From: Graf Yang <graf.yang@analog.com>
Date: Thu, 7 Jan 2010 06:57:30 +0000 (+0000)
Subject: Blackfin: SMP: make all barriers handle cache issues
X-Git-Tag: firefly_0821_release~7613^2~1615^2~3
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=943aee0c685d0563228d5a2ad9c8394ad0300fb5;p=firefly-linux-kernel-4.4.55.git

Blackfin: SMP: make all barriers handle cache issues

When suspending/resuming, the common task freezing code will run in
parallel and freeze processes on each core.  This is because the code
uses the non-smp version of memory barriers (as well it should).

The Blackfin smp barrier logic at the moment contains the cache sync
logic, but the non-smp barriers do not.  This is incorrect as Rafel
summarized:
> ...
> The existing memory barriers are SMP barriers too, but they are more
> than _just_ SMP barriers.  At least that's how it is _supposed_ to be
> (eg. rmb() is supposed to be stronger than smp_rmb()).
> ...
> However, looking at the blackfin's definitions of SMP barriers I see
> that it uses extra stuff that should _also_ be used in the definitions
> of the mandatory barriers.
> ...

URL: http://lkml.org/lkml/2011/4/13/11
LKML-Reference: <BANLkTi=F-C-vwX4PGGfbkdTBw3OWL-twfg@mail.gmail.com>
Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---

diff --git a/arch/blackfin/include/asm/system.h b/arch/blackfin/include/asm/system.h
index 19e2c7c3e63a..44bd0cced725 100644
--- a/arch/blackfin/include/asm/system.h
+++ b/arch/blackfin/include/asm/system.h
@@ -19,11 +19,11 @@
  * Force strict CPU ordering.
  */
 #define nop()  __asm__ __volatile__ ("nop;\n\t" : : )
-#define mb()   __asm__ __volatile__ (""   : : : "memory")
-#define rmb()  __asm__ __volatile__ (""   : : : "memory")
-#define wmb()  __asm__ __volatile__ (""   : : : "memory")
-#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
-#define read_barrier_depends() 		do { } while(0)
+#define smp_mb()  mb()
+#define smp_rmb() rmb()
+#define smp_wmb() wmb()
+#define set_mb(var, value) do { var = value; mb(); } while (0)
+#define smp_read_barrier_depends()	read_barrier_depends()
 
 #ifdef CONFIG_SMP
 asmlinkage unsigned long __raw_xchg_1_asm(volatile void *ptr, unsigned long value);
@@ -37,16 +37,16 @@ asmlinkage unsigned long __raw_cmpxchg_4_asm(volatile void *ptr,
 					unsigned long new, unsigned long old);
 
 #ifdef __ARCH_SYNC_CORE_DCACHE
-# define smp_mb()	do { barrier(); smp_check_barrier(); smp_mark_barrier(); } while (0)
-# define smp_rmb()	do { barrier(); smp_check_barrier(); } while (0)
-# define smp_wmb()	do { barrier(); smp_mark_barrier(); } while (0)
-#define smp_read_barrier_depends()	do { barrier(); smp_check_barrier(); } while (0)
-
+/* Force Core data cache coherence */
+# define mb()	do { barrier(); smp_check_barrier(); smp_mark_barrier(); } while (0)
+# define rmb()	do { barrier(); smp_check_barrier(); } while (0)
+# define wmb()	do { barrier(); smp_mark_barrier(); } while (0)
+# define read_barrier_depends()	do { barrier(); smp_check_barrier(); } while (0)
 #else
-# define smp_mb()	barrier()
-# define smp_rmb()	barrier()
-# define smp_wmb()	barrier()
-#define smp_read_barrier_depends()	barrier()
+# define mb()	barrier()
+# define rmb()	barrier()
+# define wmb()	barrier()
+# define read_barrier_depends()	do { } while (0)
 #endif
 
 static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
@@ -99,10 +99,10 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 
 #else /* !CONFIG_SMP */
 
-#define smp_mb()	barrier()
-#define smp_rmb()	barrier()
-#define smp_wmb()	barrier()
-#define smp_read_barrier_depends()	do { } while(0)
+#define mb()	barrier()
+#define rmb()	barrier()
+#define wmb()	barrier()
+#define read_barrier_depends()	do { } while (0)
 
 struct __xchg_dummy {
 	unsigned long a[100];