* [linux-next:master 1888/2633] kernel/rcu/refscale.c:479:3: warning: variable 'x' is uninitialized when used here
@ 2021-05-12 11:38 kernel test robot
2021-05-13 17:48 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: kernel test robot @ 2021-05-12 11:38 UTC (permalink / raw)
To: Paul E. McKenney
Cc: kbuild-all, clang-built-linux, Linux Memory Management List
[-- Attachment #1: Type: text/plain, Size: 2747 bytes --]
tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head: ec85c95b0c90a17413901b018e8ade7b9eae7cad
commit: 4b46fcb7f1a6a202e3f77ce377079b4243d1be6f [1888/2633] refscale: Add measurement of clock readout
config: riscv-randconfig-r022-20210512 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project a0fed635fe1701470062495a6ffee1c608f3f1bc)
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 riscv cross compiling tool for clang build
# apt-get install binutils-riscv64-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=4b46fcb7f1a6a202e3f77ce377079b4243d1be6f
git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git fetch --no-tags linux-next master
git checkout 4b46fcb7f1a6a202e3f77ce377079b4243d1be6f
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=riscv
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> kernel/rcu/refscale.c:479:3: warning: variable 'x' is uninitialized when used here [-Wuninitialized]
x += ktime_get_real_fast_ns();
^
kernel/rcu/refscale.c:474:7: note: initialize the variable 'x' to silence this warning
u64 x;
^
= 0
kernel/rcu/refscale.c:492:3: warning: variable 'x' is uninitialized when used here [-Wuninitialized]
x += ktime_get_real_fast_ns();
^
kernel/rcu/refscale.c:487:7: note: initialize the variable 'x' to silence this warning
u64 x;
^
= 0
2 warnings generated.
Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for LOCKDEP
Depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT && (FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86)
Selected by
- DEBUG_LOCK_ALLOC && DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
vim +/x +479 kernel/rcu/refscale.c
471
472 static void ref_clock_section(const int nloops)
473 {
474 u64 x;
475 int i;
476
477 preempt_disable();
478 for (i = nloops; i >= 0; i--) {
> 479 x += ktime_get_real_fast_ns();
480 }
481 preempt_enable();
482 stopopts = x;
483 }
484
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 29280 bytes --]
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [linux-next:master 1888/2633] kernel/rcu/refscale.c:479:3: warning: variable 'x' is uninitialized when used here
2021-05-12 11:38 [linux-next:master 1888/2633] kernel/rcu/refscale.c:479:3: warning: variable 'x' is uninitialized when used here kernel test robot
@ 2021-05-13 17:48 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2021-05-13 17:48 UTC (permalink / raw)
To: kernel test robot
Cc: kbuild-all, clang-built-linux, Linux Memory Management List
On Wed, May 12, 2021 at 07:38:22PM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head: ec85c95b0c90a17413901b018e8ade7b9eae7cad
> commit: 4b46fcb7f1a6a202e3f77ce377079b4243d1be6f [1888/2633] refscale: Add measurement of clock readout
> config: riscv-randconfig-r022-20210512 (attached as .config)
> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project a0fed635fe1701470062495a6ffee1c608f3f1bc)
> 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 riscv cross compiling tool for clang build
> # apt-get install binutils-riscv64-linux-gnu
> # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=4b46fcb7f1a6a202e3f77ce377079b4243d1be6f
> git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
> git fetch --no-tags linux-next master
> git checkout 4b46fcb7f1a6a202e3f77ce377079b4243d1be6f
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=riscv
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> kernel/rcu/refscale.c:479:3: warning: variable 'x' is uninitialized when used here [-Wuninitialized]
> x += ktime_get_real_fast_ns();
> ^
> kernel/rcu/refscale.c:474:7: note: initialize the variable 'x' to silence this warning
> u64 x;
> ^
> = 0
> kernel/rcu/refscale.c:492:3: warning: variable 'x' is uninitialized when used here [-Wuninitialized]
> x += ktime_get_real_fast_ns();
> ^
> kernel/rcu/refscale.c:487:7: note: initialize the variable 'x' to silence this warning
> u64 x;
> ^
> = 0
> 2 warnings generated.
>
> Kconfig warnings: (for reference only)
> WARNING: unmet direct dependencies detected for LOCKDEP
> Depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT && (FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86)
> Selected by
> - DEBUG_LOCK_ALLOC && DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
Fixed by updated commit 210b2a9a9247 ("refscale: Add measurement of
clock readout").
Thanx, Paul
> vim +/x +479 kernel/rcu/refscale.c
>
> 471
> 472 static void ref_clock_section(const int nloops)
> 473 {
> 474 u64 x;
> 475 int i;
> 476
> 477 preempt_disable();
> 478 for (i = nloops; i >= 0; i--) {
> > 479 x += ktime_get_real_fast_ns();
> 480 }
> 481 preempt_enable();
> 482 stopopts = x;
> 483 }
> 484
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-05-12 11:38 [linux-next:master 1888/2633] kernel/rcu/refscale.c:479:3: warning: variable 'x' is uninitialized when used here kernel test robot
2021-05-13 17:48 ` Paul E. McKenney
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