[tip:ras/core] RAS/CEC: Sanity-check array on every insertion

[tip-bot for Borislav Petkov]

Commit-ID:  9632a3299bb1897f01c6a485ff035b20e61d7ae1
Gitweb:     https://git.kernel.org/tip/9632a3299bb1897f01c6a485ff035b20e61d7ae1
Author:     Borislav Petkov <bp@xxxxxxx>
AuthorDate: Sun, 21 Apr 2019 21:41:45 +0200
Committer:  Borislav Petkov <bp@xxxxxxx>
CommitDate: Sat, 8 Jun 2019 17:35:34 +0200

RAS/CEC: Sanity-check array on every insertion

Check the elements order in the array after every insertion.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
---
 drivers/ras/cec.c | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index f57e869dfea2..da5797c38051 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -276,11 +276,39 @@ static u64 __maybe_unused del_lru_elem(void)
 	return pfn;
 }
 
+static bool sanity_check(struct ce_array *ca)
+{
+	bool ret = false;
+	u64 prev = 0;
+	int i;
+
+	for (i = 0; i < ca->n; i++) {
+		u64 this = PFN(ca->array[i]);
+
+		if (WARN(prev > this, "prev: 0x%016llx <-> this: 0x%016llx\n", prev, this))
+			ret = true;
+
+		prev = this;
+	}
+
+	if (!ret)
+		return ret;
+
+	pr_info("Sanity check dump:\n{ n: %d\n", ca->n);
+	for (i = 0; i < ca->n; i++) {
+		u64 this = PFN(ca->array[i]);
+
+		pr_info(" %03d: [%016llx|%03llx]\n", i, this, FULL_COUNT(ca->array[i]));
+	}
+	pr_info("}\n");
+
+	return ret;
+}
 
 int cec_add_elem(u64 pfn)
 {
 	struct ce_array *ca = &ce_arr;
-	unsigned int to;
+	unsigned int to = 0;
 	int count, ret = 0;
 
 	/*
@@ -345,6 +373,8 @@ int cec_add_elem(u64 pfn)
 	if (ca->decay_count >= CLEAN_ELEMS)
 		do_spring_cleaning(ca);
 
+	WARN_ON_ONCE(sanity_check(ca));
+
 unlock:
 	mutex_unlock(&ce_mutex);
 
@@ -402,7 +432,6 @@ DEFINE_DEBUGFS_ATTRIBUTE(count_threshold_ops, u64_get, count_threshold_set, "%ll
 static int array_dump(struct seq_file *m, void *v)
 {
 	struct ce_array *ca = &ce_arr;
-	u64 prev = 0;
 	int i;
 
 	mutex_lock(&ce_mutex);
@@ -412,10 +441,6 @@ static int array_dump(struct seq_file *m, void *v)
 		u64 this = PFN(ca->array[i]);
 
 		seq_printf(m, " %03d: [%016llx|%03llx]\n", i, this, FULL_COUNT(ca->array[i]));
-
-		WARN_ON(prev > this);
-
-		prev = this;
 	}
 
 	seq_printf(m, "}\n");