tree: https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git randconfig-v5.12 head: fd21c2581b744639b5207c11651ab40abf13701a commit: aeb172ab4efb38a4817cf99c9c977d89130c3937 [390/597] pci: s390: remove redundant zbus->bus member config: s390-randconfig-r001-20210318 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project fcc1ce00931751ac02498986feb37744e9ace8de) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install s390 cross compiling tool for clang build # apt-get install binutils-s390x-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/commi... git remote add arnd-playground https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git git fetch --no-tags arnd-playground randconfig-v5.12 git checkout aeb172ab4efb38a4817cf99c9c977d89130c3937 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): In file included from arch/s390/pci/pci_bus.c:14: In file included from include/linux/slab.h:15: In file included from include/linux/gfp.h:6: In file included from include/linux/mmzone.h:8: In file included from include/linux/spinlock.h:59: In file included from include/linux/lockdep.h:14: In file included from include/linux/smp.h:84: arch/s390/include/asm/smp.h:42:1: warning: function 'smp_stop_cpu' could be declared with attribute 'noreturn' [-Wmissing-noreturn] { ^ In file included from arch/s390/pci/pci_bus.c:20: In file included from include/linux/pci.h:39: In file included from include/linux/io.h:13: In file included from arch/s390/include/asm/io.h:80: include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __raw_readb(PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:36:59: note: expanded from macro '__le16_to_cpu' #define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x)) ^ include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16' #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) ^ In file included from arch/s390/pci/pci_bus.c:20: In file included from include/linux/pci.h:39: In file included from include/linux/io.h:13: In file included from arch/s390/include/asm/io.h:80: include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32' #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x)) ^ In file included from arch/s390/pci/pci_bus.c:20: In file included from include/linux/pci.h:39: In file included from include/linux/io.h:13: In file included from arch/s390/include/asm/io.h:80: include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writeb(value, PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ bridge->ops = ops; ^~~~~~ arch/s390/pci/pci_bus.c:198:32: note: initialize the variable 'bridge' to silence this warning struct pci_host_bridge *bridge; ^ = NULL 14 warnings generated. vim +/bridge +219 arch/s390/pci/pci_bus.c 44510d6fa0c00a Pierre Morel 2020-04-22 195 44510d6fa0c00a Pierre Morel 2020-04-22 196 int zpci_bus_device_register(struct zpci_dev *zdev, struct pci_ops *ops) 44510d6fa0c00a Pierre Morel 2020-04-22 197 { a33ad04d2320ed Arnd Bergmann 2020-12-18 198 struct pci_host_bridge *bridge; 44510d6fa0c00a Pierre Morel 2020-04-22 199 struct zpci_bus *zbus = NULL; 44510d6fa0c00a Pierre Morel 2020-04-22 200 int rc = -EBADF; 44510d6fa0c00a Pierre Morel 2020-04-22 201 05bc1be6db4b26 Pierre Morel 2020-03-23 202 if (zpci_nb_devices == ZPCI_NR_DEVICES) { 05bc1be6db4b26 Pierre Morel 2020-03-23 203 pr_warn("Adding PCI function %08x failed because the configured limit of %d is reached\n", 05bc1be6db4b26 Pierre Morel 2020-03-23 204 zdev->fid, ZPCI_NR_DEVICES); 05bc1be6db4b26 Pierre Morel 2020-03-23 205 return -ENOSPC; 05bc1be6db4b26 Pierre Morel 2020-03-23 206 } 05bc1be6db4b26 Pierre Morel 2020-03-23 207 zpci_nb_devices++; 05bc1be6db4b26 Pierre Morel 2020-03-23 208 44510d6fa0c00a Pierre Morel 2020-04-22 209 if (zdev->devfn >= ZPCI_FUNCTIONS_PER_BUS) 05bc1be6db4b26 Pierre Morel 2020-03-23 210 return -EINVAL; 05bc1be6db4b26 Pierre Morel 2020-03-23 211 44510d6fa0c00a Pierre Morel 2020-04-22 212 if (!s390_pci_no_rid && zdev->rid_available) 44510d6fa0c00a Pierre Morel 2020-04-22 213 zbus = zpci_bus_get(zdev->pchid); 44510d6fa0c00a Pierre Morel 2020-04-22 