[v3,0/3] blk-mq: Fix a race between iterating over requests and freeing requests

Message

Bart Van Assche March 26, 2021, 2:29 a.m. UTC

Hi Jens,

This patch series fixes the race between iterating over requests and
freeing requests that has been reported by multiple different users over
the past two years. Please consider this patch series for kernel v5.13.

Thank you,

Bart.

Changes compared to v2:
- Converted the single v2 patch into a series of three patches.
- Switched from SRCU to a combination of RCU and semaphores.

Changes compared to v1:
- Reformatted patch description.
- Added Tested-by/Reviewed-by tags.
- Changed srcu_barrier() calls into synchronize_srcu() calls.

Bart Van Assche (3):
  blk-mq: Move the elevator_exit() definition
  blk-mq: Introduce atomic variants of the tag iteration functions
  blk-mq: Fix races between iterating over requests and freeing requests

 block/blk-core.c          | 34 ++++++++++++++-
 block/blk-mq-tag.c        | 87 ++++++++++++++++++++++++++++++++++-----
 block/blk-mq-tag.h        |  8 ++--
 block/blk-mq.c            | 31 ++++++++++----
 block/blk-mq.h            |  1 +
 block/blk.h               | 11 +----
 block/elevator.c          |  9 ++++
 drivers/scsi/hosts.c      | 16 +++----
 drivers/scsi/ufs/ufshcd.c |  4 +-
 include/linux/blk-mq.h    |  2 +
 10 files changed, 160 insertions(+), 43 deletions(-)