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SubjectRe: [PATCH 4/5] mm: shmem: Convert shmem_enabled_show to use sysfs_emit_at
On Sun, Nov 01, 2020 at 01:43:13PM -0800, Joe Perches wrote:
> > Why did you change this?
>
> Are you asking about the function argument alignment or the commit message?

The indentation. Don't change the fucking indentation, Joe.

> > Look, this isn't performance sensitive code. Just do something simple.
> >
> > if (shmem_huge == values[i])
> > buf += sysfs_emit(buf, "[%s]",
> > shmem_format_huge(values[i]));
> > else
> > buf += sysfs_emit(buf, "%s",
> > shmem_format_huge(values[i]));
> > if (i == ARRAY_SIZE(values) - 1)
> > buf += sysfs_emit(buf, "\n");
> > else
> > buf += sysfs_emit(buf, " ");
> >
> > Shame there's no sysfs_emitc, but there you go.
>
> I think what's there is simple.

Again, you're wrong.

> And your suggested code doesn't work.
> sysfs_emit is used for single emits.
> sysfs_emit_at is used for multiple emits.

Oh, ugh, sysfs_emit() should be able to work on a buffer that isn't
page aligned. Greg, how about this?

+++ b/fs/sysfs/file.c
@@ -722,13 +722,13 @@ int sysfs_emit(char *buf, const char *fmt, ...)
{
va_list args;
int len;
+ int start = offset_in_page(buf);

- if (WARN(!buf || offset_in_page(buf),
- "invalid sysfs_emit: buf:%p\n", buf))
+ if (WARN(!buf, "invalid sysfs_emit: buf:%p\n", buf))
return 0;

va_start(args, fmt);
- len = vscnprintf(buf, PAGE_SIZE, fmt, args);
+ len = vscnprintf(buf, PAGE_SIZE - start, fmt, args);
va_end(args);

return len;
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