Hi Kashyap, I love your patch! Perhaps something to improve: [auto build test WARNING on next-20201013] [cannot apply to scsi/for-next mkp-scsi/for-next v5.9 v5.9-rc8 v5.9-rc7 v5.9] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Kashyap-Desai/add-io_uring-with-... base: f2fb1afc57304f9dd68c20a08270e287470af2eb config: powerpc64-randconfig-r006-20201014 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project e7fe3c6dfede8d5781bd000741c3dea7088307a4) 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 powerpc64 cross compiling tool for clang build # apt-get install binutils-powerpc64-linux-gnu # https://github.com/0day-ci/linux/commit/a3173d0d1c2ca8a45007fa994f2641aa7... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Kashyap-Desai/add-io_uring-with-IOPOLL-support-in-scsi-layer/20201014-202916 git checkout a3173d0d1c2ca8a45007fa994f2641aa7262719c # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64 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 drivers/scsi/scsi_debug.c:32: In file included from include/linux/scatterlist.h:9: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:43:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insb, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:29:1: note: expanded from here __do_insb ^ arch/powerpc/include/asm/io.h:541:56: note: expanded from macro '__do_insb' #define __do_insb(p, b, n) readsb((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from drivers/scsi/scsi_debug.c:32: In file included from include/linux/scatterlist.h:9: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:45:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insw, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:31:1: note: expanded from here __do_insw ^ arch/powerpc/include/asm/io.h:542:56: note: expanded from macro '__do_insw' #define __do_insw(p, b, n) readsw((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from drivers/scsi/scsi_debug.c:32: In file included from include/linux/scatterlist.h:9: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:47:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(insl, (unsigned long p, void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:33:1: note: expanded from here __do_insl ^ arch/powerpc/include/asm/io.h:543:56: note: expanded from macro '__do_insl' #define __do_insl(p, b, n) readsl((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from drivers/scsi/scsi_debug.c:32: In file included from include/linux/scatterlist.h:9: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:49:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsb, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:35:1: note: expanded from here __do_outsb ^ arch/powerpc/include/asm/io.h:544:58: note: expanded from macro '__do_outsb' #define __do_outsb(p, b, n) writesb((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from drivers/scsi/scsi_debug.c:32: In file included from include/linux/scatterlist.h:9: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:51:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsw, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:37:1: note: expanded from here __do_outsw ^ arch/powerpc/include/asm/io.h:545:58: note: expanded from macro '__do_outsw' #define __do_outsw(p, b, n) writesw((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ In file included from drivers/scsi/scsi_debug.c:32: In file included from include/linux/scatterlist.h:9: In file included from arch/powerpc/include/asm/io.h:604: arch/powerpc/include/asm/io-defs.h:53:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] DEF_PCI_AC_NORET(outsl, (unsigned long p, const void *b, unsigned long c), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/io.h:601:3: note: expanded from macro 'DEF_PCI_AC_NORET' __do_##name al; \ ^~~~~~~~~~~~~~ <scratch space>:39:1: note: expanded from here __do_outsl ^ arch/powerpc/include/asm/io.h:546:58: note: expanded from macro '__do_outsl' #define __do_outsl(p, b, n) writesl((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) ~~~~~~~~~~~~~~~~~~~~~^ drivers/scsi/scsi_debug.c:5442:3: error: non-void function 'schedule_resp' should return a value [-Wreturn-type] return; ^ int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num) ^ drivers/scsi/scsi_debug.c:7246:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num) ^ static 7 warnings and 1 error generated. vim +/sdebug_blk_mq_poll +7246 drivers/scsi/scsi_debug.c 7245 7247 { 7248 int qc_idx; 7249 int retiring = 0; 7250 unsigned long iflags; 7251 struct sdebug_queue *sqp; 7252 struct sdebug_queued_cmd *sqcp; 7253 struct scsi_cmnd *scp; 7254 struct sdebug_dev_info *devip; 7255 int num_entries = 0; 7256 7257 sqp = sdebug_q_arr + queue_num; 7258 7259 do { 7260 spin_lock_irqsave(&sqp->qc_lock, iflags); 7261 qc_idx = find_first_bit(sqp->in_use_bm, sdebug_max_queue); 7262 if (unlikely((qc_idx < 0) || (qc_idx >= SDEBUG_CANQUEUE))) 7263 goto out; 7264 7265 sqcp = &sqp->qc_arr[qc_idx]; 7266 scp = sqcp->a_cmnd; 7267 if (unlikely(scp == NULL)) { 7268 pr_err("scp is NULL, queue_num=%d, qc_idx=%d from %s\n", 7269 queue_num, qc_idx, __func__); 7270 goto out; 7271 } 7272 devip = (struct sdebug_dev_info *)scp->device->hostdata; 7273 if (likely(devip)) 7274 atomic_dec(&devip->num_in_q); 7275 else 7276 pr_err("devip=NULL from %s\n", __func__); 7277 if (unlikely(atomic_read(&retired_max_queue) > 0)) 7278 retiring = 1; 7279 7280 sqcp->a_cmnd = NULL; 7281 if (unlikely(!test_and_clear_bit(qc_idx, sqp->in_use_bm))) { 7282 pr_err("Unexpected completion sqp %p queue_num=%d qc_idx=%d from %s\n", 7283 sqp, queue_num, qc_idx, __func__); 7284 goto out; 7285 } 7286 7287 if (unlikely(retiring)) { /* user has reduced max_queue */ 7288 int k, retval; 7289 7290 retval = atomic_read(&retired_max_queue); 7291 if (qc_idx >= retval) { 7292 pr_err("index %d too large\n", retval); 7293 goto out; 7294 } 7295 k = find_last_bit(sqp->in_use_bm, retval); 7296 if ((k < sdebug_max_queue) || (k == retval)) 7297 atomic_set(&retired_max_queue, 0); 7298 else 7299 atomic_set(&retired_max_queue, k + 1); 7300 } 7301 spin_unlock_irqrestore(&sqp->qc_lock, iflags); 7302 scp->scsi_done(scp); /* callback to mid level */ 7303 num_entries++; 7304 } while (1); 7305 7306 out: 7307 spin_unlock_irqrestore(&sqp->qc_lock, iflags); 7308 return num_entries; 7309 } 7310 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org