fs/inode.c:1924:45-46: WARNING: atomic_add_unless

BCC: [email protected]
CC: [email protected]
CC: [email protected]
TO: Josef Bacik <[email protected]>
CC: Christian Brauner <[email protected]>
CC: Mateusz Guzik <[email protected]>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   94515f3a7d4256a5062176b7d6ed0471938cd51a
commit: 9e70e985bdc2c6fe7a160e4d59ddd7c0a39bc077 fs: rework iput logic
date:   11 months ago
:::::: branch date: 2 days ago
:::::: commit date: 11 months ago
config: powerpc64-randconfig-r064-20260716 (https://download.01.org/0day-ci/archive/20260719/[email protected]/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project b3e6e6dabdc02153552a64fc74ff5c7532447eed)

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
| Fixes: 9e70e985bdc2 ("fs: rework iput logic")
| Reported-by: kernel test robot <[email protected]>
| Reported-by: Julia Lawall <[email protected]>
| Closes: https://lore.kernel.org/r/[email protected]/

cocci warnings: (new ones prefixed by >>)
>> fs/inode.c:1924:45-46: WARNING: atomic_add_unless

vim +1924 fs/inode.c

^1da177e4c3f41 Linus Torvalds 2005-04-16  1899  
^1da177e4c3f41 Linus Torvalds 2005-04-16  1900  /**
^1da177e4c3f41 Linus Torvalds 2005-04-16  1901   *	iput	- put an inode
^1da177e4c3f41 Linus Torvalds 2005-04-16  1902   *	@inode: inode to put
^1da177e4c3f41 Linus Torvalds 2005-04-16  1903   *
^1da177e4c3f41 Linus Torvalds 2005-04-16  1904   *	Puts an inode, dropping its usage count. If the inode use count hits
^1da177e4c3f41 Linus Torvalds 2005-04-16  1905   *	zero, the inode is then freed and may also be destroyed.
^1da177e4c3f41 Linus Torvalds 2005-04-16  1906   *
^1da177e4c3f41 Linus Torvalds 2005-04-16  1907   *	Consequently, iput() can sleep.
^1da177e4c3f41 Linus Torvalds 2005-04-16  1908   */
^1da177e4c3f41 Linus Torvalds 2005-04-16  1909  void iput(struct inode *inode)
^1da177e4c3f41 Linus Torvalds 2005-04-16  1910  {
9e70e985bdc2c6 Josef Bacik    2025-08-26  1911  	if (unlikely(!inode))
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1912  		return;
9e70e985bdc2c6 Josef Bacik    2025-08-26  1913  
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1914  retry:
9e70e985bdc2c6 Josef Bacik    2025-08-26  1915  	lockdep_assert_not_held(&inode->i_lock);
9e70e985bdc2c6 Josef Bacik    2025-08-26  1916  	VFS_BUG_ON_INODE(inode->i_state & I_CLEAR, inode);
9e70e985bdc2c6 Josef Bacik    2025-08-26  1917  	/*
9e70e985bdc2c6 Josef Bacik    2025-08-26  1918  	 * Note this assert is technically racy as if the count is bogusly
9e70e985bdc2c6 Josef Bacik    2025-08-26  1919  	 * equal to one, then two CPUs racing to further drop it can both
9e70e985bdc2c6 Josef Bacik    2025-08-26  1920  	 * conclude it's fine.
9e70e985bdc2c6 Josef Bacik    2025-08-26  1921  	 */
9e70e985bdc2c6 Josef Bacik    2025-08-26  1922  	VFS_BUG_ON_INODE(atomic_read(&inode->i_count) < 1, inode);
9e70e985bdc2c6 Josef Bacik    2025-08-26  1923  
9e70e985bdc2c6 Josef Bacik    2025-08-26 @1924  	if (atomic_add_unless(&inode->i_count, -1, 1))
9e70e985bdc2c6 Josef Bacik    2025-08-26  1925  		return;
9e70e985bdc2c6 Josef Bacik    2025-08-26  1926  
9e70e985bdc2c6 Josef Bacik    2025-08-26  1927  	if ((inode->i_state & I_DIRTY_TIME) && inode->i_nlink) {
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1928  		trace_writeback_lazytime_iput(inode);
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1929  		mark_inode_dirty_sync(inode);
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1930  		goto retry;
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1931  	}
9e70e985bdc2c6 Josef Bacik    2025-08-26  1932  
9e70e985bdc2c6 Josef Bacik    2025-08-26  1933  	spin_lock(&inode->i_lock);
9e70e985bdc2c6 Josef Bacik    2025-08-26  1934  	if (unlikely((inode->i_state & I_DIRTY_TIME) && inode->i_nlink)) {
9e70e985bdc2c6 Josef Bacik    2025-08-26  1935  		spin_unlock(&inode->i_lock);
9e70e985bdc2c6 Josef Bacik    2025-08-26  1936  		goto retry;
^1da177e4c3f41 Linus Torvalds 2005-04-16  1937  	}
9e70e985bdc2c6 Josef Bacik    2025-08-26  1938  
9e70e985bdc2c6 Josef Bacik    2025-08-26  1939  	if (!atomic_dec_and_test(&inode->i_count)) {
9e70e985bdc2c6 Josef Bacik    2025-08-26  1940  		spin_unlock(&inode->i_lock);
9e70e985bdc2c6 Josef Bacik    2025-08-26  1941  		return;
9e70e985bdc2c6 Josef Bacik    2025-08-26  1942  	}
9e70e985bdc2c6 Josef Bacik    2025-08-26  1943  
9e70e985bdc2c6 Josef Bacik    2025-08-26  1944  	/*
9e70e985bdc2c6 Josef Bacik    2025-08-26  1945  	 * iput_final() drops ->i_lock, we can't assert on it as the inode may
9e70e985bdc2c6 Josef Bacik    2025-08-26  1946  	 * be deallocated by the time the call returns.
9e70e985bdc2c6 Josef Bacik    2025-08-26  1947  	 */
9e70e985bdc2c6 Josef Bacik    2025-08-26  1948  	iput_final(inode);
^1da177e4c3f41 Linus Torvalds 2005-04-16  1949  }
^1da177e4c3f41 Linus Torvalds 2005-04-16  1950  EXPORT_SYMBOL(iput);
^1da177e4c3f41 Linus Torvalds 2005-04-16  1951  

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