The only generic interface to execute asynchronously in the BH context is tasklet; however, it's marked deprecated and has some design flaws. To replace tasklets, BH workqueue support was recently added. A BH workqueue behaves similarly to regular workqueues except that the queued work items are executed in the BH context.
This patch converts dm-crypt from tasklet to BH workqueue. Like a regular workqueue, a BH workqueue allows freeing the currently executing work item. Converting from tasklet to BH workqueue removes the need for deferring bio_endio() again to a work item, which was buggy anyway. I tested this lightly with "--perf-no_read_workqueue --perf-no_write_workqueue" + some code modifications, but would really -appreciate if someone who knows the code base better could take a look. Signed-off-by: Tejun Heo <t...@kernel.org> Link: http://lkml.kernel.org/r/82b964f0-c2c8-a2c6-5b1f-f3145dc2c...@redhat.com Cc: Mikulas Patocka <mpato...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Alasdair Kergon <a...@redhat.com> Cc: Mike Snitzer <snit...@kernel.org> Cc: dm-devel@lists.linux.dev --- drivers/md/dm-crypt.c | 36 ++---------------------------------- 1 file changed, 2 insertions(+), 34 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 855b482cbff1..619c762d4072 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -73,11 +73,8 @@ struct dm_crypt_io { struct bio *base_bio; u8 *integrity_metadata; bool integrity_metadata_from_pool:1; - bool in_tasklet:1; struct work_struct work; - struct tasklet_struct tasklet; - struct convert_context ctx; atomic_t io_pending; @@ -1762,7 +1759,6 @@ static void crypt_io_init(struct dm_crypt_io *io, struct crypt_config *cc, io->ctx.r.req = NULL; io->integrity_metadata = NULL; io->integrity_metadata_from_pool = false; - io->in_tasklet = false; atomic_set(&io->io_pending, 0); } @@ -1771,13 +1767,6 @@ static void crypt_inc_pending(struct dm_crypt_io *io) atomic_inc(&io->io_pending); } -static void kcryptd_io_bio_endio(struct work_struct *work) -{ - struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); - - bio_endio(io->base_bio); -} - /* * One of the bios was finished. Check for completion of * the whole request and correctly clean up the buffer. @@ -1800,21 +1789,6 @@ static void crypt_dec_pending(struct dm_crypt_io *io) kfree(io->integrity_metadata); base_bio->bi_status = error; - - /* - * If we are running this function from our tasklet, - * we can't call bio_endio() here, because it will call - * clone_endio() from dm.c, which in turn will - * free the current struct dm_crypt_io structure with - * our tasklet. In this case we need to delay bio_endio() - * execution to after the tasklet is done and dequeued. - */ - if (io->in_tasklet) { - INIT_WORK(&io->work, kcryptd_io_bio_endio); - queue_work(cc->io_queue, &io->work); - return; - } - bio_endio(base_bio); } @@ -2246,11 +2220,6 @@ static void kcryptd_crypt(struct work_struct *work) kcryptd_crypt_write_convert(io); } -static void kcryptd_crypt_tasklet(unsigned long work) -{ - kcryptd_crypt((struct work_struct *)work); -} - static void kcryptd_queue_crypt(struct dm_crypt_io *io) { struct crypt_config *cc = io->cc; @@ -2263,9 +2232,8 @@ static void kcryptd_queue_crypt(struct dm_crypt_io *io) * it is being executed with irqs disabled. */ if (in_hardirq() || irqs_disabled()) { - io->in_tasklet = true; - tasklet_init(&io->tasklet, kcryptd_crypt_tasklet, (unsigned long)&io->work); - tasklet_schedule(&io->tasklet); + INIT_WORK(&io->work, kcryptd_crypt); + queue_work(system_bh_wq, &io->work); return; } -- 2.43.0
