Improve atomic.h robustness

I've maintained this patch, originally from Thiemo Seufer in 2004, for a
really long time, but I think it's time for it to get a look at for
possible inclusion. I have had no problems with it across various SGI
systems over the years.

To quote the post here:
http://www.linux-mips.org/archives/linux-mips/2004-12/msg00000.html

"the atomic functions use so far memory references for the inline
assembler to access the semaphore. This can lead to additional
instructions in the ll/sc loop, because newer compilers don't
expand the memory reference any more but leave it to the assembler.

The appended patch uses registers instead, and makes the ll/sc
arguments more explicit. In some cases it will lead also to better
register scheduling because the register isn't bound to an output
any more."

Signed-off-by: Joshua Kinard <[e-mail]>
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/4029/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/include/asm/atomic.h

···
 		"	sc	%0, %1					\n"
 		"	beqzl	%0, 1b					\n"
 		"	.set	mips0					\n"
-		: "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter));
+		: "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else if (kernel_uses_llsc) {
 		int temp;
 
···
 			"	addu	%0, %2				\n"
 			"	sc	%0, %1				\n"
 			"	.set	mips0				\n"
-			: "=&r" (temp), "=m" (v->counter)
-			: "Ir" (i), "m" (v->counter));
+			: "=&r" (temp), "+m" (v->counter)
+			: "Ir" (i));
 		} while (unlikely(!temp));
 	} else {
 		unsigned long flags;
···
 		"	sc	%0, %1					\n"
 		"	beqzl	%0, 1b					\n"
 		"	.set	mips0					\n"
-		: "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter));
+		: "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else if (kernel_uses_llsc) {
 		int temp;
 
···
 			"	subu	%0, %2				\n"
 			"	sc	%0, %1				\n"
 			"	.set	mips0				\n"
-			: "=&r" (temp), "=m" (v->counter)
-			: "Ir" (i), "m" (v->counter));
+			: "=&r" (temp), "+m" (v->counter)
+			: "Ir" (i));
 		} while (unlikely(!temp));
 	} else {
 		unsigned long flags;
···
 		"	beqzl	%0, 1b					\n"
 		"	addu	%0, %1, %3				\n"
 		"	.set	mips0					\n"
-		: "=&r" (result), "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter)
-		: "memory");
+		: "=&r" (result), "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else if (kernel_uses_llsc) {
 		int temp;
 
···
 			"	addu	%0, %1, %3			\n"
 			"	sc	%0, %2				\n"
 			"	.set	mips0				\n"
-			: "=&r" (result), "=&r" (temp), "=m" (v->counter)
-			: "Ir" (i), "m" (v->counter)
-			: "memory");
+			: "=&r" (result), "=&r" (temp), "+m" (v->counter)
+			: "Ir" (i));
 		} while (unlikely(!result));
 
 		result = temp + i;
···
 			"	subu	%0, %1, %3			\n"
 			"	sc	%0, %2				\n"
 			"	.set	mips0				\n"
-			: "=&r" (result), "=&r" (temp), "=m" (v->counter)
-			: "Ir" (i), "m" (v->counter)
-			: "memory");
+			: "=&r" (result), "=&r" (temp), "+m" (v->counter)
+			: "Ir" (i));
 		} while (unlikely(!result));
 
 		result = temp - i;
···
 		"	.set	reorder					\n"
 		"1:							\n"
 		"	.set	mips0					\n"
-		: "=&r" (result), "=&r" (temp), "=m" (v->counter)
+		: "=&r" (result), "=&r" (temp), "+m" (v->counter)
 		: "Ir" (i), "m" (v->counter)
 		: "memory");
 	} else if (kernel_uses_llsc) {
···
 		"	.set	reorder					\n"
 		"1:							\n"
 		"	.set	mips0					\n"
-		: "=&r" (result), "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter)
-		: "memory");
+		: "=&r" (result), "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else {
 		unsigned long flags;
 
···
 		"	scd	%0, %1					\n"
 		"	beqzl	%0, 1b					\n"
 		"	.set	mips0					\n"
-		: "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter));
+		: "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else if (kernel_uses_llsc) {
 		long temp;
 
···
 			"	daddu	%0, %2				\n"
 			"	scd	%0, %1				\n"
 			"	.set	mips0				\n"
-			: "=&r" (temp), "=m" (v->counter)
-			: "Ir" (i), "m" (v->counter));
+			: "=&r" (temp), "+m" (v->counter)
+			: "Ir" (i));
 		} while (unlikely(!temp));
 	} else {
 		unsigned long flags;
···
 		"	scd	%0, %1					\n"
 		"	beqzl	%0, 1b					\n"
 		"	.set	mips0					\n"
-		: "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter));
+		: "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else if (kernel_uses_llsc) {
 		long temp;
 
···
 			"	dsubu	%0, %2				\n"
 			"	scd	%0, %1				\n"
 			"	.set	mips0				\n"
-			: "=&r" (temp), "=m" (v->counter)
-			: "Ir" (i), "m" (v->counter));
+			: "=&r" (temp), "+m" (v->counter)
+			: "Ir" (i));
 		} while (unlikely(!temp));
 	} else {
 		unsigned long flags;
···
 		"	beqzl	%0, 1b					\n"
 		"	daddu	%0, %1, %3				\n"
 		"	.set	mips0					\n"
-		: "=&r" (result), "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter)
-		: "memory");
+		: "=&r" (result), "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else if (kernel_uses_llsc) {
 		long temp;
 
···
 		"	.set	reorder					\n"
 		"1:							\n"
 		"	.set	mips0					\n"
-		: "=&r" (result), "=&r" (temp), "=m" (v->counter)
-		: "Ir" (i), "m" (v->counter)
-		: "memory");
+		: "=&r" (result), "=&r" (temp), "+m" (v->counter)
+		: "Ir" (i));
 	} else {
 		unsigned long flags;