* Re: [RFC PATCH v3 1/1] trace,smp: Add tracepoints around remotelly called functions
2023-05-11 0:46 ` [RFC PATCH v3 1/1] trace,smp: Add tracepoints around remotelly called functions kernel test robot
@ 2023-05-11 5:13 ` Leonardo Brás
0 siblings, 0 replies; 2+ messages in thread
From: Leonardo Brás @ 2023-05-11 5:13 UTC (permalink / raw)
To: kernel test robot; +Cc: llvm, oe-kbuild-all
On Thu, 2023-05-11 at 08:46 +0800, kernel test robot wrote:
> Hi Leonardo,
>
> [This is a private test report for your RFC patch.]
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on linus/master]
> [also build test WARNING on v6.4-rc1 next-20230510]
> [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#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Leonardo-Bras/trace-smp-Add-tracepoints-around-remotelly-called-functions/20230511-070554
> base: linus/master
> patch link: https://lore.kernel.org/r/20230510230128.150384-1-leobras%40redhat.com
> patch subject: [RFC PATCH v3 1/1] trace,smp: Add tracepoints around remotelly called functions
> config: riscv-buildonly-randconfig-r004-20230509 (https://download.01.org/0day-ci/archive/20230511/202305110816.mcNeYnWd-lkp@intel.com/config)
> compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project b0fb98227c90adf2536c9ad644a74d5e92961111)
> 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://github.com/intel-lab-lkp/linux/commit/fcef1c202a1635b9c7244f06bbad605562b83d43
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Leonardo-Bras/trace-smp-Add-tracepoints-around-remotelly-called-functions/20230511-070554
> git checkout fcef1c202a1635b9c7244f06bbad605562b83d43
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> > Reported-by: kernel test robot <lkp@intel.com>
> > Link: https://lore.kernel.org/oe-kbuild-all/202305110816.mcNeYnWd-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> > > kernel/smp.c:389:27: warning: passing 8-byte aligned argument to 32-byte aligned parameter 3 of 'csd_do_func' may result in an unaligned pointer access [-Walign-mismatch]
> csd_do_func(func, info, csd);
> ^
> 1 warning generated.
Oh, ok, it makes sense.
On generic_exec_single(), the second parameter is a struct __call_single_data,
while csd_do_func() csd argument is a call_single_data_t.
In smp.h we have:
/* Use __aligned() to avoid to use 2 cache lines for 1 csd */
typedef struct __call_single_data call_single_data_t
__aligned(sizeof(struct __call_single_data));
Which makes call_single_data_t 32-byte aligned, while struct __call_single_data
is 8-byte aligned in 64BIT.
Changing like this should fix the warning:
-csd_do_func(smp_call_func_t func, void *info, call_single_data_t *csd)
+csd_do_func(smp_call_func_t func, void *info, struct __call_single_data *csd)
I will send this on v4 shortly.
>
>
> vim +/csd_do_func +389 kernel/smp.c
>
> 369
> 370 /*
> 371 * Insert a previously allocated call_single_data_t element
> 372 * for execution on the given CPU. data must already have
> 373 * ->func, ->info, and ->flags set.
> 374 */
> 375 static int generic_exec_single(int cpu, struct __call_single_data *csd)
> 376 {
> 377 if (cpu == smp_processor_id()) {
> 378 smp_call_func_t func = csd->func;
> 379 void *info = csd->info;
> 380 unsigned long flags;
> 381
> 382 /*
> 383 * We can unlock early even for the synchronous on-stack case,
> 384 * since we're doing this from the same CPU..
> 385 */
> 386 csd_lock_record(csd);
> 387 csd_unlock(csd);
> 388 local_irq_save(flags);
> > 389 csd_do_func(func, info, csd);
> 390 csd_lock_record(NULL);
> 391 local_irq_restore(flags);
> 392 return 0;
> 393 }
> 394
> 395 if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
> 396 csd_unlock(csd);
> 397 return -ENXIO;
> 398 }
> 399
> 400 __smp_call_single_queue(cpu, &csd->node.llist);
> 401
> 402 return 0;
> 403 }
> 404
>
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