x86/atom: use correct names in asm, improve docs

arch/x86/include/arch/atom.h

@@ -32,10 +32,10 @@ inline int atom_write(atom_t *atom, int val)
 	int eax;
 
 	__asm__ volatile(
-"	mov	(%2),	%0	\n"
+"	mov	(%2),	%0	\n" /* eax = atom->_value */
 "1:	lock			\n"
-"	cmpxchgl %1, (%2)	\n"
-"	jne	1b		\n"
+"	cmpxchgl %1, (%2)	\n" /* if (atom->_value == eax) atom->_value = val */
+"	jne	1b		\n" /* else goto 1 (eax updated to new atom->_value) */
 	: "=a"(eax)
 	: "r"(val), "r"(&atom->_value)
 	: "cc", "memory"
@@ -109,9 +109,9 @@ inline bool atom_dec(atom_t *atom)
 	bool nonzero = false;
 
 	__asm__ volatile(
-	"	lock		\n"
-	"	decl	(%1)	\n"
-	"	setne	%0	\n"
+"	lock		\n"
+"	decl	(%1)	\n"
+"	setne	%0	\n"
 	: "+r"(nonzero) /* read+write to ensure the initial value isn't optimized out */
 	: "r"(&atom->_value)
 	: "cc", "memory"
@@ -136,7 +136,7 @@ inline int atom_and(atom_t *atom, int val)
 "1:	andl	%0, %1		\n" /* val &= eax */
 "	lock			\n"
 "	cmpxchgl %1, (%2)	\n" /* if (atom->_value == eax) atom->_value = val */
-"	jne	1b		\n" /* else goto 1 */
+"	jne	1b		\n" /* else goto 1 (eax updated to new atom->_value) */
 	: "=a"(eax), "+r"(val)
 	: "r"(&atom->_value)
 	: "cc", "memory"
@@ -161,7 +161,7 @@ inline int atom_or(atom_t *atom, int val)
 "1:	orl	%0,	%1	\n" /* eax |= eax */
 "	lock			\n"
 "	cmpxchgl %1,	(%2)	\n" /* if (atom->_value == eax) atom->_value = eax */
-"	jne	1b		\n" /* else goto 1 */
+"	jne	1b		\n" /* else goto 1 (eax updated to new atom->_value) */
 	: "=a"(eax), "+r"(val)
 	: "r"(&atom->_value)
 	: "cc", "memory"
@@ -183,10 +183,10 @@ inline int atom_xor(atom_t *atom, int val)
 
 	__asm__ volatile(
 "	movl	(%2),	%0	\n" /* eax = atom->_value */
-"1:	xorl	%0,	%1	\n" /* eax ^= eax */
+"1:	xorl	%0,	%1	\n" /* val ^= eax */
 "	lock			\n"
 "	cmpxchgl %1,	(%2)	\n" /* if (atom->_value == eax) atom->_value = eax */
-"	jne	1b		\n" /* else goto 1 */
+"	jne	1b		\n" /* else goto 1 (eax updated to new atom->_value) */
 	: "=a"(eax), "+r"(val)
 	: "r"(&atom->_value)
 	: "cc", "memory"
@@ -202,7 +202,7 @@ inline int atom_xor(atom_t *atom, int val)
  * @param pos Bit position (starting from 0 for the LSB)
  * @return `true` the bit was clear *before* the operation
  */
-inline bool arch_atom_set_bit(atom_t *atom, int pos)
+inline bool atom_set_bit(atom_t *atom, int pos)
 {
 	int mask = 1 << pos;
 	int oldval = atom_or(atom, mask);
@@ -216,7 +216,7 @@ inline bool arch_atom_set_bit(atom_t *atom, int pos)
  * @param pos Bit position (starting from 0 for the LSB)
  * @return `true` if the bit was set *before* the operation
  */
-inline bool arch_atom_clr_bit(atom_t *atom, int pos)
+inline bool atom_clr_bit(atom_t *atom, int pos)
 {
 	int mask = 1 << pos;
 	int oldval = atom_and(atom, ~mask);

arch/x86/sys/atom.S

@@ -2,8 +2,16 @@
 
 #include <asm/common.h>
 
-/* int arch_atom_read(const atom_t *atom) */
-ASM_ENTRY(arch_atom_read)
+/*
+ * These routines are only really used if debugging is enabled, where everything
+ * is compiled with -O0.  Otherwise clang would just take the inline definitions
+ * from the header file (what an elegant way of creating bugs that only appear
+ * in optimized code!).  Therefore, we sacrifice a bit of performance for the
+ * sake of being nicer to gdb by creating frame pointers.
+ */
+
+/* int atom_read(const atom_t *atom) */
+ASM_ENTRY(atom_read)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -12,10 +20,10 @@ ASM_ENTRY(arch_atom_read)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_read)
+ASM_END(atom_read)
 
