On Thu, 25 Apr 2019, Li, Aubrey wrote: > On 2019/4/25 5:18, Thomas Gleixner wrote: > > On Mon, 22 Apr 2019, Aubrey Li wrote: > >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > >> index 5ad92419be19..d5a9c5ddd453 100644 > >> --- a/arch/x86/Kconfig > >> +++ b/arch/x86/Kconfig > >> @@ -208,6 +208,7 @@ config X86 > >> select USER_STACKTRACE_SUPPORT > >> select VIRT_TO_BUS > >> select X86_FEATURE_NAMES if PROC_FS > >> + select PROC_PID_ARCH_STATUS if PROC_FS > > > > Can you please stop mixing arch and proc code? There is no point in > > enabling this on x86 right away. > > > >> + > >> +config PROC_PID_ARCH_STATUS > >> + bool "Enable /proc/<pid>/arch_status file" > > > > Why is this switchable? x86 selects it if PROC_FS is enabled and all other > > architectures are absolutely not interested in this. > > Above and this, I was trying to avoid an empty arch_file on other architectures. > In previous proposal the entry only exists on the platform with AVX512. What's the benefit of having a conditional enabled empty file for all other architectures? Nothing AFAICT. > >> +/* > >> + * Add support for task architecture specific output in /proc/pid/arch_status. > >> + * task_arch_status() must be defined in asm/processor.h > >> + */ > >> +#ifdef CONFIG_PROC_PID_ARCH_STATUS > >> +# ifndef task_arch_status > >> +# define task_arch_status(m, task) > >> +# endif > > > > What exactly is the point of this macro mess? If an architecture selects > > CONFIG_PROC_PID_ARCH_STATUS then it has to provide proc_task_arch_status() > > and the prototype should be in include/linux/proc_fs.h. > > I was trying to address Andy's last comments. If we have the prototype in > include/linux/proc_fs.h, we'll have a weak function definition in fs/proc/array.c, > which bloats other architectures. > > In that way proc_task_arch_status() should be defined in asm/processor.h, > but proc_task_arch_status() has four parameters, I don't want unnecessary > "struct pid_namespace *ns" and "struct pid *pid" leaked into arch headers, > so I defined task_arch_status(m, task) to avoid that. This #define mess is ugly and pointless. Let the arch select CONFIG_PROC_PID_ARCH_STATUS and if it selects it it has to provide the function. No waek function required at all. Thanks, tglx
