[ltt-dev] [PATCH] uatomic: use generic-size macros for common implementation of atomic ops

[Paolo Bonzini]

The definition of _uatomic_cmpxchg is different in x86 and other architectures.
For x86 it is a 4-argument macro, for other architectures it is a 3-argument
function.  This patch makes it easier to implement atomic operations
incrementally (first as a generic version and then in machine-specific code),
which aids testing and bisectability.

Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
---
	Examples will come once I'll be back from my holidays. :P

 urcu/uatomic_generic.h |   24 ++++++++++++++++--------
 1 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/urcu/uatomic_generic.h b/urcu/uatomic_generic.h
index cef58f3..337fe40 100644
--- a/urcu/uatomic_generic.h
+++ b/urcu/uatomic_generic.h
@@ -395,7 +395,8 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned char *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, old + val, 1);
+			oldt = uatomic_cmpxchg((unsigned char *)addr,
+                                               old, old + val);
 		} while (oldt != old);
 
 		return old + val;
@@ -409,7 +410,8 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned short *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, old + val, 2);
+			oldt = uatomic_cmpxchg((unsigned short *)addr,
+                                               old, old + val);
 		} while (oldt != old);
 
 		return old + val;
@@ -422,7 +424,8 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned int *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, old + val, 4);
+			oldt = uatomic_cmpxchg((unsigned int *)addr,
+                                               old, old + val);
 		} while (oldt != old);
 
 		return old + val;
@@ -435,7 +438,8 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned long *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, old + val, 8);
+			oldt = uatomic_cmpxchg((unsigned long *)addr,
+                                               old, old + val);
 		} while (oldt != old);
 
 		return old + val;
@@ -467,7 +471,8 @@ unsigned long _uatomic_exchange(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned char *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, val, 1);
+			oldt = uatomic_cmpxchg((unsigned char *)addr,
+                                               old, val);
 		} while (oldt != old);
 
 		return old;
@@ -481,7 +486,8 @@ unsigned long _uatomic_exchange(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned short *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, val, 2);
+			oldt = uatomic_cmpxchg((unsigned short *)addr,
+                                               old, val);
 		} while (oldt != old);
 
 		return old;
@@ -494,7 +500,8 @@ unsigned long _uatomic_exchange(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned int *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, val, 4);
+			oldt = uatomic_cmpxchg((unsigned int *)addr,
+                                               old, val);
 		} while (oldt != old);
 
 		return old;
@@ -507,7 +514,8 @@ unsigned long _uatomic_exchange(void *addr, unsigned long val, int len)
 		oldt = uatomic_read((unsigned long *)addr);
 		do {
 			old = oldt;
-			oldt = _uatomic_cmpxchg(addr, old, val, 8);
+			oldt = uatomic_cmpxchg((unsigned long *)addr,
+                                               old, val);
 		} while (oldt != old);
 
 		return old;
-- 
1.7.4.4