-/* int arch_atom_write(atom_t *atom, int val) */
-ASM_ENTRY(arch_atom_write)
+/* int atom_write(atom_t *atom, int val) */
+ASM_ENTRY(atom_write)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -28,10 +36,10 @@ ASM_ENTRY(arch_atom_write)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_write)
+ASM_END(atom_write)
 
-/* bool arch_atom_inc(atom_t *atom) */
-ASM_ENTRY(arch_atom_inc)
+/* bool atom_inc(atom_t *atom) */
+ASM_ENTRY(atom_inc)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -43,10 +51,10 @@ ASM_ENTRY(arch_atom_inc)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_inc)
+ASM_END(atom_inc)
 
-/* bool arch_atom_dec(atom_t *atom) */
-ASM_ENTRY(arch_atom_dec)
+/* bool atom_dec(atom_t *atom) */
+ASM_ENTRY(atom_dec)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -58,10 +66,10 @@ ASM_ENTRY(arch_atom_dec)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_dec)
+ASM_END(atom_dec)
 
-/* int arch_atom_add(atom_t *atom, int val) */
-ASM_ENTRY(arch_atom_add)
+/* int atom_add(atom_t *atom, int val) */
+ASM_ENTRY(atom_add)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -72,10 +80,10 @@ ASM_ENTRY(arch_atom_add)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_add)
+ASM_END(atom_add)
 
-/* int arch_atom_sub(atom_t *atom, int val) */
-ASM_ENTRY(arch_atom_sub)
+/* int atom_sub(atom_t *atom, int val) */
+ASM_ENTRY(atom_sub)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -89,10 +97,10 @@ ASM_ENTRY(arch_atom_sub)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_sub)
+ASM_END(atom_sub)
 
-/* int arch_atom_and(atom_t *atom, int val) */
-ASM_ENTRY(arch_atom_and)
+/* int atom_and(atom_t *atom, int val) */
+ASM_ENTRY(atom_and)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -107,10 +115,10 @@ ASM_ENTRY(arch_atom_and)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_and)
+ASM_END(atom_and)
 
-/* int arch_atom_or(atom_t *atom, int val) */
-ASM_ENTRY(arch_atom_or)
+/* int atom_or(atom_t *atom, int val) */
+ASM_ENTRY(atom_or)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -125,10 +133,10 @@ ASM_ENTRY(arch_atom_or)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_or)
+ASM_END(atom_or)
 
-/* int arch_atom_xor(atom_t *atom, int val) */
-ASM_ENTRY(arch_atom_xor)
+/* int atom_xor(atom_t *atom, int val) */
+ASM_ENTRY(atom_xor)
 	push	%ebp
 	mov	%esp, %ebp
 
@@ -143,10 +151,10 @@ ASM_ENTRY(arch_atom_xor)
 
 	pop	%ebp
 	ret
-ASM_END(arch_atom_xor)
+ASM_END(atom_xor)
 
-/* bool arch_atom_set_bit(atom_t *atom, int bit) */
-ASM_ENTRY(arch_atom_set_bit)
+/* bool atom_set_bit(atom_t *atom, int bit) */
+ASM_ENTRY(atom_set_bit)
 	push	%ebp
 	mov	%esp, %ebp
 	push	%ebx
@@ -171,10 +179,10 @@ ASM_ENTRY(arch_atom_set_bit)
 	pop	%ebx
 	pop	%ebp
 	ret
-ASM_END(arch_atom_set_bit)
+ASM_END(atom_set_bit)
 
-/* bool arch_atom_clr_bit(atom_t *atom, int bit) */
-ASM_ENTRY(arch_atom_clr_bit)
+/* bool atom_clr_bit(atom_t *atom, int bit) */
+ASM_ENTRY(atom_clr_bit)
 	push	%ebp
 	mov	%esp, %ebp
 	push	%ebx
@@ -199,7 +207,7 @@ ASM_ENTRY(arch_atom_clr_bit)
 	pop	%ebx
 	pop	%ebp
 	ret
-ASM_END(arch_atom_clr_bit)
+ASM_END(atom_clr_bit)
 
 /*
  * This file is part of GayBSD.

include/gay/mutex.h

@@ -12,7 +12,7 @@ typedef struct {
 } spin_t;
 
 #define SPIN(name) struct spin name = {	\
-	.lock = { ._value = 0 },	\
+	.lock = ATOM_DEFINE(0),		\
 }
 
 void spin_init(spin_t *spin);