dm crypt: fix deadlock when async crypto algorithm returns -EBUSY (0618764c) · Commits · 戴 / test

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:

Ben Collins <ben.c@servergy.com> Signed-off-by:

Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org

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)

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