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Commit 0618764c authored by Ben Collins's avatar Ben Collins Committed by Mike Snitzer
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dm crypt: fix deadlock when async crypto algorithm returns -EBUSY 



I suspect this doesn't show up for most anyone because software
algorithms typically don't have a sense of being too busy.  However,
when working with the Freescale CAAM driver it will return -EBUSY on
occasion under heavy -- which resulted in dm-crypt deadlock.

After checking the logic in some other drivers, the scheme for
crypt_convert() and it's callback, kcryptd_async_done(), were not
correctly laid out to properly handle -EBUSY or -EINPROGRESS.

Fix this by using the completion for both -EBUSY and -EINPROGRESS.  Now
crypt_convert()'s use of completion is comparable to
af_alg_wait_for_completion().  Similarly, kcryptd_async_done() follows
the pattern used in af_alg_complete().

Before this fix dm-crypt would lockup within 1-2 minutes running with
the CAAM driver.  Fix was regression tested against software algorithms
on PPC32 and x86_64, and things seem perfectly happy there as well.

Signed-off-by: default avatarBen Collins <ben.c@servergy.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
parent 59779079

drivers/md/dm-crypt.c

+6 −6
Original line number Diff line number Diff line
@@ -925,11 +925,10 @@ static int crypt_convert(struct crypt_config *cc, 


		switch (r) {

		/* async */

		case -EINPROGRESS:

		case -EBUSY:

			wait_for_completion(&ctx->restart);

			reinit_completion(&ctx->restart);

			/* fall through*/

		case -EINPROGRESS:

			ctx->req = NULL;

			ctx->cc_sector++;

			continue;
@@ -1346,10 +1345,8 @@ static void kcryptd_async_done(struct crypto_async_request *async_req, 
	struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);

	struct crypt_config *cc = io->cc;



	if (error == -EINPROGRESS) {

		complete(&ctx->restart);

	if (error == -EINPROGRESS)

		return;

	}



	if (!error && cc->iv_gen_ops && cc->iv_gen_ops->post)

		error = cc->iv_gen_ops->post(cc, iv_of_dmreq(cc, dmreq), dmreq);
@@ -1360,12 +1357,15 @@ static void kcryptd_async_done(struct crypto_async_request *async_req, 
	crypt_free_req(cc, req_of_dmreq(cc, dmreq), io->base_bio);



	if (!atomic_dec_and_test(&ctx->cc_pending))

		return;

		goto done;



	if (bio_data_dir(io->base_bio) == READ)

		kcryptd_crypt_read_done(io);

	else

		kcryptd_crypt_write_io_submit(io, 1);

done:

	if (!completion_done(&ctx->restart))

		complete(&ctx->restart);

}



static void kcryptd_crypt(struct work_struct *work)