RAS/CEC: Check count_threshold unconditionally

The count_threshold should be checked unconditionally, after insertion
too, so that a count_threshold value of 1 can cause an immediate
offlining. I.e., offline the page on the *first* error encountered.

Add comments to make it clear what cec_add_elem() does, while at it.

Reported-by: WANG Chao <chao.wang@ucloud.cn>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac@vger.kernel.org
Link: https://lkml.kernel.org/r/20190418034115.75954-3-chao.wang@ucloud.cn

1 files changed, 10 insertions, 17 deletions

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index f5795adc5a6e..73a975c26f9f 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -294,6 +294,7 @@ int cec_add_elem(u64 pfn)
 
         ca->ces_entered++;
 
+        /* Array full, free the LRU slot. */
         if (ca->n == MAX_ELEMS)
                 WARN_ON(!del_lru_elem_unlocked(ca));
 
@@ -306,24 +307,17 @@ int cec_add_elem(u64 pfn)
                         (void *)&ca->array[to],
                         (ca->n - to) * sizeof(u64));
 
-                ca->array[to] = (pfn << PAGE_SHIFT) |
-                                (DECAY_MASK << COUNT_BITS) | 1;
-
+                ca->array[to] = pfn << PAGE_SHIFT;
                 ca->n++;
-
-                ret = 0;
-
-                goto decay;
         }
 
-        count = COUNT(ca->array[to]);
-
-        if (count < count_threshold) {
-                ca->array[to] |= (DECAY_MASK << COUNT_BITS);
-                ca->array[to]++;
+        /* Add/refresh element generation and increment count */
+        ca->array[to] |= DECAY_MASK << COUNT_BITS;
+        ca->array[to]++;
 
-                ret = 0;
-        } else {
+        /* Check action threshold and soft-offline, if reached. */
+        count = COUNT(ca->array[to]);
+        if (count >= count_threshold) {
                 u64 pfn = ca->array[to] >> PAGE_SHIFT;
 
                 if (!pfn_valid(pfn)) {
@@ -338,15 +332,14 @@ int cec_add_elem(u64 pfn)
                 del_elem(ca, to);
 
                 /*
-                 * Return a >0 value to denote that we've reached the offlining
-                 * threshold.
+                 * Return a >0 value to callers, to denote that we've reached
+                 * the offlining threshold.
                  */
                 ret = 1;
 
                 goto unlock;
         }
 
-decay:
         ca->decay_count++;
 
         if (ca->decay_count >= CLEAN_ELEMS)