3da86ee4f1
These functions depend on "result" being initalized to 0, but "result" is not included as an input constraint to the inline assembly block following its initialization, only as an output constraint. Thus gcc thinks it doesn't need to initialize it, so result ends up undefined if the "unless" condition is true. This fixes an oops in sunrpc where the faulty atomics caused rpciod_up() to not start the workqueue as it should. Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
202 lines
5 KiB
C
202 lines
5 KiB
C
/*
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* Atomic operations that C can't guarantee us. Useful for
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* resource counting etc.
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*
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* But use these as seldom as possible since they are slower than
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* regular operations.
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*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_ATOMIC_H
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#define __ASM_AVR32_ATOMIC_H
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#include <asm/system.h>
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typedef struct { volatile int counter; } atomic_t;
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#define ATOMIC_INIT(i) { (i) }
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#define atomic_read(v) ((v)->counter)
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#define atomic_set(v, i) (((v)->counter) = i)
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/*
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* atomic_sub_return - subtract the atomic variable
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* @i: integer value to subtract
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* @v: pointer of type atomic_t
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*
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* Atomically subtracts @i from @v. Returns the resulting value.
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*/
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static inline int atomic_sub_return(int i, atomic_t *v)
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{
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int result;
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asm volatile(
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"/* atomic_sub_return */\n"
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"1: ssrf 5\n"
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" ld.w %0, %2\n"
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" sub %0, %3\n"
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" stcond %1, %0\n"
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" brne 1b"
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: "=&r"(result), "=o"(v->counter)
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: "m"(v->counter), "rKs21"(i)
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: "cc");
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return result;
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}
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/*
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* atomic_add_return - add integer to atomic variable
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* @i: integer value to add
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* @v: pointer of type atomic_t
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*
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* Atomically adds @i to @v. Returns the resulting value.
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*/
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static inline int atomic_add_return(int i, atomic_t *v)
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{
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int result;
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if (__builtin_constant_p(i) && (i >= -1048575) && (i <= 1048576))
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result = atomic_sub_return(-i, v);
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else
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asm volatile(
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"/* atomic_add_return */\n"
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"1: ssrf 5\n"
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" ld.w %0, %1\n"
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" add %0, %3\n"
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" stcond %2, %0\n"
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" brne 1b"
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: "=&r"(result), "=o"(v->counter)
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: "m"(v->counter), "r"(i)
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: "cc", "memory");
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return result;
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}
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/*
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* atomic_sub_unless - sub unless the number is a given value
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* @v: pointer of type atomic_t
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* @a: the amount to add to v...
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* @u: ...unless v is equal to u.
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*
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* If the atomic value v is not equal to u, this function subtracts a
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* from v, and returns non zero. If v is equal to u then it returns
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* zero. This is done as an atomic operation.
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*/
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static inline int atomic_sub_unless(atomic_t *v, int a, int u)
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{
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int tmp, result = 0;
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asm volatile(
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"/* atomic_sub_unless */\n"
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"1: ssrf 5\n"
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" ld.w %0, %3\n"
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" cp.w %0, %5\n"
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" breq 1f\n"
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" sub %0, %4\n"
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" stcond %2, %0\n"
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" brne 1b\n"
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" mov %1, 1\n"
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"1:"
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: "=&r"(tmp), "=&r"(result), "=o"(v->counter)
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: "m"(v->counter), "rKs21"(a), "rKs21"(u), "1"(result)
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: "cc", "memory");
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return result;
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}
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/*
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* atomic_add_unless - add unless the number is a given value
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* @v: pointer of type atomic_t
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* @a: the amount to add to v...
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* @u: ...unless v is equal to u.
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*
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* If the atomic value v is not equal to u, this function adds a to v,
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* and returns non zero. If v is equal to u then it returns zero. This
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* is done as an atomic operation.
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*/
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static inline int atomic_add_unless(atomic_t *v, int a, int u)
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{
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int tmp, result;
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if (__builtin_constant_p(a) && (a >= -1048575) && (a <= 1048576))
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result = atomic_sub_unless(v, -a, u);
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else {
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result = 0;
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asm volatile(
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"/* atomic_add_unless */\n"
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"1: ssrf 5\n"
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" ld.w %0, %3\n"
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" cp.w %0, %5\n"
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" breq 1f\n"
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" add %0, %4\n"
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" stcond %2, %0\n"
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" brne 1b\n"
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" mov %1, 1\n"
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"1:"
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: "=&r"(tmp), "=&r"(result), "=o"(v->counter)
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: "m"(v->counter), "r"(a), "ir"(u), "1"(result)
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: "cc", "memory");
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}
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return result;
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}
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/*
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* atomic_sub_if_positive - conditionally subtract integer from atomic variable
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* @i: integer value to subtract
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* @v: pointer of type atomic_t
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*
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* Atomically test @v and subtract @i if @v is greater or equal than @i.
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* The function returns the old value of @v minus @i.
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*/
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static inline int atomic_sub_if_positive(int i, atomic_t *v)
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{
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int result;
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asm volatile(
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"/* atomic_sub_if_positive */\n"
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"1: ssrf 5\n"
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" ld.w %0, %2\n"
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" sub %0, %3\n"
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" brlt 1f\n"
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" stcond %1, %0\n"
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" brne 1b\n"
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"1:"
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: "=&r"(result), "=o"(v->counter)
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: "m"(v->counter), "ir"(i)
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: "cc", "memory");
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return result;
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}
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#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
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#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
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#define atomic_sub(i, v) (void)atomic_sub_return(i, v)
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#define atomic_add(i, v) (void)atomic_add_return(i, v)
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#define atomic_dec(v) atomic_sub(1, (v))
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#define atomic_inc(v) atomic_add(1, (v))
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#define atomic_dec_return(v) atomic_sub_return(1, v)
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#define atomic_inc_return(v) atomic_add_return(1, v)
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#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
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#define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
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#define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
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#define atomic_add_negative(i, v) (atomic_add_return(i, v) < 0)
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#define atomic_inc_not_zero(v) atomic_add_unless(v, 1, 0)
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#define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
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#define smp_mb__before_atomic_dec() barrier()
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#define smp_mb__after_atomic_dec() barrier()
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#define smp_mb__before_atomic_inc() barrier()
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#define smp_mb__after_atomic_inc() barrier()
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#include <asm-generic/atomic.h>
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#endif /* __ASM_AVR32_ATOMIC_H */
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