linux-kernel - [PATCH v1 1/1] platform/x86: ideapad-laptop: Make the scope

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Message-ID: <20240829165105.1609180-1-andriy.shevchenko@linux.intel.com>
Date: Thu, 29 Aug 2024 19:50:32 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Gergo Koteles <soyer@....hu>,
	Hans de Goede <hdegoede@...hat.com>,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Ike Panhc <ike.pan@...onical.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	kernel test robot <lkp@...el.com>
Subject: [PATCH v1 1/1] platform/x86: ideapad-laptop: Make the scope_guard() clear of its scope

First of all, it's a bit counterintuitive to have something like

	int err;
	...
	scoped_guard(...)
		err = foo(...);
	if (err)
		return err;

Second, with a particular kernel configuration and compiler version in
one of such cases the objtool is not happy:

  ideapad-laptop.o: warning: objtool: .text.fan_mode_show: unexpected end of section

I'm not an expert on all this, but the theory is that compiler and
linker in this case can't understand that 'result' variable will be
always initialized as long as no error has been returned. Assigning
'result' to a dummy value helps with this. Note, that fixing the
scoped_guard() scope (as per above) does not make issue gone.

That said, assign dummy value and make the scope_guard() clear of its scope.
For the sake of consistency do it in the entire file.

Fixes: 7cc06e729460 ("platform/x86: ideapad-laptop: add a mutex to synchronize VPC commands")
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202408290219.BrPO8twi-lkp@intel.com/
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---

This has been Cc'ed to objtool and clang maintainers to have a look and
tell if this can be addressed in a better way.

 drivers/platform/x86/ideapad-laptop.c | 48 +++++++++++++++------------
 1 file changed, 27 insertions(+), 21 deletions(-)

diff --git a/drivers/platform/x86/ideapad-laptop.c b/drivers/platform/x86/ideapad-laptop.c
index 35c75bcff195..c64dfc56651d 100644
--- a/drivers/platform/x86/ideapad-laptop.c
+++ b/drivers/platform/x86/ideapad-laptop.c
@@ -554,13 +554,14 @@ static ssize_t camera_power_show(struct device *dev,
 				 char *buf)
 {
 	struct ideapad_private *priv = dev_get_drvdata(dev);
-	unsigned long result;
+	unsigned long result = 0;
 	int err;
 
-	scoped_guard(mutex, &priv->vpc_mutex)
+	scoped_guard(mutex, &priv->vpc_mutex) {
 		err = read_ec_data(priv->adev->handle, VPCCMD_R_CAMERA, &result);
-	if (err)
-		return err;
+		if (err)
+			return err;
+	}
 
 	return sysfs_emit(buf, "%d\n", !!result);
 }
@@ -577,10 +578,11 @@ static ssize_t camera_power_store(struct device *dev,
 	if (err)
 		return err;
 
-	scoped_guard(mutex, &priv->vpc_mutex)
+	scoped_guard(mutex, &priv->vpc_mutex) {
 		err = write_ec_cmd(priv->adev->handle, VPCCMD_W_CAMERA, state);
-	if (err)
-		return err;
+		if (err)
+			return err;
+	}
 
 	return count;
 }
@@ -628,13 +630,14 @@ static ssize_t fan_mode_show(struct device *dev,
 			     char *buf)
 {
 	struct ideapad_private *priv = dev_get_drvdata(dev);
-	unsigned long result;
+	unsigned long result = 0;
 	int err;
 
-	scoped_guard(mutex, &priv->vpc_mutex)
+	scoped_guard(mutex, &priv->vpc_mutex) {
 		err = read_ec_data(priv->adev->handle, VPCCMD_R_FAN, &result);
-	if (err)
-		return err;
+		if (err)
+			return err;
+	}
 
 	return sysfs_emit(buf, "%lu\n", result);
 }
@@ -654,10 +657,11 @@ static ssize_t fan_mode_store(struct device *dev,
 	if (state > 4 || state == 3)
 		return -EINVAL;
 
-	scoped_guard(mutex, &priv->vpc_mutex)
+	scoped_guard(mutex, &priv->vpc_mutex) {
 		err = write_ec_cmd(priv->adev->handle, VPCCMD_W_FAN, state);
-	if (err)
-		return err;
+		if (err)
+			return err;
+	}
 
 	return count;
 }
@@ -737,13 +741,14 @@ static ssize_t touchpad_show(struct device *dev,
 			     char *buf)
 {
 	struct ideapad_private *priv = dev_get_drvdata(dev);
-	unsigned long result;
+	unsigned long result = 0;
 	int err;
 
-	scoped_guard(mutex, &priv->vpc_mutex)
+	scoped_guard(mutex, &priv->vpc_mutex) {
 		err = read_ec_data(priv->adev->handle, VPCCMD_R_TOUCHPAD, &result);
-	if (err)
-		return err;
+		if (err)
+			return err;
+	}
 
 	priv->r_touchpad_val = result;
 
@@ -762,10 +767,11 @@ static ssize_t touchpad_store(struct device *dev,
 	if (err)
 		return err;
 
-	scoped_guard(mutex, &priv->vpc_mutex)
+	scoped_guard(mutex, &priv->vpc_mutex) {
 		err = write_ec_cmd(priv->adev->handle, VPCCMD_W_TOUCHPAD, state);
-	if (err)
-		return err;
+		if (err)
+			return err;
+	}
 
 	priv->r_touchpad_val = state;
 
-- 
2.43.0.rc1.1336.g36b5255a03ac