Replace the hardcoded if/else chain of test_bit() calls and string
literals in defrag_show() with a loop over defrag_flags[] and
defrag_mode_strings[] arrays introduced in the previous commit.
This makes defrag_show() consistent with defrag_store() and eliminates
the duplicated mode name strings.
Signed-off-by: Breno Leitao <leitao@debian.org>
---
mm/huge_memory.c | 38 ++++++++++++++++++++++----------------
1 file changed, 22 insertions(+), 16 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4843e2154038f..eaa6623fa49e2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -447,24 +447,30 @@ static const enum transparent_hugepage_flag defrag_flags[] = {
static ssize_t defrag_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- const char *output;
+ int active = DEFRAG_NEVER;
+ int len = 0;
+ int i;
- if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
- &transparent_hugepage_flags))
- output = "[always] defer defer+madvise madvise never";
- else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
- &transparent_hugepage_flags))
- output = "always [defer] defer+madvise madvise never";
- else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
- &transparent_hugepage_flags))
- output = "always defer [defer+madvise] madvise never";
- else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
- &transparent_hugepage_flags))
- output = "always defer defer+madvise [madvise] never";
- else
- output = "always defer defer+madvise madvise [never]";
+ for (i = 0; i < ARRAY_SIZE(defrag_flags); i++) {
+ if (test_bit(defrag_flags[i], &transparent_hugepage_flags)) {
+ active = i;
+ break;
+ }
+ }
- return sysfs_emit(buf, "%s\n", output);
+ for (i = 0; i < ARRAY_SIZE(defrag_mode_strings); i++) {
+ if (i == active)
+ len += sysfs_emit_at(buf, len, "[%s] ",
+ defrag_mode_strings[i]);
+ else
+ len += sysfs_emit_at(buf, len, "%s ",
+ defrag_mode_strings[i]);
+ }
+
+ /* Replace trailing space with newline */
+ buf[len - 1] = '\n';
+
+ return len;
}
static ssize_t defrag_store(struct kobject *kobj,
--
2.52.0On Sat, Mar 21, 2026 at 12:06 AM Breno Leitao <leitao@debian.org> wrote:
>
> Replace the hardcoded if/else chain of test_bit() calls and string
> literals in defrag_show() with a loop over defrag_flags[] and
> defrag_mode_strings[] arrays introduced in the previous commit.
>
> This makes defrag_show() consistent with defrag_store() and eliminates
> the duplicated mode name strings.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
> mm/huge_memory.c | 38 ++++++++++++++++++++++----------------
> 1 file changed, 22 insertions(+), 16 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4843e2154038f..eaa6623fa49e2 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -447,24 +447,30 @@ static const enum transparent_hugepage_flag defrag_flags[] = {
> static ssize_t defrag_show(struct kobject *kobj,
> struct kobj_attribute *attr, char *buf)
> {
> - const char *output;
> + int active = DEFRAG_NEVER;
> + int len = 0;
> + int i;
>
> - if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
> - &transparent_hugepage_flags))
> - output = "[always] defer defer+madvise madvise never";
> - else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
> - &transparent_hugepage_flags))
> - output = "always [defer] defer+madvise madvise never";
> - else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
> - &transparent_hugepage_flags))
> - output = "always defer [defer+madvise] madvise never";
> - else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
> - &transparent_hugepage_flags))
> - output = "always defer defer+madvise [madvise] never";
> - else
> - output = "always defer defer+madvise madvise [never]";
> + for (i = 0; i < ARRAY_SIZE(defrag_flags); i++) {
> + if (test_bit(defrag_flags[i], &transparent_hugepage_flags)) {
> + active = i;
> + break;
> + }
> + }
>
> - return sysfs_emit(buf, "%s\n", output);
> + for (i = 0; i < ARRAY_SIZE(defrag_mode_strings); i++) {
> + if (i == active)
> + len += sysfs_emit_at(buf, len, "[%s] ",
> + defrag_mode_strings[i]);
> + else
> + len += sysfs_emit_at(buf, len, "%s ",
> + defrag_mode_strings[i]);
> + }
> +
> + /* Replace trailing space with newline */
> + buf[len - 1] = '\n';
> +
Interesting. We used to use sysfs_emit(buf, "%s\n", output),
which appends a newline automatically. Now you’re replacing
the final ' ' with '\n'.
LGTM,
Reviewed-by: Barry Song <baohua@kernel.org>
On 2026/3/21 00:05, Breno Leitao wrote: > Replace the hardcoded if/else chain of test_bit() calls and string > literals in defrag_show() with a loop over defrag_flags[] and > defrag_mode_strings[] arrays introduced in the previous commit. > > This makes defrag_show() consistent with defrag_store() and eliminates > the duplicated mode name strings. > > Signed-off-by: Breno Leitao <leitao@debian.org> > --- LGTM. Tested-by: Lance Yang <lance.yang@linux.dev> And also, Reviewed-by: Lance Yang <lance.yang@linux.dev>
On 3/20/26 17:05, Breno Leitao wrote:
> Replace the hardcoded if/else chain of test_bit() calls and string
> literals in defrag_show() with a loop over defrag_flags[] and
> defrag_mode_strings[] arrays introduced in the previous commit.
>
> This makes defrag_show() consistent with defrag_store() and eliminates
> the duplicated mode name strings.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
> mm/huge_memory.c | 38 ++++++++++++++++++++++----------------
> 1 file changed, 22 insertions(+), 16 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4843e2154038f..eaa6623fa49e2 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -447,24 +447,30 @@ static const enum transparent_hugepage_flag defrag_flags[] = {
> static ssize_t defrag_show(struct kobject *kobj,
> struct kobj_attribute *attr, char *buf)
> {
> - const char *output;
> + int active = DEFRAG_NEVER;
> + int len = 0;
> + int i;
>
> - if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
> - &transparent_hugepage_flags))
> - output = "[always] defer defer+madvise madvise never";
> - else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
> - &transparent_hugepage_flags))
> - output = "always [defer] defer+madvise madvise never";
> - else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
> - &transparent_hugepage_flags))
> - output = "always defer [defer+madvise] madvise never";
> - else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
> - &transparent_hugepage_flags))
> - output = "always defer defer+madvise [madvise] never";
> - else
> - output = "always defer defer+madvise madvise [never]";
> + for (i = 0; i < ARRAY_SIZE(defrag_flags); i++) {
> + if (test_bit(defrag_flags[i], &transparent_hugepage_flags)) {
> + active = i;
> + break;
> + }
> + }
>
> - return sysfs_emit(buf, "%s\n", output);
> + for (i = 0; i < ARRAY_SIZE(defrag_mode_strings); i++) {
> + if (i == active)
> + len += sysfs_emit_at(buf, len, "[%s] ",
> + defrag_mode_strings[i]);
> + else
> + len += sysfs_emit_at(buf, len, "%s ",
> + defrag_mode_strings[i]);
> + }
> +
> + /* Replace trailing space with newline */
> + buf[len - 1] = '\n';
> +
> + return len;
The old code was certainly way easier to get. But this one here looks
good to me.
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
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