openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

media: platform: vivid-cec: use 64-bit arithmetic instead of 32-bit 

Add suffix ULL to constant 10 in order to give the compiler complete
information about the proper arithmetic to use. Notice that this
constant is used in a context that expects an expression of type
u64 (64 bits, unsigned).

The expression len * 10 * CEC_TIM_DATA_BIT_TOTAL is currently being
evaluated using 32-bit arithmetic.

Also, remove unnecessary parentheses and add a code comment to make it
clear what is the reason of the code change.

Addresses-Coverity-ID: 1454996 ("Unintentional integer overflow")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Gustavo A. R. Silva 2018-02-06 11:53:44 -05:00 committed by Mauro Carvalho Chehab
parent eb64311ffc
commit fc49d3d7dc
1 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/media/platform/vivid/vivid-cec.c
View File

@ -70,8 +70,15 @@ static void vivid_cec_pin_adap_events(struct cec_adapter *adap, ktime_t ts,
if (adap == NULL)
return;
ts = ktime_sub_us(ts, (CEC_TIM_START_BIT_TOTAL +
len * 10 * CEC_TIM_DATA_BIT_TOTAL));
/*
* Suffix ULL on constant 10 makes the expression
* CEC_TIM_START_BIT_TOTAL + 10ULL * len * CEC_TIM_DATA_BIT_TOTAL
* to be evaluated using 64-bit unsigned arithmetic (u64), which
* is what ktime_sub_us expects as second argument.
*/
ts = ktime_sub_us(ts, CEC_TIM_START_BIT_TOTAL +
10ULL * len * CEC_TIM_DATA_BIT_TOTAL);
cec_queue_pin_cec_event(adap, false, ts);
ts = ktime_add_us(ts, CEC_TIM_START_BIT_LOW);
cec_queue_pin_cec_event(adap, true, ts);