[058/114] sparc64: Fix rwsem constant bug leading to hangs.

[Greg KH]

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------


From: David S. Miller <davem@xxxxxxxxxxxxx>

[ Upstream commit ef201bebe5afc91a2b99b45dacc8c6dd88ca9e58 ]

As noticed by Linus, it is critical that some of the
rwsem constants be signed.  Yet, hex constants are
unsigned unless explicitly casted or negated.

The most critical one is RWSEM_WAITING_BIAS.

This bug was exacerbated by commit
424acaaeb3a3932d64a9b4bd59df6cf72c22d8f3 ("rwsem: wake queued readers
when writer blocks on active read lock")

Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 arch/sparc/include/asm/rwsem-const.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/sparc/include/asm/rwsem-const.h
+++ b/arch/sparc/include/asm/rwsem-const.h
@@ -5,7 +5,7 @@
 #define RWSEM_UNLOCKED_VALUE		0x00000000
 #define RWSEM_ACTIVE_BIAS		0x00000001
 #define RWSEM_ACTIVE_MASK		0x0000ffff
-#define RWSEM_WAITING_BIAS		0xffff0000
+#define RWSEM_WAITING_BIAS		(-0x00010000)
 #define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
 #define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
 


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