linux-kernel - [PATCH AUTOSEL 4.4 9/9] ALSA: opti9xx: shut up gcc-10 range warning

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Date:   Thu,  7 May 2020 10:30:18 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>, Takashi Iwai <tiwai@...e.de>,
        Sasha Levin <sashal@...nel.org>, alsa-devel@...a-project.org
Subject: [PATCH AUTOSEL 4.4 9/9] ALSA: opti9xx: shut up gcc-10 range warning

From: Arnd Bergmann <arnd@...db.de>

[ Upstream commit 5ce00760a84848d008554c693ceb6286f4d9c509 ]

gcc-10 points out a few instances of suspicious integer arithmetic
leading to value truncation:

sound/isa/opti9xx/opti92x-ad1848.c: In function 'snd_opti9xx_configure':
sound/isa/opti9xx/opti92x-ad1848.c:322:43: error: overflow in conversion from 'int' to 'unsigned char' changes value from '(int)snd_opti9xx_read(chip, 3) & -256 | 240' to '240' [-Werror=overflow]
  322 |   (snd_opti9xx_read(chip, reg) & ~(mask)) | ((value) & (mask)))
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
sound/isa/opti9xx/opti92x-ad1848.c:351:3: note: in expansion of macro 'snd_opti9xx_write_mask'
  351 |   snd_opti9xx_write_mask(chip, OPTi9XX_MC_REG(3), 0xf0, 0xff);
      |   ^~~~~~~~~~~~~~~~~~~~~~
sound/isa/opti9xx/miro.c: In function 'snd_miro_configure':
sound/isa/opti9xx/miro.c:873:40: error: overflow in conversion from 'int' to 'unsigned char' changes value from '(int)snd_miro_read(chip, 3) & -256 | 240' to '240' [-Werror=overflow]
  873 |   (snd_miro_read(chip, reg) & ~(mask)) | ((value) & (mask)))
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
sound/isa/opti9xx/miro.c:1010:3: note: in expansion of macro 'snd_miro_write_mask'
 1010 |   snd_miro_write_mask(chip, OPTi9XX_MC_REG(3), 0xf0, 0xff);
      |   ^~~~~~~~~~~~~~~~~~~

These are all harmless here as only the low 8 bit are passed down
anyway. Change the macros to inline functions to make the code
more readable and also avoid the warning.

Strictly speaking those functions also need locking to make the
read/write pair atomic, but it seems unlikely that anyone would
still run into that issue.

Fixes: 1841f613fd2e ("[ALSA] Add snd-miro driver")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Link: https://lore.kernel.org/r/20200429190216.85919-1-arnd@arndb.de
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/isa/opti9xx/miro.c           | 9 ++++++---
 sound/isa/opti9xx/opti92x-ad1848.c | 9 ++++++---
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/sound/isa/opti9xx/miro.c b/sound/isa/opti9xx/miro.c
index 3a9067db1a842..7fbac24607bcf 100644
--- a/sound/isa/opti9xx/miro.c
+++ b/sound/isa/opti9xx/miro.c
@@ -875,10 +875,13 @@ static void snd_miro_write(struct snd_miro *chip, unsigned char reg,
 	spin_unlock_irqrestore(&chip->lock, flags);
 }
 
+static inline void snd_miro_write_mask(struct snd_miro *chip,
+		unsigned char reg, unsigned char value, unsigned char mask)
+{
+	unsigned char oldval = snd_miro_read(chip, reg);
 
-#define snd_miro_write_mask(chip, reg, value, mask)	\
-	snd_miro_write(chip, reg,			\
-		(snd_miro_read(chip, reg) & ~(mask)) | ((value) & (mask)))
+	snd_miro_write(chip, reg, (oldval & ~mask) | (value & mask));
+}
 
 /*
  *  Proc Interface
diff --git a/sound/isa/opti9xx/opti92x-ad1848.c b/sound/isa/opti9xx/opti92x-ad1848.c
index 0a52660037866..6777ae84b59e8 100644
--- a/sound/isa/opti9xx/opti92x-ad1848.c
+++ b/sound/isa/opti9xx/opti92x-ad1848.c
@@ -327,10 +327,13 @@ static void snd_opti9xx_write(struct snd_opti9xx *chip, unsigned char reg,
 }
 
 
-#define snd_opti9xx_write_mask(chip, reg, value, mask)	\
-	snd_opti9xx_write(chip, reg,			\
-		(snd_opti9xx_read(chip, reg) & ~(mask)) | ((value) & (mask)))
+static inline void snd_opti9xx_write_mask(struct snd_opti9xx *chip,
+		unsigned char reg, unsigned char value, unsigned char mask)
+{
+	unsigned char oldval = snd_opti9xx_read(chip, reg);
 
+	snd_opti9xx_write(chip, reg, (oldval & ~mask) | (value & mask));
+}
 
 static int snd_opti9xx_configure(struct snd_opti9xx *chip,
 					   long port,
-- 
2.20.1