>
9 files changed