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mm: shmem: convert shmem_enabled_show to use sysfs_emit_at 

Update the function to use sysfs_emit_at while neatening the uses of
sprintf and overwriting the last space char with a newline to avoid
possible output buffer overflow.

Miscellanea:

 - in shmem_enabled_show, the removal of the indirected use of fmt
   allows __printf verification

Link: https://lkml.kernel.org/r/b612a93825e5ea330cb68d2e8b516e9687a06cc6.1605376435.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joe Perches 2020-12-14 19:14:53 -08:00 committed by Linus Torvalds
parent 5e4c0d86cf
commit 79d4d38a03
1 changed files with 12 additions and 9 deletions
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21
mm/shmem.c
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@ -4020,7 +4020,7 @@ 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,
@ -4030,16 +4030,19 @@ static ssize_t shmem_enabled_show(struct kobject *kobj,
SHMEM_HUGE_DENY,
SHMEM_HUGE_FORCE,
};
int i, count;
int len = 0;
int i;
for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
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]));
}
buf[count - 1] = '\n';
return count;
len += sysfs_emit_at(buf, len, "\n");
return len;
}
static ssize_t shmem_enabled_store(struct kobject *kobj,