drivers/net/wireless/mediatek/mt76/mt7996/mac.c:1651 mt7996_msdu_page_get_from_cache() warn: can 'p' even be NULL?

drivers/net/wireless/mediatek/mt76/mt7996/mac.c:1651 mt7996_msdu_page_get_from_cache() warn: can 'p' even be NULL?

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-kernel@vger.kernel.org
TO: Rex Lu <rex.lu@mediatek.com>
CC: Felix Fietkau <nbd@nbd.name>
CC: Lorenzo Bianconi <lorenzo@kernel.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   ec714e371f22f716a04e6ecb2a24988c92b26911
commit: b1e58e137b61693f12da037d2d50aca9c2140a43 wifi: mt76: mt7996: Introduce RRO MSDU callbacks
date:   3 weeks ago
:::::: branch date: 15 hours ago
:::::: commit date: 3 weeks ago
config: x86_64-randconfig-161-20251009 (https://download.01.org/0day-ci/archive/20251010/202510100155.MS0IXhzm-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)

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/202510100155.MS0IXhzm-lkp@intel.com/

New smatch warnings:
drivers/net/wireless/mediatek/mt76/mt7996/mac.c:1651 mt7996_msdu_page_get_from_cache() warn: can 'p' even be NULL?

Old smatch warnings:
drivers/net/wireless/mediatek/mt76/mt7996/mac.c:483 mt7996_mac_fill_rx() warn: potential spectre issue 'dev->mt76.phys' [r]
drivers/net/wireless/mediatek/mt76/mt7996/mac.c:484 mt7996_mac_fill_rx() warn: possible spectre second half.  'mphy'
drivers/net/wireless/mediatek/mt76/mt7996/mac.c:3061 mt7996_mac_twt_sched_list_add() error: uninitialized symbol 'start_tsf'.

vim +/p +1651 drivers/net/wireless/mediatek/mt76/mt7996/mac.c

98686cd21624c7 Shayne Chen 2022-11-22  1640  
b1e58e137b6169 Rex Lu      2025-09-09  1641  static struct mt7996_msdu_page *
b1e58e137b6169 Rex Lu      2025-09-09  1642  mt7996_msdu_page_get_from_cache(struct mt7996_dev *dev)
b1e58e137b6169 Rex Lu      2025-09-09  1643  {
b1e58e137b6169 Rex Lu      2025-09-09  1644  	struct mt7996_msdu_page *p = NULL;
b1e58e137b6169 Rex Lu      2025-09-09  1645  
b1e58e137b6169 Rex Lu      2025-09-09  1646  	spin_lock(&dev->wed_rro.lock);
b1e58e137b6169 Rex Lu      2025-09-09  1647  
b1e58e137b6169 Rex Lu      2025-09-09  1648  	if (!list_empty(&dev->wed_rro.page_cache)) {
b1e58e137b6169 Rex Lu      2025-09-09  1649  		p = list_first_entry(&dev->wed_rro.page_cache,
b1e58e137b6169 Rex Lu      2025-09-09  1650  				     struct mt7996_msdu_page, list);
b1e58e137b6169 Rex Lu      2025-09-09 @1651  		if (p)
b1e58e137b6169 Rex Lu      2025-09-09  1652  			list_del(&p->list);
b1e58e137b6169 Rex Lu      2025-09-09  1653  	}
b1e58e137b6169 Rex Lu      2025-09-09  1654  
b1e58e137b6169 Rex Lu      2025-09-09  1655  	spin_unlock(&dev->wed_rro.lock);
b1e58e137b6169 Rex Lu      2025-09-09  1656  
b1e58e137b6169 Rex Lu      2025-09-09  1657  	return p;
b1e58e137b6169 Rex Lu      2025-09-09  1658  }
b1e58e137b6169 Rex Lu      2025-09-09  1659  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

drivers/net/wireless/mediatek/mt76/mt7996/mac.c:1651 mt7996_msdu_page_get_from_cache() warn: can 'p' even be NULL?

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   ec714e371f22f716a04e6ecb2a24988c92b26911
commit: b1e58e137b61693f12da037d2d50aca9c2140a43 wifi: mt76: mt7996: Introduce RRO MSDU callbacks
date:   3 weeks ago
config: x86_64-randconfig-161-20251009 (https://download.01.org/0day-ci/archive/20251010/202510100155.MS0IXhzm-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)

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/202510100155.MS0IXhzm-lkp@intel.com/

New smatch warnings:
drivers/net/wireless/mediatek/mt76/mt7996/mac.c:1651 mt7996_msdu_page_get_from_cache() warn: can 'p' even be NULL?

vim +/p +1651 drivers/net/wireless/mediatek/mt76/mt7996/mac.c

b1e58e137b6169 Rex Lu      2025-09-09  1641  static struct mt7996_msdu_page *
b1e58e137b6169 Rex Lu      2025-09-09  1642  mt7996_msdu_page_get_from_cache(struct mt7996_dev *dev)
b1e58e137b6169 Rex Lu      2025-09-09  1643  {
b1e58e137b6169 Rex Lu      2025-09-09  1644  	struct mt7996_msdu_page *p = NULL;
b1e58e137b6169 Rex Lu      2025-09-09  1645  
b1e58e137b6169 Rex Lu      2025-09-09  1646  	spin_lock(&dev->wed_rro.lock);
b1e58e137b6169 Rex Lu      2025-09-09  1647  
b1e58e137b6169 Rex Lu      2025-09-09  1648  	if (!list_empty(&dev->wed_rro.page_cache)) {
b1e58e137b6169 Rex Lu      2025-09-09  1649  		p = list_first_entry(&dev->wed_rro.page_cache,
b1e58e137b6169 Rex Lu      2025-09-09  1650  				     struct mt7996_msdu_page, list);
b1e58e137b6169 Rex Lu      2025-09-09 @1651  		if (p)

This NULL check is pointless.  We already ensured that the list is not
empty.

b1e58e137b6169 Rex Lu      2025-09-09  1652  			list_del(&p->list);
b1e58e137b6169 Rex Lu      2025-09-09  1653  	}
b1e58e137b6169 Rex Lu      2025-09-09  1654  
b1e58e137b6169 Rex Lu      2025-09-09  1655  	spin_unlock(&dev->wed_rro.lock);
b1e58e137b6169 Rex Lu      2025-09-09  1656  
b1e58e137b6169 Rex Lu      2025-09-09  1657  	return p;
b1e58e137b6169 Rex Lu      2025-09-09  1658  }


-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki