From deec222e09a69d6d7b542c7367615bfad802c756 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 6 Mar 2020 09:32:13 -0800 Subject: [PATCH] drm/edid: Distribute switch variables for initialization MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 [danvet: keep the changelog] Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/202003060930.DDCCB6659@keescook --- 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); -- 2.39.5