On 05/05/2015 07:33 PM, Tahsin Erdogan wrote:
The conversion to signed happens with types shorter than int (__ticket_t
is either u8 or u16).
By changing Raghavendra's program to use unsigned short int, you can see
the problem:
================
#include <stdio.h>
#define LOCK_INC 2
int main()
{
unsigned short int head = 32700, tail=2;
if ((tail - head) > LOCK_INC)
printf(" tail - head > LOCK_INC \n");
else
printf(" tail - head < LOCK_INC \n");
return 0;
}
================
gcc -g -o t main.c
./t
tail - head < LOCK_INC
However, having just unsigned int returns the opposite result (unsigned
int head = 32700, tail=2;)
Interestingly,
#include <stdio.h>
//#define LOCK_INC ((unsigned int)2) // case 1
#define LOCK_INC 2 //case 2
int main()
{
unsigned short int head = 32700, tail=2;
if ((tail - head) > LOCK_INC)
printf(" tail - head > LOCK_INC \n");
else
printf(" tail - head < LOCK_INC \n");
return 0;
}
case 1 works here (PeterZ's stricter version)
case 2 gives tail - head < LOCK_INC
But is it not that we have case 1 we are looking here ?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
