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Subject: Re: [PATCH] Unwire set/get_robust_list
From: David Woodhouse <dwmw2@infradead.org>
To: Andreas Schwab <schwab@suse.de>
In-Reply-To: <jeodtvfn4x.fsf@sykes.suse.de>
References: <jeodtvfn4x.fsf@sykes.suse.de>
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Date: Mon, 04 Sep 2006 15:32:27 -0700
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On Mon, 2006-09-04 at 21:27 +0200, Andreas Schwab wrote:
> The syscalls set/get_robust_list must not be wired up until
> futex_atomic_cmpxchg_inatomic is implemented.  Otherwise the kernel will
> hang in handle_futex_death.

Something like this? 

Untested-but-otherwise-Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/include/asm-powerpc/futex.h b/include/asm-powerpc/futex.h
index f1b3c00..e8ff12c 100644
--- a/include/asm-powerpc/futex.h
+++ b/include/asm-powerpc/futex.h
@@ -84,7 +84,30 @@ static inline int futex_atomic_op_inuser
 static inline int
 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 {
-	return -ENOSYS;
+	int prev;
+
+        __asm__ __volatile__ (
+        LWSYNC_ON_SMP
+"1:     lwarx   %0,0,%2         # futex_atomic_cmpxchg_inatomic\n\
+        cmpw    0,%0,%3\n\
+        bne-    3f\n"
+        PPC405_ERR77(0,%2)
+"2:     stwcx.  %4,0,%2\n\
+        bne-    1b\n"
+        ISYNC_ON_SMP
+"3:	.section .fixup,\"ax\"\n\
+4:	li	%0,%5\n\
+	b	3b\n\
+	.previous\n\
+	.section __ex_table,\"a\"\n\
+	.align 3\n\
+	" PPC_LONG "1b,4b,2b,4b\n\
+	.previous" \
+        : "=&r" (prev), "+m" (*uaddr)
+        : "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT)
+        : "cc", "memory");
+
+        return prev;
 }
 
 #endif /* __KERNEL__ */

-- 
dwmw2