11:48 p.m.
On Tue 2021-06-08 10:43:46, kernel test robot wrote:
Hi John,
I love your patch! Perhaps something to improve:
[auto build test WARNING on next-20210607]
url:
https://github.com/0day-ci/linux/commits/John-Ogness/introduce-printk-cpu...
base: 7f09e895a7f3e0af63bf9ec6c7c22893ec7e6c8e
config: mips-randconfig-r036-20210607 (attached as .config)
compiler: mips-linux-gcc (GCC) 9.3.0
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
#
https://github.com/0day-ci/linux/commit/136bcc2980e636b2ae156ca63fbe95c71...
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review
John-Ogness/introduce-printk-cpu-lock/20210608-040454
git checkout 136bcc2980e636b2ae156ca63fbe95c713e44c1b
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp(a)intel.com>
All warnings (new ones prefixed by >>):
lib/dump_stack.c: In function 'dump_stack_lvl':
>> lib/dump_stack.c:107:2: warning: 'lock_flag' is used uninitialized in
this function [-Wuninitialized]
107 | printk_cpu_unlock_irqrestore(lock_flag, irq_flags);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Interesting. I am curious that it does not complain also about
irq_flags. But it is possible the it reports only the first problem.
Anyway, we will likely need to do some trickery via #define to tell
the compiler that the value is set. I mean to do similar thing as:
#define raw_local_irq_save(flags) \
do { \
typecheck(unsigned long, flags); \
flags = arch_local_irq_save(); \
} while (0)
In our case, it might look like:
#define printk_cpu_lock_irqsave(lock_nested, irq_flags) \
do { \
local_irq_save(irq_flags); \
typecheck(bool, lock_nested); \
lock_nested = __printk_cpu_lock(irq_flags); \
} while (0)
then we would need to do in __prink_cpu_lock(unsigned long irq_flags)
} else {
local_irq_restore(irq_flags);
/*
* Wait for the lock to release before jumping to cmpxchg()
* in order to mitigate the thundering herd problem.
*/
do {
cpu_relax();
} while (atomic_read(&printk_cpulock_owner) != -1);
local_irq_save(irq_flags)
goto retry;
}
Best Regards,
Petr