linux-kernel - [PATCH 1/3] media: saa7146: avoid high stack usage with clang

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Date:   Tue, 19 Feb 2019 18:01:56 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Mark Brown <broonie@...nel.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] media: saa7146: avoid high stack usage with clang

Two saa7146/hexium files contain a construct that causes a warning
when built with clang:

drivers/media/pci/saa7146/hexium_orion.c:210:12: error: stack frame size of 2272 bytes in function 'hexium_probe'
      [-Werror,-Wframe-larger-than=]
static int hexium_probe(struct saa7146_dev *dev)
           ^
drivers/media/pci/saa7146/hexium_gemini.c:257:12: error: stack frame size of 2304 bytes in function 'hexium_attach'
      [-Werror,-Wframe-larger-than=]
static int hexium_attach(struct saa7146_dev *dev, struct saa7146_pci_extension_data *info)
           ^

This one happens regardless of KASAN, and the problem is that a
constructor to initalize a dynamically allocated structure leads
to a copy of that structure on the stack, whereas gcc initializes
it in place.

Link: https://bugs.llvm.org/show_bug.cgi?id=40776
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/media/pci/saa7146/hexium_gemini.c | 4 +---
 drivers/media/pci/saa7146/hexium_orion.c  | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/media/pci/saa7146/hexium_gemini.c b/drivers/media/pci/saa7146/hexium_gemini.c
index 5817d9cde4d0..f7ce0e1770bf 100644
--- a/drivers/media/pci/saa7146/hexium_gemini.c
+++ b/drivers/media/pci/saa7146/hexium_gemini.c
@@ -270,9 +270,7 @@ static int hexium_attach(struct saa7146_dev *dev, struct saa7146_pci_extension_d
 	/* enable i2c-port pins */
 	saa7146_write(dev, MC1, (MASK_08 | MASK_24 | MASK_10 | MASK_26));
 
-	hexium->i2c_adapter = (struct i2c_adapter) {
-		.name = "hexium gemini",
-	};
+	strscpy(hexium->i2c_adapter.name, "hexium gemini", sizeof(hexium->i2c_adapter.name));
 	saa7146_i2c_adapter_prepare(dev, &hexium->i2c_adapter, SAA7146_I2C_BUS_BIT_RATE_480);
 	if (i2c_add_adapter(&hexium->i2c_adapter) < 0) {
 		DEB_S("cannot register i2c-device. skipping.\n");
diff --git a/drivers/media/pci/saa7146/hexium_orion.c b/drivers/media/pci/saa7146/hexium_orion.c
index 0a05176c18ab..b9f4a09c744d 100644
--- a/drivers/media/pci/saa7146/hexium_orion.c
+++ b/drivers/media/pci/saa7146/hexium_orion.c
@@ -231,9 +231,7 @@ static int hexium_probe(struct saa7146_dev *dev)
 	saa7146_write(dev, DD1_STREAM_B, 0x00000000);
 	saa7146_write(dev, MC2, (MASK_09 | MASK_25 | MASK_10 | MASK_26));
 
-	hexium->i2c_adapter = (struct i2c_adapter) {
-		.name = "hexium orion",
-	};
+	strscpy(hexium->i2c_adapter.name, "hexium orion", sizeof(hexium->i2c_adapter.name));
 	saa7146_i2c_adapter_prepare(dev, &hexium->i2c_adapter, SAA7146_I2C_BUS_BIT_RATE_480);
 	if (i2c_add_adapter(&hexium->i2c_adapter) < 0) {
 		DEB_S("cannot register i2c-device. skipping.\n");
-- 
2.20.0