ring-buffer: typecast cmpxchg to fix PowerPC warning
The cmpxchg used by PowerPC does the following:
({ \
__typeof__(*(ptr)) _o_ = (o); \
__typeof__(*(ptr)) _n_ = (n); \
(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
(unsigned long)_n_, sizeof(*(ptr))); \
})
This does a type check of *ptr to both o and n.
Unfortunately, the code in ring-buffer.c assigns longs to pointers
and pointers to longs and causes a warning on PowerPC:
ring_buffer.c: In function 'rb_head_page_set':
ring_buffer.c:704: warning: initialization makes pointer from integer without a cast
ring_buffer.c:704: warning: initialization makes pointer from integer without a cast
ring_buffer.c: In function 'rb_head_page_replace':
ring_buffer.c:797: warning: initialization makes integer from pointer without a cast
This patch adds the typecasts inside cmpxchg to annotate that a long is
being cast to a pointer and a pointer is being casted to a long and this
removes the PowerPC warnings.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 8786c35..6eef389 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -701,8 +701,8 @@
val &= ~RB_FLAG_MASK;
- ret = (unsigned long)cmpxchg(&list->next,
- val | old_flag, val | new_flag);
+ ret = cmpxchg((unsigned long *)&list->next,
+ val | old_flag, val | new_flag);
/* check if the reader took the page */
if ((ret & ~RB_FLAG_MASK) != val)
@@ -794,7 +794,7 @@
val = *ptr & ~RB_FLAG_MASK;
val |= RB_PAGE_HEAD;
- ret = cmpxchg(ptr, val, &new->list);
+ ret = cmpxchg(ptr, val, (unsigned long)&new->list);
return ret == val;
}