* [PATCH 21/24] make atomic_read() behave consistently on v850
@ 2007-08-09 14:16 Chris Snook
0 siblings, 0 replies; only message in thread
From: Chris Snook @ 2007-08-09 14:16 UTC (permalink / raw)
To: linux-kernel, linux-arch, torvalds
Cc: netdev, akpm, ak, heiko.carstens, davem, schwidefsky, wensong,
horms, wjiang, cfriesen, zlynx, rpjday, jesper.juhl
From: Chris Snook <csnook@redhat.com>
Make atomic_read() volatile on v850. This ensures that busy-waiting
for an interrupt handler to change an atomic_t won't get compiled to an
infinite loop, consistent with SMP architectures.
Signed-off-by: Chris Snook <csnook@redhat.com>
--- linux-2.6.23-rc2-orig/include/asm-v850/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-v850/atomic.h 2007-08-09 07:50:15.000000000 -0400
@@ -27,7 +27,11 @@ typedef struct { int counter; } atomic_t
#ifdef __KERNEL__
-#define atomic_read(v) ((v)->counter)
+/*
+ * Casting to volatile here minimizes the need for barriers,
+ * without having to declare the type itself as volatile.
+ */
+#define atomic_read(v) (*(volatile int *)&(v)->counter)
#define atomic_set(v,i) (((v)->counter) = (i))
static inline int atomic_add_return (int i, volatile atomic_t *v)
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2007-08-09 14:16 UTC | newest]
Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2007-08-09 14:16 [PATCH 21/24] make atomic_read() behave consistently on v850 Chris Snook
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).