[PATCH 3/4] RAS/amd/fmpm: Make max_nr_entries read-only

["Rui Qi" <qirui.001@bytedance.com>]

max_nr_entries is used during module init to calculate max_rec_len.
That length determines the size of each allocated FRU record and is not
resized after init.

Leaving the parameter writable lets a later sysfs write raise the runtime
limit used by update_fru_record(), allowing entries beyond the allocated
flexible array to be written.

Expose the parameter as read-only so it can still be set at module load
time, but cannot diverge from the allocation size afterwards.

Fixes: 6f15e617cc99 ("RAS: Introduce a FRU memory poison manager")
Signed-off-by: Rui Qi <qirui.001@bytedance.com>
---
 drivers/ras/amd/fmpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ras/amd/fmpm.c b/drivers/ras/amd/fmpm.c
index 0231163e2634..14a103de9d62 100644
--- a/drivers/ras/amd/fmpm.c
+++ b/drivers/ras/amd/fmpm.c
@@ -138,7 +138,7 @@ static struct dentry *fmpm_dfs_entries;
  * No input or '0' will default to FMPM_DEFAULT_MAX_NR_ENTRIES.
  */
 static u8 max_nr_entries;
-module_param(max_nr_entries, byte, 0644);
+module_param(max_nr_entries, byte, 0444);
 MODULE_PARM_DESC(max_nr_entries,
 		 "Maximum number of memory poison descriptor entries per FRU");
 
-- 
2.20.1