On Fri, Sep 22, 2006 at 03:29:53PM +0900, Hirokazu Takata wrote:
>
> -#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
> +static inline int __raw_read_trylock(raw_rwlock_t *lock)
> +{
> + atomic_t *count = (atomic_t*)lock;
> + atomic_dec(count);
> + if (atomic_read(count) >= 0)
> + return 1;
> + atomic_inc(count);
> + return 0;
> +}
>
Is there a race here between __raw_read_trylock and __raw_write_trylock?
CPU A CPU B
__raw_read_trylock
atomic_dec(count);
__raw_write_trylock
atomic_sub_and_test(RW_LOCK_BIAS, count)
atomic_read(count)
It'd be fairly harmless as neither would manage to get the lock. But
I think it's not too hard to fix. Seems to me you want to do:
static inline int __raw_read_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t*)lock;
if (atomic_dec_return(count) >= 0)
return 1;
atomic_inc(count);
return 0;
}
eliminating the race.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
