On Sun, Nov 01, 2020 at 10:06:04PM +0000, Matthew Wilcox wrote:
> 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?
How can sysfs_emit() be called on a non-page-aligned buffer? It's being
used on the buffer that was passed to the sysfs call.
And if you are writing multiple values to a single sysfs file output,
well, not good...
>
> +++ 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);
That's a bit too 'tricky' for my taste, why is it somehow needed?
thanks,
greg k-h
