FAILED: patch "[PATCH] drm/simpledrm: Fix return type of" failed to apply to 6.0-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.0-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Possible dependencies:

f9929f69de94 ("drm/simpledrm: Fix return type of simpledrm_simple_display_pipe_mode_valid()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f9929f69de94212f98b3ad72a3e81c3bd3d333e0 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@kernel.org>
Date: Mon, 25 Jul 2022 16:36:29 -0700
Subject: [PATCH] drm/simpledrm: Fix return type of
 simpledrm_simple_display_pipe_mode_valid()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When booting a kernel compiled with clang's CFI protection
(CONFIG_CFI_CLANG), there is a CFI failure in
drm_simple_kms_crtc_mode_valid() when trying to call
simpledrm_simple_display_pipe_mode_valid() through ->mode_valid():

[    0.322802] CFI failure (target: simpledrm_simple_display_pipe_mode_valid+0x0/0x8):
...
[    0.324928] Call trace:
[    0.324969]  __ubsan_handle_cfi_check_fail+0x58/0x60
[    0.325053]  __cfi_check_fail+0x3c/0x44
[    0.325120]  __cfi_slowpath_diag+0x178/0x200
[    0.325192]  drm_simple_kms_crtc_mode_valid+0x58/0x80
[    0.325279]  __drm_helper_update_and_validate+0x31c/0x464
...

The ->mode_valid() member in 'struct drm_simple_display_pipe_funcs'
expects a return type of 'enum drm_mode_status', not 'int'. Correct it
to fix the CFI failure.

Cc: stable@vger.kernel.org
Fixes: 11e8f5fd223b ("drm: Add simpledrm driver")
Link: https://github.com/ClangBuiltLinux/linux/issues/1647
Reported-by: Tomasz Paweł Gajc <tpgxyz@gmail.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220725233629.223223-1-nathan@kernel.org
(cherry picked from commit 0c09bc33aa8e9dc867300acaadc318c2f0d85a1e)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 768242a78e2b..5422363690e7 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -627,7 +627,7 @@ static const struct drm_connector_funcs simpledrm_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int
+static enum drm_mode_status
 simpledrm_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
 				    const struct drm_display_mode *mode)
 {