214 44510d6fa0c00a Pierre Morel 2020-04-22 215 if (!zbus) { 05bc1be6db4b26 Pierre Morel 2020-03-23 216 zbus = zpci_bus_alloc(zdev->pchid); 05bc1be6db4b26 Pierre Morel 2020-03-23 217 if (!zbus) 05bc1be6db4b26 Pierre Morel 2020-03-23 218 return -ENOMEM; a33ad04d2320ed Arnd Bergmann 2020-12-18 @219 bridge->ops = ops; 44510d6fa0c00a Pierre Morel 2020-04-22 220 } 05bc1be6db4b26 Pierre Morel 2020-03-23 221 05bc1be6db4b26 Pierre Morel 2020-03-23 222 zdev->zbus = zbus; a33ad04d2320ed Arnd Bergmann 2020-12-18 223 44510d6fa0c00a Pierre Morel 2020-04-22 224 if (zbus->function[zdev->devfn]) { 44510d6fa0c00a Pierre Morel 2020-04-22 225 pr_err("devfn %04x is already assigned\n", zdev->devfn); 44510d6fa0c00a Pierre Morel 2020-04-22 226 goto error; /* rc already set */ 44510d6fa0c00a Pierre Morel 2020-04-22 227 } 44510d6fa0c00a Pierre Morel 2020-04-22 228 zbus->function[zdev->devfn] = zdev; 05bc1be6db4b26 Pierre Morel 2020-03-23 229 a33ad04d2320ed Arnd Bergmann 2020-12-18 230 zpci_setup_bus_resources(zdev, &zbus->bridge->windows); 05bc1be6db4b26 Pierre Morel 2020-03-23 231 aeb172ab4efb38 Arnd Bergmann 2021-01-25 232 if (zbus->bridge->bus) { 44510d6fa0c00a Pierre Morel 2020-04-22 233 if (!zbus->multifunction) { 44510d6fa0c00a Pierre Morel 2020-04-22 234 WARN_ONCE(1, "zbus is not multifunction\n"); 44510d6fa0c00a Pierre Morel 2020-04-22 235 goto error_bus; 44510d6fa0c00a Pierre Morel 2020-04-22 236 } 44510d6fa0c00a Pierre Morel 2020-04-22 237 if (!zdev->rid_available) { 44510d6fa0c00a Pierre Morel 2020-04-22 238 WARN_ONCE(1, "rid_available not set for multifunction\n"); 44510d6fa0c00a Pierre Morel 2020-04-22 239 goto error_bus; 44510d6fa0c00a Pierre Morel 2020-04-22 240 } 44510d6fa0c00a Pierre Morel 2020-04-22 241 rc = zpci_bus_add_device(zbus, zdev); 44510d6fa0c00a Pierre Morel 2020-04-22 242 if (rc) 44510d6fa0c00a Pierre Morel 2020-04-22 243 goto error_bus; 44510d6fa0c00a Pierre Morel 2020-04-22 244 } else if (zdev->devfn == 0) { 44510d6fa0c00a Pierre Morel 2020-04-22 245 if (zbus->multifunction && !zdev->rid_available) { 44510d6fa0c00a Pierre Morel 2020-04-22 246 WARN_ONCE(1, "rid_available not set on function 0 for multifunction\n"); 44510d6fa0c00a Pierre Morel 2020-04-22 247 goto error_bus; 44510d6fa0c00a Pierre Morel 2020-04-22 248 } aeb172ab4efb38 Arnd Bergmann 2021-01-25 249 rc = zpci_bus_scan(zbus, (u16)zdev->uid); 44510d6fa0c00a Pierre Morel 2020-04-22 250 if (rc) 44510d6fa0c00a Pierre Morel 2020-04-22 251 goto error_bus; 44510d6fa0c00a Pierre Morel 2020-04-22 252 zpci_bus_add_devices(zbus); 44510d6fa0c00a Pierre Morel 2020-04-22 253 rc = zpci_init_slot(zdev); 44510d6fa0c00a Pierre Morel 2020-04-22 254 if (rc) 44510d6fa0c00a Pierre Morel 2020-04-22 255 goto error_bus; 44510d6fa0c00a Pierre Morel 2020-04-22 256 zdev->has_hp_slot = 1; 44510d6fa0c00a Pierre Morel 2020-04-22 257 zbus->multifunction = zdev->rid_available; 44510d6fa0c00a Pierre Morel 2020-04-22 258 zbus->max_bus_speed = zdev->max_bus_speed; 44510d6fa0c00a Pierre Morel 2020-04-22 259 } else { 44510d6fa0c00a Pierre Morel 2020-04-22 260 zbus->multifunction = 1; 44510d6fa0c00a Pierre Morel 2020-04-22 261 } 44510d6fa0c00a Pierre Morel 2020-04-22 262 05bc1be6db4b26 Pierre Morel 2020-03-23 263 return 0; 05bc1be6db4b26 Pierre Morel 2020-03-23 264 44510d6fa0c00a Pierre Morel 2020-04-22 265 error_bus: 44510d6fa0c00a Pierre Morel 2020-04-22 266 zpci_nb_devices--; 44510d6fa0c00a Pierre Morel 2020-04-22 267 zbus->function[zdev->devfn] = NULL; 44510d6fa0c00a Pierre Morel 2020-04-22 268 error: 05bc1be6db4b26 Pierre Morel 2020-03-23 269 pr_err("Adding PCI function %08x failed\n", zdev->fid); 05bc1be6db4b26 Pierre Morel 2020-03-23 270 zpci_bus_put(zbus); 05bc1be6db4b26 Pierre Morel 2020-03-23 271 return rc; 05bc1be6db4b26 Pierre Morel 2020-03-23 272 } 05bc1be6db4b26 Pierre Morel 2020-03-23 273 :::::: The code at line 219 was first introduced by commit :::::: a33ad04d2320edeaca80d61524768a9b7b7af8e4 s390: simplify PCI bus scan :::::: TO: Arnd Bergmann <arnd(a)arndb.de&gt; :::::: CC: Arnd Bergmann <arnd(a)arndb.de&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org