From 012c36be13521bd01118e9da0aece680c7fd62a9 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Fri, 6 Mar 2020 09:32:13 -0800
Subject: drm/edid: Distribute switch variables for initialization
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Git-commit: deec222e09a69d6d7b542c7367615bfad802c756
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Variables declared in a switch statement before any case statements
cannot be automatically initialized with compiler instrumentation (as
they are not part of any execution flow). With GCC's proposed automatic
stack variable initialization feature, this triggers a warning (and they
don't get initialized). Clang's automatic stack variable initialization
(via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also
doesn't initialize such variables[1]. Note that these warnings (or silent
skipping) happen before the dead-store elimination optimization phase,
so even when the automatic initializations are later elided in favor of
direct initializations, the warnings remain.
To avoid these problems, lift such variables up into the next code
block.
drivers/gpu/drm/drm_edid.c: In function ‘drm_edid_to_eld’:
drivers/gpu/drm/drm_edid.c:4395:9: warning: statement will never be
executed [-Wswitch-unreachable]
4395 | int sad_count;
| ^~~~~~~~~
[1] https://bugs.llvm.org/show_bug.cgi?id=44916
v2: move into function block instead being switch-local (Ville Syrjälä)
Signed-off-by: Kees Cook <keescook@chromium.org>
[danvet: keep the changelog]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/202003060930.DDCCB6659@keescook
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/drm_edid.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index b269cd7f7679..116451101426 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4434,6 +4434,7 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
if (cea_revision(cea) >= 3) {
int i, start, end;
+ int sad_count;
if (cea_db_offsets(cea, &start, &end)) {
start = 0;
@@ -4445,8 +4446,6 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
dbl = cea_db_payload_len(db);
switch (cea_db_tag(db)) {
- int sad_count;
-
case AUDIO_BLOCK:
/* Audio Data Block, contains SADs */
sad_count = min(dbl / 3, 15 - total_sad_count);
--
2.28.0