• Peter Zijlstra's avatar
    block: Use u64_stats_init() to initialize seqcounts · 90d3839b
    Peter Zijlstra authored
    
    
    Now that seqcounts are lockdep enabled objects, we need to explicitly
    initialize runtime allocated seqcounts so that lockdep can track them.
    
    Without this patch, Fengguang was seeing:
    
      [    4.127282] INFO: trying to register non-static key.
      [    4.128027] the code is fine but needs lockdep annotation.
      [    4.128027] turning off the locking correctness validator.
      [    4.128027] CPU: 0 PID: 96 Comm: kworker/u4:1 Not tainted 3.12.0-next-20131108-10601-gbad570d #2
      [    4.128027] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
      [    ...     ]
      [    4.128027] Call Trace:
      [    4.128027]  [<7908e744>] ? console_unlock+0x353/0x380
      [    4.128027]  [<79dc7cf2>] dump_stack+0x48/0x60
      [    4.128027]  [<7908953e>] __lock_acquire.isra.26+0x7e3/0xceb
      [    4.128027]  [<7908a1c5>] lock_acquire+0x71/0x9a
      [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
      [    4.128027]  [<7940658b>] throtl_update_dispatch_stats+0x7c/0x153
      [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
      [    4.128027]  [<794079aa>] blk_throtl_bio+0x1c3/0x485
      ...
    
    Use u64_stats_init() for all affected data structures, which initializes
    the seqcount.
    Reported-and-Tested-by: default avatarFengguang Wu <fengguang.wu@intel.com>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
    [ Folded in another fix from the mailing list as well as a fix to that fix. Tweaked commit message. ]
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/1384314134-6895-1-git-send-email-john.stultz@linaro.org
    
    
    [ So I actually think that the two SOBs from PeterZ are the right depiction of the patch route. ]
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    90d3839b