From: Joe Perches <joe@perches.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/5] mm: shmem: Convert shmem_enabled_show to use sysfs_emit_at
Date: Sun, 01 Nov 2020 13:04:35 -0800 [thread overview]
Message-ID: <616b92af9378e9f9697555074bba1e377450477f.camel@perches.com> (raw)
In-Reply-To: <20201101204834.GF27442@casper.infradead.org>
On Sun, 2020-11-01 at 20:48 +0000, Matthew Wilcox wrote:
> On Sun, Nov 01, 2020 at 12:12:51PM -0800, Joe Perches wrote:
> > @@ -4024,7 +4024,7 @@ int __init shmem_init(void)
> >
> >
> > #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
> > static ssize_t shmem_enabled_show(struct kobject *kobj,
> > - struct kobj_attribute *attr, char *buf)
> > + struct kobj_attribute *attr, char *buf)
> > {
> > static const int values[] = {
> > SHMEM_HUGE_ALWAYS,
>
> Why?
why what?
> > @@ -4034,16 +4034,19 @@ static ssize_t shmem_enabled_show(struct kobject *kobj,
> > SHMEM_HUGE_DENY,
> > SHMEM_HUGE_FORCE,
> > };
> > - int i, count;
> > -
> > - for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
> > - const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
> > + int len = 0;
> > + int i;
>
> Better:
> int i, len = 0;
I generally disagree as I think it better to have each declaration on an
individual line.
> > - count += sprintf(buf + count, fmt,
> > - shmem_format_huge(values[i]));
> > + for (i = 0; i < ARRAY_SIZE(values); i++) {
> > + len += sysfs_emit_at(buf, len,
> > + shmem_huge == values[i] ? "%s[%s]" : "%s%s",
> > + i ? " " : "",
> > + shmem_format_huge(values[i]));
>
> This is ... complicated. I thought the point of doing all the sysfs_emit
> stuff was to simplify things.
The removal of fmt allows the format and argument to be __printf verified.
Indirected formats do not generally allow that.
And using sysfs_emit is not really intended to simplify output code, it's
used to make sure there isn't a overflow of the PAGE_SIZE output buf when
using sprintf/snprintf.
next prev parent reply other threads:[~2020-11-01 21:04 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-01 20:12 [PATCH 0/5] mm: Convert sysfs sprintf family to sysfs_emit Joe Perches
2020-11-01 20:12 ` [PATCH 1/5] mm: Use sysfs_emit for struct kobject * uses Joe Perches
2020-11-01 20:12 ` [PATCH 2/5] mm: huge_memory: Convert remaining use of sprintf to sysfs_emit and neatening Joe Perches
2020-11-01 20:12 ` [PATCH 3/5] mm:backing-dev: Use sysfs_emit in macro defining functions Joe Perches
2020-11-01 20:12 ` [PATCH 4/5] mm: shmem: Convert shmem_enabled_show to use sysfs_emit_at Joe Perches
2020-11-01 20:48 ` Matthew Wilcox
2020-11-01 21:04 ` Joe Perches [this message]
2020-11-01 21:19 ` Matthew Wilcox
2020-11-01 21:43 ` Joe Perches
2020-11-01 22:06 ` Matthew Wilcox
2020-11-01 22:08 ` Joe Perches
2020-11-01 22:13 ` Joe Perches
2020-11-01 22:14 ` Joe Perches
2020-11-02 13:33 ` Greg Kroah-Hartman
2020-11-02 14:08 ` Matthew Wilcox
2020-11-02 14:32 ` Greg Kroah-Hartman
2020-11-02 14:40 ` Matthew Wilcox
2020-11-02 17:01 ` Joe Perches
2020-11-01 20:12 ` [PATCH 5/5] mm: slub: Convert sysfs sprintf family to sysfs_emit/sysfs_emit_at Joe Perches
2020-11-13 12:10 ` [mm] b6efe2fcc4: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2020-11-13 16:13 ` Joe Perches
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