On Fri, Jun 27, 2025 at 04:36:14PM +0200, Paolo Abeni wrote: > On 6/27/25 3:11 PM, Paolo Abeni wrote: > > +csky maintainer > > On 6/27/25 8:41 AM, kernel test robot wrote: > >> Hi Paolo, > >> > >> kernel test robot noticed the following build warnings: > >> > >> [auto build test WARNING on net-next/main] > >> > >> url: > >> https://github.com/intel-lab-lkp/linux/commits/Paolo-Abeni/scripts-kernel_doc-py-properly-handle-VIRTIO_DECLARE_FEATURES/20250624-221751 > >> base: net-next/main > >> patch link: > >> https://lore.kernel.org/r/23e46bff5333015d92bf0876033750d9fbf555a0.1750753211.git.pabeni%40redhat.com > >> patch subject: [PATCH v6 net-next 4/9] vhost-net: allow configuring > >> extended features > >> config: csky-randconfig-001-20250627 > >> (https://download.01.org/0day-ci/archive/20250627/202506271443.g9cax8ps-...@intel.com/config) > >> compiler: csky-linux-gcc (GCC) 15.1.0 > >> reproduce (this is a W=1 build): > >> (https://download.01.org/0day-ci/archive/20250627/202506271443.g9cax8ps-...@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 <l...@intel.com> > >> | Closes: > >> https://lore.kernel.org/oe-kbuild-all/202506271443.g9cax8ps-...@intel.com/ > >> > >> All warnings (new ones prefixed by >>): > >> > >> In file included from include/linux/uaccess.h:12, > >> from include/linux/sched/task.h:13, > >> from include/linux/sched/signal.h:9, > >> from include/linux/rcuwait.h:6, > >> from include/linux/percpu-rwsem.h:7, > >> from include/linux/fs.h:34, > >> from include/linux/compat.h:17, > >> from drivers/vhost/net.c:8: > >> arch/csky/include/asm/uaccess.h: In function '__get_user_fn.constprop': > >>>> arch/csky/include/asm/uaccess.h:147:9: warning: 'retval' is used > >>>> uninitialized [-Wuninitialized] > >> 147 | __asm__ __volatile__( \ > >> | ^~~~~~~ > >> arch/csky/include/asm/uaccess.h:187:17: note: in expansion of macro > >> '__get_user_asm_64' > >> 187 | __get_user_asm_64(x, ptr, retval); > >> | ^~~~~~~~~~~~~~~~~ > >> arch/csky/include/asm/uaccess.h:170:13: note: 'retval' was declared here > >> 170 | int retval; > >> | ^~~~~~ > >> > >> > >> vim +/retval +147 arch/csky/include/asm/uaccess.h > >> > >> da551281947cb2c Guo Ren 2018-09-05 141 > >> e58a41c2226847f Guo Ren 2021-04-21 142 #define __get_user_asm_64(x, ptr, > >> err) \ > >> da551281947cb2c Guo Ren 2018-09-05 143 do { > >> \ > >> da551281947cb2c Guo Ren 2018-09-05 144 int tmp; > >> \ > >> e58a41c2226847f Guo Ren 2021-04-21 145 int errcode; > >> \ > >> e58a41c2226847f Guo Ren 2021-04-21 146 > >> \ > >> e58a41c2226847f Guo Ren 2021-04-21 @147 __asm__ __volatile__( > >> \ > >> e58a41c2226847f Guo Ren 2021-04-21 148 "1: ldw %3, (%2, 0) > >> \n" \ > >> da551281947cb2c Guo Ren 2018-09-05 149 " stw %3, (%1, 0) > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 150 "2: ldw %3, (%2, 4) > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 151 " stw %3, (%1, 4) > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 152 " br 4f > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 153 "3: mov %0, %4 > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 154 " br 4f > >> \n" \ > >> da551281947cb2c Guo Ren 2018-09-05 155 ".section __ex_table, \"a\" > >> \n" \ > >> da551281947cb2c Guo Ren 2018-09-05 156 ".align 2 > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 157 ".long 1b, 3b > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 158 ".long 2b, 3b > >> \n" \ > >> da551281947cb2c Guo Ren 2018-09-05 159 ".previous > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 160 "4: > >> \n" \ > >> e58a41c2226847f Guo Ren 2021-04-21 161 : "=r"(err), "=r"(x), > >> "=r"(ptr), \ > >> e58a41c2226847f Guo Ren 2021-04-21 162 "=r"(tmp), "=r"(errcode) > >> \ > >> e58a41c2226847f Guo Ren 2021-04-21 163 : "0"(err), "1"(x), "2"(ptr), > >> "3"(0), \ > >> e58a41c2226847f Guo Ren 2021-04-21 164 "4"(-EFAULT) > >> \ > >> da551281947cb2c Guo Ren 2018-09-05 165 : "memory"); > >> \ > >> da551281947cb2c Guo Ren 2018-09-05 166 } while (0) > >> da551281947cb2c Guo Ren 2018-09-05 167 > > > > The intel test report reported the above compile warning on this series: > > > > https://lore.kernel.org/netdev/20250627084609-mutt-send-email-...@kernel.org/T/#md788de2b3a4e9da23ac93b5f1c773a6070b5b4fb > > > > specifically, in patch 4: > > > > + if (get_user(features, featurep + 1 + i)) > > + return -EFAULT; > > > > AFAICS such statement is legit, and the bot points to some problem in > > the arch specific get_user() implementation. Could you please have a look? > > Out of sheer ignorance on my side, I fail to see how the csky get_user() > could work correctly without something alike the following (which indeed > fixes the issue here). > > /P > --- > diff --git a/arch/csky/include/asm/uaccess.h > b/arch/csky/include/asm/uaccess.h > index 2e927c21d8a1..ae0864ad59a3 100644 > --- a/arch/csky/include/asm/uaccess.h > +++ b/arch/csky/include/asm/uaccess.h > @@ -167,7 +167,7 @@ do { > \ > > static inline int __get_user_fn(size_t size, const void __user *ptr, > void *x) > { > - int retval; > + int retval = 0; > u32 tmp; > > switch (size) {
Given there's no reaction from the arch maintainers, I see two options: - go back to copy_from_user - nothing wrong with it, and the code in question is off data path. - go ahead and include this patch in the series, even though I'm just as unsure it's right as you are. Up to you really, but I think it's one of the two. -- MST
