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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: Ben Collins <ben.c@servergy.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Ben Collins 2015-04-03 16:09:46 +00:00 committed by Mike Snitzer
parent 5977907937
commit 0618764cb2
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/md/dm-crypt.c
View File

@ -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)