From: Richard Fitzgerald rf@opensource.cirrus.com
stable inclusion from linux-4.19.198 commit 7fb82d7854198d15ee3f87c255e10ec8c9fe0347
--------------------------------
[ Upstream commit d327ea15a305024ef0085252fa3657bbb1ce25f5 ]
sparse generates the following warning:
include/linux/prandom.h:114:45: sparse: sparse: cast truncates bits from constant value
This is because the 64-bit seed value is manipulated and then placed in a u32, causing an implicit cast and truncation. A forced cast to u32 doesn't prevent this warning, which is reasonable because a typecast doesn't prove that truncation was expected.
Logical-AND the value with 0xffffffff to make explicit that truncation to 32-bit is intended.
Reported-by: kernel test robot lkp@intel.com Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com Reviewed-by: Petr Mladek pmladek@suse.com Signed-off-by: Petr Mladek pmladek@suse.com Link: https://lore.kernel.org/r/20210525122012.6336-3-rf@opensource.cirrus.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- include/linux/prandom.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/prandom.h b/include/linux/prandom.h index cc1e71334e53c..e20339c78a84c 100644 --- a/include/linux/prandom.h +++ b/include/linux/prandom.h @@ -93,7 +93,7 @@ static inline u32 __seed(u32 x, u32 m) */ static inline void prandom_seed_state(struct rnd_state *state, u64 seed) { - u32 i = (seed >> 32) ^ (seed << 10) ^ seed; + u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL;
state->s1 = __seed(i, 2U); state->s2 = __seed(i, 8U);