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

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Message-ID: <f074f848-5a26-473b-ae98-1932e9a8cbd1@redhat.com>
Date: Mon, 28 Oct 2024 19:00:40 -0400
From: Matthew Sakai <msakai@...hat.com>
To: Dan Carpenter <dan.carpenter@...aro.org>, oe-kbuild@...ts.linux.dev,
 Mike Snitzer <snitzer@...nel.org>
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: drivers/md/dm-vdo/data-vio.c:976 vdo_launch_bio() warn:
 inconsistent returns '&pool->lock'.

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?

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@...el.com>
> | Reported-by: Dan Carpenter <dan.carpenter@...aro.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
>