Re: drivers/md/dm-vdo/data-vio.c:976 vdo_launch_bio() warn: inconsistent returns '&pool->lock'.

[Philip Li <philip.li@intel.com>]

On Tue, Oct 29, 2024 at 11:03:07AM +0800, Philip Li wrote:
> On Mon, Oct 28, 2024 at 07:00:40PM -0400, Matthew Sakai wrote:
> > This should be addressed upstream by commit
> > 872564c501b72ae0c84af51084753e8652e4a84b ("dm vdo data-vio: silence sparse
> > warnings about locking context imbalances")
> > 
> > That commit is from February. Would it be possible for these checks to use a
> > more up-to-date version of the code before warning us about things that have
> > already been addressed?
> 
> Sorry about this Matt, the bot side will check why this happens and fix
> the issue asap to avoid meaningless report.

Hi Matt and Dan, would you mind do a further check of this, per the re-test,
smatch warns as below on v6.12-rc3

	drivers/md/dm-vdo/data-vio.c:982 vdo_launch_bio() warn: inconsistent returns '&pool->lock'.
	  Locked on  : 972,977
	  Unlocked on: 982

The corresponding code of drivers/md/dm-vdo/data-vio.c is below

 942 static void wait_permit(struct limiter *limiter, struct bio *bio)
 943         __releases(&limiter->pool->lock)
 944 {
 945         DEFINE_WAIT(wait);
 946
 947         bio_list_add(&limiter->new_waiters, bio);
 948         prepare_to_wait_exclusive(&limiter->blocked_threads, &wait,
 949                                   TASK_UNINTERRUPTIBLE);
 950         spin_unlock(&limiter->pool->lock);
 951         io_schedule();
 952         finish_wait(&limiter->blocked_threads, &wait);
 953 }
 954
 955 /**
 956  * vdo_launch_bio() - Acquire a data_vio from the pool, assign the bio to it, and launch it.
 957  *
 958  * This will block if data_vios or discard permits are not available.
 959  */
 960 void vdo_launch_bio(struct data_vio_pool *pool, struct bio *bio)
 961 {
 962         struct data_vio *data_vio;
 963
 964         VDO_ASSERT_LOG_ONLY(!vdo_is_state_quiescent(&pool->state),
 965                             "data_vio_pool not quiescent on acquire");
 966
 967         bio->bi_private = (void *) jiffies;
 968         spin_lock(&pool->lock);
 969         if ((bio_op(bio) == REQ_OP_DISCARD) &&
 970             !acquire_permit(&pool->discard_limiter)) {
 971                 wait_permit(&pool->discard_limiter, bio);
 972                 return;
 973         }
 974
 975         if (!acquire_permit(&pool->limiter)) {
 976                 wait_permit(&pool->limiter, bio);
 977                 return;
 978         }
 979
 980         data_vio = get_available_data_vio(pool);
 981         spin_unlock(&pool->lock);
 982         launch_bio(pool->completion.vdo, data_vio, bio);
 983 }

Thanks

> 
> > 
> > Matt
> > 
> > On 10/21/24 3:19 AM, Dan Carpenter wrote:
> > > Hi Mike,
> > > 
> > > First bad commit (maybe != root cause):
> > > 
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head:   3d5ad2d4eca337e80f38df77de89614aa5aaceb9
> > > commit: f36b1d3ba533d21b5b793623f05761b0297d114e dm vdo: use a proper Makefile for dm-vdo
> > > config: x86_64-randconfig-161-20241019 (https://download.01.org/0day-ci/archive/20241019/202410191209.osrd8z9H-lkp@intel.com/config)
> > > compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
> > > 
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> > > | Closes: https://lore.kernel.org/r/202410191209.osrd8z9H-lkp@intel.com/
> > > 
> > > smatch warnings:
> > > drivers/md/dm-vdo/data-vio.c:976 vdo_launch_bio() warn: inconsistent returns '&pool->lock'.
> > > 
> > > vim +976 drivers/md/dm-vdo/data-vio.c
> > > 
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  958  void vdo_launch_bio(struct data_vio_pool *pool, struct bio *bio)
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  959  {
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  960  	struct data_vio *data_vio;
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  961
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  962  	ASSERT_LOG_ONLY(!vdo_is_state_quiescent(&pool->state),
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  963  			"data_vio_pool not quiescent on acquire");
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  964
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  965  	bio->bi_private = (void *) jiffies;
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  966  	spin_lock(&pool->lock);
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  967  	if ((bio_op(bio) == REQ_OP_DISCARD) &&
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  968  	    !acquire_permit(&pool->discard_limiter, bio))
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  969  		return;
> > >                                                          ^^^^^^
> > > 
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  970
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  971  	if (!acquire_permit(&pool->limiter, bio))
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  972  		return;
> > >                                                          ^^^^^^
> > > Still holding pool->lock on these paths.
> > > 
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  973
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  974  	data_vio = get_available_data_vio(pool);
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  975  	spin_unlock(&pool->lock);
> > > 79535a7881c0cb Matthew Sakai 2023-11-16 @976  	launch_bio(pool->completion.vdo, data_vio, bio);
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  977  }
> > > 79535a7881c0cb Matthew Sakai 2023-11-16  978
> > > 
> > 
> >