From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: [PATCH v2] dm crypt: fix deadlock when algo returns -EBUSY Date: Tue, 7 Apr 2015 12:28:42 -0400 Message-ID: <20150407162842.GA54137@redhat.com> References: <1428077387-2292-1-git-send-email-ben.c@servergy.com> <20150407155501.GA29040@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20150407155501.GA29040@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Ben Collins Cc: dm-devel@redhat.com, Mikulas Patocka , Milan Broz , Alasdair Kergon List-Id: dm-devel.ids On Tue, Apr 07 2015 at 11:55P -0400, Mike Snitzer wrote: > It looks like you're _always_ using the completion regardless of whether > crypt_convert() will be waiting (e.g. even if error is 0). > > I can see this "working" but it seems less than ideal. Would it be > better to record the need to use the completion in ctx and then > conditionally call complete()? Actually, how about using !completion_done() before calling complete()? If you think this would be OK, any chance you could re-test with this? From: Ben Collins Date: Fri, 3 Apr 2015 16:09:46 +0000 Subject: [PATCH] dm crypt: fix deadlock when algo 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. 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 Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org --- drivers/md/dm-crypt.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index ea09d54..cab96ca 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -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) -- 1.9.5 (Apple Git-50.3)