linux-kernel - [PATCH] mei: late_bind: Fix -Wincompatible-function-pointer-types-strict

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Message-Id: <20250920-drm-xe-fix-wifpts-v1-1-c89b5357c7ba@kernel.org>
Date: Sat, 20 Sep 2025 16:17:50 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Lucas De Marchi <lucas.demarchi@...el.com>, 
 Rodrigo Vivi <rodrigo.vivi@...el.com>, 
 Alexander Usyskin <alexander.usyskin@...el.com>, 
 Anshuman Gupta <anshuman.gupta@...el.com>, 
 Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: Arnd Bergmann <arnd@...db.de>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 intel-xe@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] mei: late_bind: Fix
 -Wincompatible-function-pointer-types-strict

When building with -Wincompatible-function-pointer-types-strict, a
warning designed to catch kernel control flow integrity (kCFI) issues at
build time, there is an instance in the new mei late binding code
originating from the type parameter of mei_lb_push_payload():

  drivers/misc/mei/mei_lb.c:211:18: error: incompatible function pointer types initializing 'int (*)(struct device *, u32, u32, const void *, size_t)' (aka 'int (*)(struct device *, unsigned int, unsigned int, const void *, unsigned long)') with an expression of type 'int (struct device *, enum intel_lb_type, u32, const void *, size_t)' (aka 'int (struct device *, enum intel_lb_type, unsigned int, const void *, unsigned long)') [-Werror,-Wincompatible-function-pointer-types-strict]
    211 |         .push_payload = mei_lb_push_payload,
        |                         ^~~~~~~~~~~~~~~~~~~

While 'unsigned int' and 'enum intel_lb_type' are ABI compatible, hence
no regular warning from -Wincompatible-function-pointer-types, the
mismatch will trigger a kCFI violation when mei_lb_push_payload() is
called indirectly.

Update the type parameter of mei_lb_push_payload() to be 'u32' to match
the prototype in 'struct intel_lb_component_ops', clearing up the
warning and kCFI violation.

Fixes: 741eeabb7c78 ("mei: late_bind: add late binding component driver")
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 drivers/misc/mei/mei_lb.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/misc/mei/mei_lb.c b/drivers/misc/mei/mei_lb.c
index 77686b108d3c..78717ee8ac9a 100644
--- a/drivers/misc/mei/mei_lb.c
+++ b/drivers/misc/mei/mei_lb.c
@@ -134,8 +134,7 @@ static bool mei_lb_check_response(const struct device *dev, ssize_t bytes,
 	return true;
 }
 
-static int mei_lb_push_payload(struct device *dev,
-			       enum intel_lb_type type, u32 flags,
+static int mei_lb_push_payload(struct device *dev, u32 type, u32 flags,
 			       const void *payload, size_t payload_size)
 {
 	struct mei_cl_device *cldev;

---
base-commit: d9b2623319fa20c2206754284291817488329648
change-id: 20250920-drm-xe-fix-wifpts-58fd1be433d4

Best regards,
--  
Nathan Chancellor <nathan@...nel.org>