linux-kernel - [PATCH v7 22/25] dyndbg: improve err report in attach_user_module

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Message-ID: <20231012172137.3286566-23-jim.cromie@gmail.com>
Date:   Thu, 12 Oct 2023 11:21:33 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     linux-kernel@...r.kernel.org, jbaron@...mai.com,
        gregkh@...uxfoundation.org, dri-devel@...ts.freedesktop.org,
        amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org
Cc:     daniel.vetter@...ll.ch, jani.nikula@...el.com,
        ville.syrjala@...ux.intel.com, seanpaul@...omium.org,
        robdclark@...il.com, groeck@...gle.com, yanivt@...gle.com,
        bleung@...gle.com, linux-doc@...r.kernel.org,
        Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v7 22/25] dyndbg: improve err report in attach_user_module_classes

convert a WARN on 3 conditions, into BUG_ON 2 of them (which don't
happen), and an early return on (!cli->user_mod_name), which *was*
happening, so should be seen going forward.  Maybe this should be a
WARN.

NB: The underlying problem was a missing __align(8) in the
DYNDBG_CLASSMAP_USE, which manifested as a corrupt record with a map
pointer which segv'd.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 lib/dynamic_debug.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 974395bf8a83..3dc512fb1d66 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1284,9 +1284,11 @@ static void ddebug_attach_user_module_classes(struct ddebug_table *dt,
 	 */
 	for_each_boxed_vector(di, class_users, num_class_users, i, cli) {
 
-		if (WARN_ON(!cli || !cli->map || !cli->user_mod_name))
-			continue;
-
+		BUG_ON(!cli || !cli->map);
+		if (!cli->user_mod_name) {
+			pr_warn("class_ref[%d] !user-mod-name looking for %s\n", i, dt->mod_name);
+			return;
+		}
 		if (!strcmp(cli->user_mod_name, dt->mod_name)) {
 
 			vpr_cm_info(cli->map, "class_ref[%d] %s -> %s", i,
-- 
2.41.0