Patch "Input: tca8418_keypad - hide gcc-4.9 -Wmaybe-uninitialized warning" has been added to the 4.9-stable tree

Patch "Input: tca8418_keypad - hide gcc-4.9 -Wmaybe-uninitialized warning" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Input: tca8418_keypad - hide gcc-4.9 -Wmaybe-uninitialized warning

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     input-tca8418_keypad-hide-gcc-4.9-wmaybe-uninitialized-warning.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ea4348c8462a20e8b1b6455a7145d2b86f8a49b6 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Wed, 26 Oct 2016 15:55:02 -0700
Subject: Input: tca8418_keypad - hide gcc-4.9 -Wmaybe-uninitialized warning
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Arnd Bergmann <arnd@arndb.de>

commit ea4348c8462a20e8b1b6455a7145d2b86f8a49b6 upstream.

Older versions of gcc warn about the tca8418_irq_handler function
as they can't keep track of the variable assignment inside of the
loop when using the -Wmaybe-unintialized flag:

drivers/input/keyboard/tca8418_keypad.c: In function ‘tca8418_irq_handler’:
drivers/input/keyboard/tca8418_keypad.c:172:9: error: ‘reg’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/input/keyboard/tca8418_keypad.c:165:5: note: ‘reg’ was declared here

This is fixed in gcc-6, but it's possible to rearrange the code
in a way that avoids the warning on older compilers as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/input/keyboard/tca8418_keypad.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

--- a/drivers/input/keyboard/tca8418_keypad.c
+++ b/drivers/input/keyboard/tca8418_keypad.c
@@ -164,11 +164,18 @@ static void tca8418_read_keypad(struct t
 	int error, col, row;
 	u8 reg, state, code;
 
-	/* Initial read of the key event FIFO */
-	error = tca8418_read_byte(keypad_data, REG_KEY_EVENT_A, &reg);
+	do {
+		error = tca8418_read_byte(keypad_data, REG_KEY_EVENT_A, &reg);
+		if (error < 0) {
+			dev_err(&keypad_data->client->dev,
+				"unable to read REG_KEY_EVENT_A\n");
+			break;
+		}
+
+		/* Assume that key code 0 signifies empty FIFO */
+		if (reg <= 0)
+			break;
 
-	/* Assume that key code 0 signifies empty FIFO */
-	while (error >= 0 && reg > 0) {
 		state = reg & KEY_EVENT_VALUE;
 		code  = reg & KEY_EVENT_CODE;
 
@@ -184,11 +191,7 @@ static void tca8418_read_keypad(struct t
 
 		/* Read for next loop */
 		error = tca8418_read_byte(keypad_data, REG_KEY_EVENT_A, &reg);
-	}
-
-	if (error < 0)
-		dev_err(&keypad_data->client->dev,
-			"unable to read REG_KEY_EVENT_A\n");
+	} while (1);
 
 	input_sync(input);
 }


Patches currently in stable-queue which might be from arnd@arndb.de are

queue-4.9/kasan-rework-kconfig-settings.patch
queue-4.9/tw5864-use-dev_warn-instead-of-warn-to-shut-up-warning.patch
queue-4.9/perf-x86-shut-up-false-positive-wmaybe-uninitialized-warning.patch
queue-4.9/go7007-add-media_camera_support-dependency.patch
queue-4.9/scsi-advansys-fix-build-warning-for-pci-n.patch
queue-4.9/video-fbdev-via-remove-possibly-unused-variables.patch
queue-4.9/drm-exynos-mark-pm-functions-as-__maybe_unused.patch
queue-4.9/binfmt_elf-compat-avoid-unused-function-warning.patch
queue-4.9/idle-i7300-add-pci-dependency.patch
queue-4.9/cw1200-fix-bogus-maybe-uninitialized-warning.patch
queue-4.9/x86-build-silence-the-build-with-make-s.patch
queue-4.9/gpio-xgene-mark-pm-functions-as-__maybe_unused.patch
queue-4.9/kvm-add-x86_local_apic-dependency.patch
queue-4.9/reiserfs-avoid-a-wmaybe-uninitialized-warning.patch
queue-4.9/scsi-advansys-fix-uninitialized-data-access.patch
queue-4.9/drm-i915-fix-intel_backlight_device_register-declaration.patch
queue-4.9/spi-bcm-qspi-shut-up-warning-about-cfi-header-inclusion.patch
queue-4.9/asoc-ux500-add-module_license-tag.patch
queue-4.9/x86-microcode-amd-change-load_microcode_amd-s-param-to-bool-to-fix-preemptibility-bug.patch
queue-4.9/video-fbdev-mmp-add-module_license.patch
queue-4.9/usb-phy-msm-add-regulator-dependency.patch
queue-4.9/arm64-dts-add-cooling-cells-to-cpu-nodes.patch
queue-4.9/vmxnet3-prevent-building-with-64k-pages.patch
queue-4.9/x86-platform-add-pci-dependency-for-punit_atom_debug.patch
queue-4.9/alsa-hda-ca0132-fix-possible-null-pointer-use.patch
queue-4.9/thermal-fix-intel_soc_dts_iosf_core-dependencies.patch
queue-4.9/arm64-define-bug-instruction-without-config_bug.patch
queue-4.9/arm64-sunxi-always-enable-reset-controller.patch
queue-4.9/tc358743-fix-register-i2c_rd-wr-functions.patch
queue-4.9/security-keys-big_key-requires-config_crypto.patch
queue-4.9/drm-i915-hide-unused-intel_panel_set_backlight-function.patch
queue-4.9/x86-fpu-math-emu-fix-possible-uninitialized-variable-use.patch
queue-4.9/arm-8743-1-bl_switcher-add-module_license-tag.patch
queue-4.9/em28xx-only-use-mt9v011-if-camera-support-is-enabled.patch
queue-4.9/arm64-fix-warning-about-swapper_pg_dir-overflow.patch
queue-4.9/shmem-avoid-maybe-uninitialized-warning.patch
queue-4.9/input-tca8418_keypad-hide-gcc-4.9-wmaybe-uninitialized-warning.patch
queue-4.9/drm-nouveau-hide-gcc-4.9-wmaybe-uninitialized.patch
queue-4.9/x86-add-multiuser-dependency-for-kvm.patch
queue-4.9/isdn-eicon-reduce-stack-size-of-sig_ind-function.patch