Doug / smarc-fsl-linux-kernel

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Commit f88fb981183e71daf40bbd84bc8251bbf7b59e19

Authored by Kiyoshi Ueda
Committed by Alasdair G Kergon
1 parent 03022c54b9
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

dm: dec_pending needs locking to save error value 

Multiple instances of dec_pending() can run concurrently so a lock is
needed when it saves the first error code.

I have never experienced actual problem without locking and just found
this during code inspection while implementing the barrier support
patch for request-based dm.

This patch adds the locking.
I've done compile, boot and basic I/O testings.

Cc: stable@kernel.org
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

Showing 1 changed file with 8 additions and 2 deletions Side-by-side Diff

... ... @@ -47,6 +47,7 @@
47 47 atomic_t io_count;
48 48 struct bio *bio;
49 49 unsigned long start_time;
  50 + spinlock_t endio_lock;
50 51 };
51 52  
52 53 /*
... ... @@ -578,8 +579,12 @@
578 579 struct mapped_device *md = io->md;
579 580  
580 581 /* Push-back supersedes any I/O errors */
581   - if (error && !(io->error > 0 && __noflush_suspending(md)))
582   - io->error = error;
  582 + if (unlikely(error)) {
  583 + spin_lock_irqsave(&io->endio_lock, flags);
  584 + if (!(io->error > 0 && __noflush_suspending(md)))
  585 + io->error = error;
  586 + spin_unlock_irqrestore(&io->endio_lock, flags);
  587 + }
583 588  
584 589 if (atomic_dec_and_test(&io->io_count)) {
585 590 if (io->error == DM_ENDIO_REQUEUE) {
... ... @@ -1226,6 +1231,7 @@
1226 1231 atomic_set(&ci.io->io_count, 1);
1227 1232 ci.io->bio = bio;
1228 1233 ci.io->md = md;
  1234 + spin_lock_init(&ci.io->endio_lock);
1229 1235 ci.sector = bio->bi_sector;
1230 1236 ci.sector_count = bio_sectors(bio);
1231 1237 if (unlikely(bio_empty_barrier(bio)))