Re: [PATCH v14 1/3] /proc/pid/status: Add support for architecture specific output

[Andy Lutomirski]

On Tue, Apr 9, 2019 at 7:20 PM Li, Aubrey <aubrey.li@xxxxxxxxxxxxxxx> wrote:
>
> On 2019/4/10 9:58, Andy Lutomirski wrote:
> > On Tue, Apr 9, 2019 at 6:55 PM Aubrey Li <aubrey.li@xxxxxxxxxxxxxxx> wrote:
> >>
> >> The architecture specific information of the running processes could
> >> be useful to the userland. Add support to examine process architecture
> >> specific information externally.
> >>
> >> Signed-off-by: Aubrey Li <aubrey.li@xxxxxxxxxxxxxxx>
> >> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> >> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> >> Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> >> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> >> Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> >> Cc: Linux API <linux-api@xxxxxxxxxxxxxxx>
> >> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
> >> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> >> ---
> >>  fs/proc/array.c         | 5 +++++
> >>  include/linux/proc_fs.h | 2 ++
> >>  2 files changed, 7 insertions(+)
> >>
> >> diff --git a/fs/proc/array.c b/fs/proc/array.c
> >> index 2edbb657f859..331592a61718 100644
> >> --- a/fs/proc/array.c
> >> +++ b/fs/proc/array.c
> >> @@ -401,6 +401,10 @@ static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm)
> >>         seq_printf(m, "THP_enabled:\t%d\n", thp_enabled);
> >>  }
> >>
> >> +void __weak arch_proc_pid_status(struct seq_file *m, struct task_struct *task)
> >> +{
> >> +}
> >
> > This pointlessly bloats other architectures.  Do this instead in an
> > appropriate header:
> >
> > #ifndef arch_proc_pid_status
> > static inline void arch_proc_pid_status(...)
> > {
> > }
> > #endif
> >
>
> I saw a bunch of similar weak functions, is it not acceptable?
>
> fs/proc$ grep weak *.c
> cpuinfo.c:__weak void arch_freq_prepare_all(void)
> meminfo.c:void __attribute__((weak)) arch_report_meminfo(struct seq_file *m)
> vmcore.c:int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
> vmcore.c:void __weak elfcorehdr_free(unsigned long long addr)
> vmcore.c:ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
> vmcore.c:ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
> vmcore.c:int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
> vmcore.c:ssize_t __weak

I think they're acceptable, but I don't personally like them.

>
> > Or add /proc/PID/x86_status, which sounds better in most respects to me.
> >
>
> I didn't figure out how to make /proc/PID/x86_status invisible to other
> architectures in an appropriate way, do you have any suggestions?

#ifdef CONFIG_X86?