mm: shmem: refactor thpsize_shmem_enabled_show() with helper arrays

Replace the hardcoded if/else chain of test_bit() calls and string
literals in thpsize_shmem_enabled_show() with a loop over
huge_shmem_orders_by_mode[] and huge_shmem_enabled_mode_strings[] arrays.

This makes thpsize_shmem_enabled_show() consistent with
thpsize_shmem_enabled_store() and eliminates duplicated mode name strings.

Link: https://lore.kernel.org/20260525102700.68707-3-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand (arm) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 748b135d04fb65f91c6d228ec1c92d9e6baccdbe..56c23a7b15c746666d14dba38c3224c1fd70eaec 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5490,20 +5490,30 @@ static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj,
                                          struct kobj_attribute *attr, char *buf)
 {
        int order = to_thpsize(kobj)->order;
-       const char *output;
-
-       if (test_bit(order, &huge_shmem_orders_always))
-               output = "[always] inherit within_size advise never";
-       else if (test_bit(order, &huge_shmem_orders_inherit))
-               output = "always [inherit] within_size advise never";
-       else if (test_bit(order, &huge_shmem_orders_within_size))
-               output = "always inherit [within_size] advise never";
-       else if (test_bit(order, &huge_shmem_orders_madvise))
-               output = "always inherit within_size [advise] never";
-       else
-               output = "always inherit within_size advise [never]";
+       int active = HUGE_SHMEM_ENABLED_NEVER;
+       int len = 0;
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(huge_mode_orders); i++) {
+               if (test_bit(order, huge_mode_orders[i])) {
+                       active = i;
+                       break;
+               }
+       }
+
+       for (i = 0; i < ARRAY_SIZE(huge_mode_strings); i++) {
+               if (i == active)
+                       len += sysfs_emit_at(buf, len, "[%s] ",
+                                            huge_mode_strings[i]);
+               else
+                       len += sysfs_emit_at(buf, len, "%s ",
+                                            huge_mode_strings[i]);
+       }
+
+       /* Replace trailing space with newline */
+       buf[len - 1] = '\n';
 
-       return sysfs_emit(buf, "%s\n", output);
+       return len;
 }
 
 static bool set_shmem_enabled_mode(int order, enum huge_mode mode)