1. 27 May, 2020 21 commits
  2. 26 May, 2020 1 commit
    • Jiri Kosina's avatar
      block/floppy: fix contended case in floppy_queue_rq() · 263c6158
      Jiri Kosina authored
      Since the switch of floppy driver to blk-mq, the contended (fdc_busy) case
      in floppy_queue_rq() is not handled correctly.
      
      In case we reach floppy_queue_rq() with fdc_busy set (i.e. with the floppy
      locked due to another request still being in-flight), we put the request
      on the list of requests and return BLK_STS_OK to the block core, without
      actually scheduling delayed work / doing further processing of the
      request. This means that processing of this request is postponed until
      another request comes and passess uncontended.
      
      Which in some cases might actually never happen and we keep waiting
      indefinitely. The simple testcase is
      
      	for i in `seq 1 2000`; do echo -en $i '\r'; blkid --info /dev/fd0 2> /dev/null; done
      
      run in quemu. That reliably causes blkid eventually indefinitely hanging
      in __floppy_read_block_0() waiting for completion, as the BIO callback
      never happens, and no further IO is ever submitted on the (non-existent)
      floppy device. This was observed reliably on qemu-emulated device.
      
      Fix that by not queuing the request in the contended case, and return
      BLK_STS_RESOURCE instead, so that blk core handles the request
      rescheduling and let it pass properly non-contended later.
      
      Fixes: a9f38e1d ("floppy: convert to blk-mq")
      Cc: stable@vger.kernel.org
      Tested-by: default avatarLibor Pechacek <lpechacek@suse.cz>
      Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      263c6158
  3. 24 May, 2020 1 commit
  4. 21 May, 2020 14 commits
  5. 16 May, 2020 1 commit
  6. 13 May, 2020 2 commits
    • Jens Axboe's avatar
      Merge branch 'md-next' of... · 8fd2b980
      Jens Axboe authored
      Merge branch 'md-next' of git://git.kernel.org/pub/scm/linux/kernel/git/song/md into for-5.8/drivers
      
      Pull MD changes from Song.
      
      * 'md-next' of git://git.kernel.org/pub/scm/linux/kernel/git/song/md:
        md/raid1: Replace zero-length array with flexible-array
        md: add a newline when printing parameter 'start_ro' by sysfs
        md: stop using ->queuedata
        md/raid1: release pending accounting for an I/O only after write-behind is also finished
        md: remove redundant memalloc scope API usage
        raid5: update code comment of scribble_alloc()
        raid5: remove gfp flags from scribble_alloc()
        md: use memalloc scope APIs in mddev_suspend()/mddev_resume()
        md: remove the extra line for ->hot_add_disk
        md: flush md_rdev_misc_wq for HOT_ADD_DISK case
        md: don't flush workqueue unconditionally in md_open
        md: add new workqueue for delete rdev
        md: add checkings before flush md_misc_wq
      8fd2b980
    • Gustavo A. R. Silva's avatar
      md/raid1: Replace zero-length array with flexible-array · 358369f0
      Gustavo A. R. Silva authored
      The current codebase makes use of the zero-length array language
      extension to the C90 standard, but the preferred mechanism to declare
      variable-length types such as these ones is a flexible array member[1][2],
      introduced in C99:
      
      struct foo {
              int stuff;
              struct boo array[];
      };
      
      By making use of the mechanism above, we will get a compiler warning
      in case the flexible array does not occur last in the structure, which
      will help us prevent some kind of undefined behavior bugs from being
      inadvertently introduced[3] to the codebase from now on.
      
      Also, notice that, dynamic memory allocations won't be affected by
      this change:
      
      "Flexible array members have incomplete type, and so the sizeof operator
      may not be applied. As a quirk of the original implementation of
      zero-length arrays, sizeof evaluates to zero."[1]
      
      sizeof(flexible-array-member) triggers a warning because flexible array
      members have incomplete type[1]. There are some instances of code in
      which the sizeof operator is being incorrectly/erroneously applied to
      zero-length arrays and the result is zero. Such instances may be hiding
      some bugs. So, this work (flexible-array member conversions) will also
      help to get completely rid of those sorts of issues.
      
      This issue was found with the help of Coccinelle.
      
      [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
      [2] https://github.com/KSPP/linux/issues/21
      [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
      Signed-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      358369f0