arch/s390/pci/pci_bus.c:312:3: warning: calling function 'zpci_bus_put' requires holding mutex 'pci_rescan_remove_lock' exclusively

arch/s390/pci/pci_bus.c:312:3: warning: calling function 'zpci_bus_put' requires holding mutex 'pci_rescan_remove_lock' exclusively

[kernel test robot]

tree:   https://github.com/intel-lab-lkp/linux/commits/Benjamin-Block/PCI-IOV-Make-pci_lock_rescan_remove-reentrant-and-protect-sriov_add_vfs-sriov_del_vfs/20260924-182927
head:   ca5e1336f1cf45fbd7a38048643bceed16b522a9
commit: ca5e1336f1cf45fbd7a38048643bceed16b522a9 s390/pci: Fix circular/recursive deadlocks in PCI-bus and -device release
date:   6 days ago
config: s390-randconfig-2000-20260930 (https://download.01.org/0day-ci/archive/20260930/202609301529.u3dcGRKQ-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 1f84168f595dab2e23aab4181997da0a7f486dc7)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260930/202609301529.u3dcGRKQ-lkp@intel.com/reproduce)

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609301529.u3dcGRKQ-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/s390/pci/pci_bus.c:312:3: warning: calling function 'zpci_bus_put' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
     312 |                 zpci_bus_put(curp);
         |                 ^
   arch/s390/pci/pci_bus.c:445:3: warning: calling function 'zpci_bus_put' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
     445 |                 zpci_bus_put(zbus);
         |                 ^
   arch/s390/pci/pci_bus.c:473:2: warning: calling function 'zpci_bus_put' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
     473 |         zpci_bus_put(zbus);
         |         ^
   arch/s390/pci/pci_bus.c:483:2: warning: calling function 'zpci_bus_put' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
     483 |         zpci_bus_put(zbus);
         |         ^
   4 warnings generated.
--
>> arch/s390/pci/pci.c:638:2: warning: calling function 'zpci_zdev_put' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
     638 |         zpci_zdev_put(zdev);
         |         ^
   arch/s390/pci/pci.c:979:2: warning: calling function 'zpci_zdev_put' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
     979 |         zpci_zdev_put(zdev);
         |         ^
>> arch/s390/pci/pci.c:1000:3: warning: calling function 'zpci_cleanup_bus_resources' requires holding mutex 'pci_rescan_remove_lock' exclusively [-Wthread-safety-analysis]
    1000 |                 zpci_cleanup_bus_resources(zdev);
         |                 ^
   3 warnings generated.


vim +312 arch/s390/pci/pci_bus.c

44510d6fa0c00a Pierre Morel   2020-04-22  276  
4cb92fa763823d Benjamin Block 2025-12-05  277  /**
4cb92fa763823d Benjamin Block 2025-12-05  278   * zpci_bus_get_next - get the next zbus object from given position in the list
4cb92fa763823d Benjamin Block 2025-12-05  279   * @pos:	current position/cursor in the global zbus list
4cb92fa763823d Benjamin Block 2025-12-05  280   *
4cb92fa763823d Benjamin Block 2025-12-05  281   * Acquires and releases references as the cursor iterates (might also free/
4cb92fa763823d Benjamin Block 2025-12-05  282   * release the cursor). Is tolerant of concurrent operations on the list.
4cb92fa763823d Benjamin Block 2025-12-05  283   *
4cb92fa763823d Benjamin Block 2025-12-05  284   * To begin the iteration, set *@pos to %NULL before calling the function.
4cb92fa763823d Benjamin Block 2025-12-05  285   *
4cb92fa763823d Benjamin Block 2025-12-05  286   * *@pos is set to %NULL in cases where either the list is empty, or *@pos is
4cb92fa763823d Benjamin Block 2025-12-05  287   * the last element in the list.
4cb92fa763823d Benjamin Block 2025-12-05  288   *
4cb92fa763823d Benjamin Block 2025-12-05  289   * Context: Process context. May sleep.
4cb92fa763823d Benjamin Block 2025-12-05  290   */
4cb92fa763823d Benjamin Block 2025-12-05  291  void zpci_bus_get_next(struct zpci_bus **pos)
4cb92fa763823d Benjamin Block 2025-12-05  292  {
4cb92fa763823d Benjamin Block 2025-12-05  293  	struct zpci_bus *curp = *pos, *next = NULL;
4cb92fa763823d Benjamin Block 2025-12-05  294  
4cb92fa763823d Benjamin Block 2025-12-05  295  	mutex_lock(&zbus_list_lock);
4cb92fa763823d Benjamin Block 2025-12-05  296  	if (curp)
4cb92fa763823d Benjamin Block 2025-12-05  297  		next = list_next_entry(curp, bus_next);
4cb92fa763823d Benjamin Block 2025-12-05  298  	else
4cb92fa763823d Benjamin Block 2025-12-05  299  		next = list_first_entry(&zbus_list, typeof(*curp), bus_next);
4cb92fa763823d Benjamin Block 2025-12-05  300  
4cb92fa763823d Benjamin Block 2025-12-05  301  	if (list_entry_is_head(next, &zbus_list, bus_next))
4cb92fa763823d Benjamin Block 2025-12-05  302  		next = NULL;
4cb92fa763823d Benjamin Block 2025-12-05  303  
4cb92fa763823d Benjamin Block 2025-12-05  304  	if (next)
4cb92fa763823d Benjamin Block 2025-12-05  305  		__zpci_bus_get(next);
4cb92fa763823d Benjamin Block 2025-12-05  306  
4cb92fa763823d Benjamin Block 2025-12-05  307  	*pos = next;
4cb92fa763823d Benjamin Block 2025-12-05  308  	mutex_unlock(&zbus_list_lock);
4cb92fa763823d Benjamin Block 2025-12-05  309  
4cb92fa763823d Benjamin Block 2025-12-05  310  	/* zpci_bus_put() might drop refcount to 0 and locks zbus_list_lock */
4cb92fa763823d Benjamin Block 2025-12-05  311  	if (curp)
4cb92fa763823d Benjamin Block 2025-12-05 @312  		zpci_bus_put(curp);
4cb92fa763823d Benjamin Block 2025-12-05  313  }
4cb92fa763823d Benjamin Block 2025-12-05  314  

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