Re: [PATCH 2/5] Blackfin arch: SMP supporting patchset: Blackfin header files and machine common code

Bryan Wu
2008-11-19T08:20:39Z

On Wed, Nov 19, 2008 at 3:52 PM, gyang <graf.yang@analog.com> wrote:
>
> 在 2008-11-18二的 22:56 -0800，Andrew Morton写道：
>> On Tue, 18 Nov 2008 17:05:05 +0800 Bryan Wu <cooloney@kernel.org> wrote:
>>
>> > From: Graf Yang <graf.yang@analog.com>
>> >
>> > Blackfin dual core BF561 processor can support SMP like features.
>> > https://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:smp-like
>> >
>> > In this patch, we provide SMP extend to Blackfin header files
>> > and machine common code
>> >
>> >
>> > ...
>> >
>> > +#define atomic_add_unless(v, a, u) \
>> > +({ \
>> > + int c, old; \
>> > + c = atomic_read(v); \
>> > + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
>> > + c = old; \
>> > + c != (u); \
>> > +})
>>
>> The macro references its args multiple times and will do weird or
>> inefficient things when called with expressions which have
>> side-effects, or which do slow things.
>>
>> >
>> > ...
>> >
>> > +#include <asm/system.h> /* save_flags */
>> > +
>> > +static inline void set_bit(int nr, volatile unsigned long *addr)
>> > {
>> > int *a = (int *)addr;
>> > int mask;
>> > @@ -57,21 +91,23 @@ static __inline__ void clear_bit(int nr, volatile unsigned long *addr)
>> > a += nr >> 5;
>> > mask = 1 << (nr & 0x1f);
>> > local_irq_save(flags);
>> > - *a &= ~mask;
>> > + *a |= mask;
>>
>> I think you just broke clear_bit(). Maybe I'm misreading the diff.
> OK, We have corrected it on our own tree.

Both the code and the patch are all right. Because the mess from diff,
we all misread it.

-Bryan

>>
>> > local_irq_restore(flags);
>> > }
>> >
>> >
>> > ...
>> >
>> > +#define smp_mb__before_clear_bit() barrier()
>> > +#define smp_mb__after_clear_bit() barrier()
>> > +
>> > +static inline void __set_bit(int nr, volatile unsigned long *addr)
>> > +{
>> > + int *a = (int *)addr;
>> > + int mask;
>> > +
>> > + a += nr >> 5;
>> > + mask = 1 << (nr & 0x1f);
>> > + *a |= mask;
>> > +}
>> > +
>> > +static inline void __clear_bit(int nr, volatile unsigned long *addr)
>> > +{
>> > + int *a = (int *)addr;
>> > + int mask;
>> > +
>> > + a += nr >> 5;
>> > + mask = 1 << (nr & 0x1f);
>> > + *a &= ~mask;
>> > +}
>> > +
>> > +static inline void __change_bit(int nr, volatile unsigned long *addr)
>> > +{
>> > + int mask;
>> > + unsigned long *ADDR = (unsigned long *)addr;
>> > +
>> > + ADDR += nr >> 5;
>> > + mask = 1 << (nr & 31);
>> > + *ADDR ^= mask;
>> > +}
>>
>> I'm surprised there isn't any generic code which can be used for the above.
>>
>> >
>> > ...
>> >
>>
>> Gad what a lot of code. I don't think I have time to read it all, sorry.
>