On 08/30/2018 02:51 AM, Will Deacon wrote:
> Yeah, the bit_spin_lock()/__bit_spin_unlock() race described in f75d48644c56a
> boils down to concurrent atomic_long_set_release() vs
> atomic_long_fetch_or_acquire(), which really needs to work.
I don't see how: __clear_bit_unlock() reads @old, flips a bit and then calls
atomic_long_set_release() so the race is not just with set_release.
static inline int test_and_set_bit_lock(unsigned int nr, volatile unsigned
long *p)
{
long old;
unsigned long mask = (1UL << ((nr) % 32));
p += ((nr) / 32);
old = atomic_long_fetch_or_acquire(mask, (atomic_long_t *)p);
return !!(old & mask);
}
static inline void __clear_bit_unlock(unsigned int nr, volatile unsigned
long *p)
{
unsigned long old;
p += ((nr) / 32);
old = // soem typecheck magic on *p
old &= ~(1UL << ((nr) % 32));
atomic_long_set_release((atomic_long_t *)p, old);
}
_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc
