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[media] tuners: Don't use dynamic static allocation

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Dynamic static allocation is evil, as Kernel stack is too low, and
compilation complains about it on some archs:
	drivers/media/tuners/e4000.c:50:1: warning: 'e4000_wr_regs' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/e4000.c:83:1: warning: 'e4000_rd_regs' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/fc2580.c:66:1: warning: 'fc2580_wr_regs.constprop.1' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/fc2580.c:98:1: warning: 'fc2580_rd_regs.constprop.0' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/tda18212.c:57:1: warning: 'tda18212_wr_regs' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/tda18212.c:90:1: warning: 'tda18212_rd_regs.constprop.0' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/tda18218.c:60:1: warning: 'tda18218_wr_regs' uses dynamic stack allocation [enabled by default]
	drivers/media/tuners/tda18218.c:92:1: warning: 'tda18218_rd_regs.constprop.0' uses dynamic stack allocation [enabled by default]
Instead, let's enforce a limit for the buffer. Considering that I2C
transfers are generally limited, and that devices used on USB has a
max data length of 64 bytes for	the control URBs.
So, it seem safe to use 64 bytes as the hard limit for all those devices.
 On most cases, the limit is a way lower than that, but	this limit
is small enough to not affect the Kernel stack, and it is a no brain
limit, as using smaller ones would require to either carefully each
driver or to take a look on each datasheet.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Mauro Carvalho Chehab
2013-11-02 06:07:42 -03:00
parent 5bf30b3bc4
commit f1baab870f
4 changed files with 83 additions and 15 deletions
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25
drivers/media/tuners/e4000.c
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@@ -20,20 +20,30 @@
#include "e4000_priv.h"
/* Max transfer size done by I2C transfer functions */
#define MAX_XFER_SIZE 64
/* write multiple registers */
static int e4000_wr_regs(struct e4000_priv *priv, u8 reg, u8 *val, int len)
{
int ret;
u8 buf[1 + len];
u8 buf[MAX_XFER_SIZE];
struct i2c_msg msg[1] = {
{
.addr = priv->cfg->i2c_addr,
.flags = 0,
.len = sizeof(buf),
.len = 1 + len,
.buf = buf,
}
};
if (1 + len > sizeof(buf)) {
dev_warn(&priv->i2c->dev,
"%s: i2c wr reg=%04x: len=%d is too big!\n",
KBUILD_MODNAME, reg, len);
return -EINVAL;
}
buf[0] = reg;
memcpy(&buf[1], val, len);
@@ -53,7 +63,7 @@ static int e4000_wr_regs(struct e4000_priv *priv, u8 reg, u8 *val, int len)
static int e4000_rd_regs(struct e4000_priv *priv, u8 reg, u8 *val, int len)
{
int ret;
u8 buf[len];
u8 buf[MAX_XFER_SIZE];
struct i2c_msg msg[2] = {
{
.addr = priv->cfg->i2c_addr,
@@ -63,11 +73,18 @@ static int e4000_rd_regs(struct e4000_priv *priv, u8 reg, u8 *val, int len)
}, {
.addr = priv->cfg->i2c_addr,
.flags = I2C_M_RD,
.len = sizeof(buf),
.len = len,
.buf = buf,
}
};
if (len > sizeof(buf)) {
dev_warn(&priv->i2c->dev,
"%s: i2c rd reg=%04x: len=%d is too big!\n",
KBUILD_MODNAME, reg, len);
return -EINVAL;
}
ret = i2c_transfer(priv->i2c, msg, 2);
if (ret == 2) {
memcpy(val, buf, len);