From 1b3da8ffaa158e9a95c19b17c14d7259d58bc0cd Mon Sep 17 00:00:00 2001
From: Nathan Lynch <nathanl@linux.ibm.com>
Date: Thu, 27 Jun 2019 00:15:36 -0500
Subject: [PATCH] powerpc/cacheinfo: Improve diagnostics about malformed cache
 lists

References: jsc#SLE-13615 bsc#1180100 ltc#190257 git-fixes
Patch-mainline: v5.9-rc1
Git-commit: 1b3da8ffaa158e9a95c19b17c14d7259d58bc0cd

If we have a bug which causes us to start with the wrong kind of OF
node when linking up the cache tree, it's helpful for debugging to
print information about what we found vs what we expected. So replace
uses of WARN_ON_ONCE with WARN_ONCE, which lets us include an
informative message instead of a contentless backtrace.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190627051537.7298-4-nathanl@linux.ibm.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/kernel/cacheinfo.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/cacheinfo.c b/arch/powerpc/kernel/cacheinfo.c
index 879154c839f3..a116d5bb6b12 100644
--- a/arch/powerpc/kernel/cacheinfo.c
+++ b/arch/powerpc/kernel/cacheinfo.c
@@ -424,8 +424,14 @@ static void link_cache_lists(struct cache *smaller, struct cache *bigger)
 
 static void do_subsidiary_caches_debugcheck(struct cache *cache)
 {
-	WARN_ON_ONCE(cache->level != 1);
-	WARN_ON_ONCE(!of_node_is_type(cache->ofnode, "cpu"));
+	WARN_ONCE(cache->level != 1,
+		  "instantiating cache chain from L%d %s cache for "
+		  "%pOFP instead of an L1\n", cache->level,
+		  cache_type_string(cache), cache->ofnode);
+	WARN_ONCE(!of_node_is_type(cache->ofnode, "cpu"),
+		  "instantiating cache chain from node %pOFP of type '%s' "
+		  "instead of a cpu node\n", cache->ofnode,
+		  of_node_get_device_type(cache->ofnode));
 }
 
 static void do_subsidiary_caches(struct cache *cache)
-- 
2.31.1