[linux-next:master 1128/2532] drivers/pwm/core.c:1530 pwm_put() warn: variable dereferenced before check 'pwm' (see line 1528)

[kernel test robot <lkp@intel.com>]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   a6bd6c9333397f5a0e2667d4d82fef8c970108f2
commit: d60bc2995732489766cbe650fc367e036ff6a0e0 [1128/2532] pwm: Add a struct device to struct pwm_chip
:::::: branch date: 3 days ago
:::::: commit date: 6 days ago
config: m68k-randconfig-r071-20240326 (https://download.01.org/0day-ci/archive/20240331/202403312030.QYCgiAey-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 13.2.0

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 <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202403312030.QYCgiAey-lkp@intel.com/

smatch warnings:
drivers/pwm/core.c:1530 pwm_put() warn: variable dereferenced before check 'pwm' (see line 1528)

vim +/pwm +1530 drivers/pwm/core.c

8138d2ddbcca2a Thierry Reding   2012-03-26  1521  
8138d2ddbcca2a Thierry Reding   2012-03-26  1522  /**
8138d2ddbcca2a Thierry Reding   2012-03-26  1523   * pwm_put() - release a PWM device
8138d2ddbcca2a Thierry Reding   2012-03-26  1524   * @pwm: PWM device
8138d2ddbcca2a Thierry Reding   2012-03-26  1525   */
8138d2ddbcca2a Thierry Reding   2012-03-26  1526  void pwm_put(struct pwm_device *pwm)
8138d2ddbcca2a Thierry Reding   2012-03-26  1527  {
d60bc299573248 Uwe Kleine-König 2024-03-17 @1528  	struct pwm_chip *chip = pwm->chip;
d60bc299573248 Uwe Kleine-König 2024-03-17  1529  
8138d2ddbcca2a Thierry Reding   2012-03-26 @1530  	if (!pwm)
8138d2ddbcca2a Thierry Reding   2012-03-26  1531  		return;
8138d2ddbcca2a Thierry Reding   2012-03-26  1532  
8138d2ddbcca2a Thierry Reding   2012-03-26  1533  	mutex_lock(&pwm_lock);
8138d2ddbcca2a Thierry Reding   2012-03-26  1534  
8138d2ddbcca2a Thierry Reding   2012-03-26  1535  	if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
e50d3523ff4564 Sachin Kamat     2012-08-10  1536  		pr_warn("PWM device already freed\n");
8138d2ddbcca2a Thierry Reding   2012-03-26  1537  		goto out;
8138d2ddbcca2a Thierry Reding   2012-03-26  1538  	}
8138d2ddbcca2a Thierry Reding   2012-03-26  1539  
d60bc299573248 Uwe Kleine-König 2024-03-17  1540  	if (chip->ops->free)
8138d2ddbcca2a Thierry Reding   2012-03-26  1541  		pwm->chip->ops->free(pwm->chip, pwm);
8138d2ddbcca2a Thierry Reding   2012-03-26  1542  
8138d2ddbcca2a Thierry Reding   2012-03-26  1543  	pwm->label = NULL;
8138d2ddbcca2a Thierry Reding   2012-03-26  1544  
d60bc299573248 Uwe Kleine-König 2024-03-17  1545  	put_device(&chip->dev);
d60bc299573248 Uwe Kleine-König 2024-03-17  1546  
d60bc299573248 Uwe Kleine-König 2024-03-17  1547  	module_put(chip->owner);
8138d2ddbcca2a Thierry Reding   2012-03-26  1548  out:
8138d2ddbcca2a Thierry Reding   2012-03-26  1549  	mutex_unlock(&pwm_lock);
8138d2ddbcca2a Thierry Reding   2012-03-26  1550  }
8138d2ddbcca2a Thierry Reding   2012-03-26  1551  EXPORT_SYMBOL_GPL(pwm_put);
8138d2ddbcca2a Thierry Reding   2012-03-26  1552  

:::::: The code at line 1530 was first introduced by commit
:::::: 8138d2ddbcca2a100482dac390133f83c5a60f94 pwm: Add table-based lookup for static mappings

:::::: TO: Thierry Reding <thierry.reding@avionic-design.de>
:::::: CC: Thierry Reding <thierry.reding@avionic-design.de>

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https://github.com/intel/lkp-tests/wiki