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authorPeter Zijlstra <peterz@infradead.org>2016-04-18 02:16:09 +0300
committerIngo Molnar <mingo@kernel.org>2016-06-16 11:48:20 +0300
commitfbffe892e5253dd02c016c59a9d792eafe9d53e1 (patch)
tree668ef1af920c73d04fac72baf07a817d65d14a5a /arch/arc
parent1f51dee7ca7424be6f84067395166f878dbdd8be (diff)
downloadlinux-fbffe892e5253dd02c016c59a9d792eafe9d53e1.tar.xz
locking/atomic, arch/arc: Implement atomic_fetch_{add,sub,and,andnot,or,xor}()
Implement FETCH-OP atomic primitives, these are very similar to the existing OP-RETURN primitives we already have, except they return the value of the atomic variable _before_ modification. This is especially useful for irreversible operations -- such as bitops (because it becomes impossible to reconstruct the state prior to modification). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Vineet Gupta <vgupta@synopsys.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Noam Camus <noamc@ezchip.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-snps-arc@lists.infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/include/asm/atomic.h103
1 files changed, 94 insertions, 9 deletions
diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
index dd683995bc9d..c066a21caaaf 100644
--- a/arch/arc/include/asm/atomic.h
+++ b/arch/arc/include/asm/atomic.h
@@ -67,6 +67,37 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return val; \
}
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned int val, orig; \
+ SCOND_FAIL_RETRY_VAR_DEF \
+ \
+ /* \
+ * Explicit full memory barrier needed before/after as \
+ * LLOCK/SCOND thmeselves don't provide any such semantics \
+ */ \
+ smp_mb(); \
+ \
+ __asm__ __volatile__( \
+ "1: llock %[orig], [%[ctr]] \n" \
+ " " #asm_op " %[val], %[orig], %[i] \n" \
+ " scond %[val], [%[ctr]] \n" \
+ " \n" \
+ SCOND_FAIL_RETRY_ASM \
+ \
+ : [val] "=&r" (val), \
+ [orig] "=&r" (orig) \
+ SCOND_FAIL_RETRY_VARS \
+ : [ctr] "r" (&v->counter), \
+ [i] "ir" (i) \
+ : "cc"); \
+ \
+ smp_mb(); \
+ \
+ return orig; \
+}
+
#else /* !CONFIG_ARC_HAS_LLSC */
#ifndef CONFIG_SMP
@@ -129,21 +160,46 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return temp; \
}
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned long flags; \
+ unsigned long orig; \
+ \
+ /* \
+ * spin lock/unlock provides the needed smp_mb() before/after \
+ */ \
+ atomic_ops_lock(flags); \
+ orig = v->counter; \
+ v->counter c_op i; \
+ atomic_ops_unlock(flags); \
+ \
+ return orig; \
+}
+
#endif /* !CONFIG_ARC_HAS_LLSC */
#define ATOMIC_OPS(op, c_op, asm_op) \
ATOMIC_OP(op, c_op, asm_op) \
- ATOMIC_OP_RETURN(op, c_op, asm_op)
+ ATOMIC_OP_RETURN(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
ATOMIC_OPS(add, +=, add)
ATOMIC_OPS(sub, -=, sub)
#define atomic_andnot atomic_andnot
-ATOMIC_OP(and, &=, and)
-ATOMIC_OP(andnot, &= ~, bic)
-ATOMIC_OP(or, |=, or)
-ATOMIC_OP(xor, ^=, xor)
+#define atomic_fetch_or atomic_fetch_or
+
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, c_op, asm_op) \
+ ATOMIC_OP(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
+
+ATOMIC_OPS(and, &=, and)
+ATOMIC_OPS(andnot, &= ~, bic)
+ATOMIC_OPS(or, |=, or)
+ATOMIC_OPS(xor, ^=, xor)
#undef SCOND_FAIL_RETRY_VAR_DEF
#undef SCOND_FAIL_RETRY_ASM
@@ -208,22 +264,51 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return temp; \
}
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned int temp = i; \
+ \
+ /* Explicit full memory barrier needed before/after */ \
+ smp_mb(); \
+ \
+ __asm__ __volatile__( \
+ " mov r2, %0\n" \
+ " mov r3, %1\n" \
+ " .word %2\n" \
+ " mov %0, r2" \
+ : "+r"(temp) \
+ : "r"(&v->counter), "i"(asm_op) \
+ : "r2", "r3", "memory"); \
+ \
+ smp_mb(); \
+ \
+ return temp; \
+}
+
#define ATOMIC_OPS(op, c_op, asm_op) \
ATOMIC_OP(op, c_op, asm_op) \
- ATOMIC_OP_RETURN(op, c_op, asm_op)
+ ATOMIC_OP_RETURN(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
ATOMIC_OPS(add, +=, CTOP_INST_AADD_DI_R2_R2_R3)
#define atomic_sub(i, v) atomic_add(-(i), (v))
#define atomic_sub_return(i, v) atomic_add_return(-(i), (v))
-ATOMIC_OP(and, &=, CTOP_INST_AAND_DI_R2_R2_R3)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, c_op, asm_op) \
+ ATOMIC_OP(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
+
+ATOMIC_OPS(and, &=, CTOP_INST_AAND_DI_R2_R2_R3)
#define atomic_andnot(mask, v) atomic_and(~(mask), (v))
-ATOMIC_OP(or, |=, CTOP_INST_AOR_DI_R2_R2_R3)
-ATOMIC_OP(xor, ^=, CTOP_INST_AXOR_DI_R2_R2_R3)
+ATOMIC_OPS(or, |=, CTOP_INST_AOR_DI_R2_R2_R3)
+ATOMIC_OPS(xor, ^=, CTOP_INST_AXOR_DI_R2_R2_R3)
#endif /* CONFIG_ARC_PLAT_EZNPS */
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP