linux-kernel - [PATCH v2] RAS/CEC: Memory Corrected Errors consistent event filtering

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Message-Id: <1617722939-29670-1-git-send-email-william.roche@oracle.com>
Date:   Tue,  6 Apr 2021 11:28:59 -0400
From:   “William Roche <william.roche@...cle.com>
To:     bp@...en8.de
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony.luck@...el.com, william.roche@...cle.com
Subject: [PATCH v2] RAS/CEC: Memory Corrected Errors consistent event filtering

From: William Roche <william.roche@...cle.com>

The Corrected Error events collected by the cec_add_elem() have to be
consistently filtered out.
We fix the case where the value of find_elem() to find the slot of a pfn
was mistakenly used as the return value of the function.
Now the MCE notifiers chain relying on MCE_HANDLED_CEC would only report
filtered corrected errors that reached the action threshold.

Signed-off-by: William Roche <william.roche@...cle.com>
---

Notes:
    This is the new patch version using an additional 'err' variable.
    Unit tested it on a VM instance and a "Bare Metal" machine.
    
    No reporting is done by the MCE_HANDLED_CEC aware notifiers until
    the action threshold is reached.

 drivers/ras/cec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index ddecf25..b926c67 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -312,8 +312,8 @@ static bool sanity_check(struct ce_array *ca)
 static int cec_add_elem(u64 pfn)
 {
 	struct ce_array *ca = &ce_arr;
+	int count, err, ret = 0;
 	unsigned int to = 0;
-	int count, ret = 0;
 
 	/*
 	 * We can be called very early on the identify_cpu() path where we are
@@ -330,8 +330,8 @@ static int cec_add_elem(u64 pfn)
 	if (ca->n == MAX_ELEMS)
 		WARN_ON(!del_lru_elem_unlocked(ca));
 
-	ret = find_elem(ca, pfn, &to);
-	if (ret < 0) {
+	err = find_elem(ca, pfn, &to);
+	if (err < 0) {
 		/*
 		 * Shift range [to-end] to make room for one more element.
 		 */
-- 
1.8.3.1