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media: r820t: fix r820t_write_reg for KASAN

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With CONFIG_KASAN, we get an overly long stack frame due to inlining
the register access functions:

drivers/media/tuners/r820t.c: In function 'generic_set_freq.isra.7':
drivers/media/tuners/r820t.c:1334:1: error: the frame size of 2880 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

This is caused by a gcc bug that has now been fixed in gcc-8.
To work around the problem, we can pass the register data
through a local variable that older gcc versions can optimize
out as well.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Arnd Bergmann 2017-11-30 06:08:05 -05:00 committed by Mauro Carvalho Chehab
parent 0ca4e31304
commit 16c3ada89c
1 changed files with 8 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

13
drivers/media/tuners/r820t.c
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@ -384,9 +384,11 @@ static int r820t_write(struct r820t_priv *priv, u8 reg, const u8 *val,
return 0; return 0;
} }
static int r820t_write_reg(struct r820t_priv *priv, u8 reg, u8 val) static inline int r820t_write_reg(struct r820t_priv *priv, u8 reg, u8 val)
{ {
return r820t_write(priv, reg, &val, 1); u8 tmp = val; /* work around GCC PR81715 with asan-stack=1 */
return r820t_write(priv, reg, &tmp, 1);
} }
static int r820t_read_cache_reg(struct r820t_priv *priv, int reg) static int r820t_read_cache_reg(struct r820t_priv *priv, int reg)
@ -399,17 +401,18 @@ static int r820t_read_cache_reg(struct r820t_priv *priv, int reg)
return -EINVAL; return -EINVAL;
} }
static int r820t_write_reg_mask(struct r820t_priv *priv, u8 reg, u8 val, static inline int r820t_write_reg_mask(struct r820t_priv *priv, u8 reg, u8 val,
u8 bit_mask) u8 bit_mask)
{ {
u8 tmp = val;
int rc = r820t_read_cache_reg(priv, reg); int rc = r820t_read_cache_reg(priv, reg);
if (rc < 0) if (rc < 0)
return rc; return rc;
val = (rc & ~bit_mask) | (val & bit_mask); tmp = (rc & ~bit_mask) | (tmp & bit_mask);
return r820t_write(priv, reg, &val, 1); return r820t_write(priv, reg, &tmp, 1);
} }
static int r820t_read(struct r820t_priv *priv, u8 reg, u8 *val, int len) static int r820t_read(struct r820t_priv *priv, u8 reg, u8 *val, int len)