On Fri, May 09, 2014 at 10:51:55PM +0200, Peter Zijlstra wrote: > On Fri, May 09, 2014 at 10:43:09PM +0200, Peter Zijlstra wrote: > > On Fri, May 09, 2014 at 08:32:41PM +0200, Hans-Christian Egtvedt wrote: > > > > > - if (__builtin_constant_p(i) && (i >= -1048575) && (i <= > > > > 1048576)) > > > > - result = atomic_sub_return(-i, v); > > > > > > I do not recall why we did it like this any more, I would assume both sub > > > and > > > add to be single cycle instructions. > > Similarly, can I rip out atomic_sub_unless() ?
Something like so? --- Subject: arch,avr32: Fold atomic_ops From: Peter Zijlstra <[email protected]> Date: Wed Apr 9 21:51:29 CEST 2014 Many of the atomic op implementations are the same except for one instruction; fold the lot into a few CPP macros and reduce LoC. This also prepares for easy addition of new ops. Requires the asm_op because of eor. The avr32 sub instruction is limited to 21 bits, Hans-Christian cannot recall the reason for the weird __builtin_constant_p() tests so take all that out and use a straight fwd negate add instead of subtract. Cc: Hans-Christian Egtvedt <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Haavard Skinnemoen <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> --- arch/avr32/include/asm/atomic.h | 145 +++++++++++++++------------------------- 1 file changed, 55 insertions(+), 90 deletions(-) --- a/arch/avr32/include/asm/atomic.h +++ b/arch/avr32/include/asm/atomic.h @@ -22,117 +22,84 @@ #define atomic_read(v) (*(volatile int *)&(v)->counter) #define atomic_set(v, i) (((v)->counter) = i) -/* - * atomic_sub_return - subtract the atomic variable - * @i: integer value to subtract - * @v: pointer of type atomic_t - * - * Atomically subtracts @i from @v. Returns the resulting value. - */ -static inline int atomic_sub_return(int i, atomic_t *v) -{ - int result; - - asm volatile( - "/* atomic_sub_return */\n" - "1: ssrf 5\n" - " ld.w %0, %2\n" - " sub %0, %3\n" - " stcond %1, %0\n" - " brne 1b" - : "=&r"(result), "=o"(v->counter) - : "m"(v->counter), "rKs21"(i) - : "cc"); - - return result; +#define ATOMIC_OP(op, asm_op) \ +static inline void atomic_##op(int i, atomic_t *v) \ +{ \ + int result; \ + \ + asm volatile( \ + "/* atomic_" #op " */\n" \ + "1: ssrf 5\n" \ + " ld.w %0, %2\n" \ + " " #asm_op " %0, %3\n" \ + " stcond %1, %0\n" \ + " brne 1b" \ + : "=&r"(result), "=o"(v->counter) \ + : "m"(v->counter), "r"(i) \ + : "cc"); \ +} \ + +#define ATOMIC_OP_RETURN(op, asm_op) \ +static inline int atomic_##op##_return(int i, atomic_t *v) \ +{ \ + int result; \ + \ + asm volatile( \ + "/* atomic_" #op "_return */\n" \ + "1: ssrf 5\n" \ + " ld.w %0, %2\n" \ + " " #asm_op " %0, %3\n" \ + " stcond %1, %0\n" \ + " brne 1b" \ + : "=&r"(result), "=o"(v->counter) \ + : "m"(v->counter), "r"(i) \ + : "cc"); \ + \ + return result; \ } +#define ATOMIC_OPS(op, asm_op) \ + ATOMIC_OP(op, asm_op) \ + ATOMIC_OP_RETURN(op, asm_op) + +ATOMIC_OPS(add, add) + +#undef ATOMIC_OPS +#undef ATOMIC_OP_RETURN +#undef ATOMIC_OP + /* - * atomic_add_return - add integer to atomic variable - * @i: integer value to add - * @v: pointer of type atomic_t - * - * Atomically adds @i to @v. Returns the resulting value. + * The 'sub' instruction is limited to 21 bits, use negate add instead. */ -static inline int atomic_add_return(int i, atomic_t *v) -{ - int result; - - if (__builtin_constant_p(i) && (i >= -1048575) && (i <= 1048576)) - result = atomic_sub_return(-i, v); - else - asm volatile( - "/* atomic_add_return */\n" - "1: ssrf 5\n" - " ld.w %0, %1\n" - " add %0, %3\n" - " stcond %2, %0\n" - " brne 1b" - : "=&r"(result), "=o"(v->counter) - : "m"(v->counter), "r"(i) - : "cc", "memory"); - - return result; -} +#define atomic_sub(i, v) atomic_add(-(i), (v)) +#define atomic_sub_return(i, v) atomic_add_return(-(i), (v)) /* - * atomic_sub_unless - sub unless the number is a given value + * __atomic_add_unless - add unless the number is a given value * @v: pointer of type atomic_t - * @a: the amount to subtract from v... + * @a: the amount to add to v... * @u: ...unless v is equal to u. * - * Atomically subtract @a from @v, so long as it was not @u. + * Atomically adds @a to @v, so long as it was not @u. * Returns the old value of @v. */ -static inline void atomic_sub_unless(atomic_t *v, int a, int u) +static inline int __atomic_add_unless(atomic_t *v, int a, int u) { - int tmp; + int tmp, old = atomic_read(v); asm volatile( - "/* atomic_sub_unless */\n" + "/* __atomic_add_unless */\n" "1: ssrf 5\n" " ld.w %0, %2\n" " cp.w %0, %4\n" " breq 1f\n" - " sub %0, %3\n" + " add %0, %3\n" " stcond %1, %0\n" " brne 1b\n" "1:" : "=&r"(tmp), "=o"(v->counter) - : "m"(v->counter), "rKs21"(a), "rKs21"(u) + : "m"(v->counter), "r"(a), "ir"(u) : "cc", "memory"); -} - -/* - * __atomic_add_unless - add unless the number is a given value - * @v: pointer of type atomic_t - * @a: the amount to add to v... - * @u: ...unless v is equal to u. - * - * Atomically adds @a to @v, so long as it was not @u. - * Returns the old value of @v. -*/ -static inline int __atomic_add_unless(atomic_t *v, int a, int u) -{ - int tmp, old = atomic_read(v); - - if (__builtin_constant_p(a) && (a >= -1048575) && (a <= 1048576)) - atomic_sub_unless(v, -a, u); - else { - asm volatile( - "/* __atomic_add_unless */\n" - "1: ssrf 5\n" - " ld.w %0, %2\n" - " cp.w %0, %4\n" - " breq 1f\n" - " add %0, %3\n" - " stcond %1, %0\n" - " brne 1b\n" - "1:" - : "=&r"(tmp), "=o"(v->counter) - : "m"(v->counter), "r"(a), "ir"(u) - : "cc", "memory"); - } return old; } @@ -168,8 +135,6 @@ static inline int atomic_sub_if_positive #define atomic_xchg(v, new) (xchg(&((v)->counter), new)) #define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n))) -#define atomic_sub(i, v) (void)atomic_sub_return(i, v) -#define atomic_add(i, v) (void)atomic_add_return(i, v) #define atomic_dec(v) atomic_sub(1, (v)) #define atomic_inc(v) atomic_add(1, (v)) -- 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/
