[RFC][PATCH 2.4 3/4] inotify 0.22 2.4.x backport - atomic_inc_return

[RFC][PATCH 2.4 3/4] inotify 0.22 2.4.x backport - atomic_inc_return

[Mihai Rusu]

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Hi

Backported atomic_inc_return() from 2.6.11 for x86. Needed by inotify.c.
I have not backported for other architectures as I don't have access to
such devices and I could not test. It should be easy to do that tho.
This also means that this inotify backport currently only works for x86.

-- 
Mihai Rusu
Linux System Development

Schlund + Partner AG   Tel         : +40-21-231-2544
Str Mircea Eliade 18   EMail       : dizzy@schlund.ro
Sect 1, Bucuresti
71295, Romania



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 atomic.h |   34 ++++++++++++++++++++++++++++++++++
 1 files changed, 34 insertions(+)


diff -uNr linux-2.4.30.orig/include/asm-i386/atomic.h linux-2.4.30/include/asm-i386/atomic.h
--- linux-2.4.30.orig/include/asm-i386/atomic.h	2001-11-22 21:46:18.000000000 +0200
+++ linux-2.4.30/include/asm-i386/atomic.h	2005-05-09 11:58:56.000000000 +0300
@@ -186,6 +186,40 @@
 	return c;
 }
 
+/**
+ * atomic_add_return - add and return
+ * @v: pointer of type atomic_t
+ * @i: integer value to add
+ *
+ * Atomically adds @i to @v and returns @i + @v
+ */
+static __inline__ int atomic_add_return(int i, atomic_t *v)
+{
+        int __i;
+#ifdef CONFIG_M386
+        if(unlikely(boot_cpu_data.x86==3))
+                goto no_xadd;
+#endif
+        /* Modern 486+ processor */
+        __i = i;
+        __asm__ __volatile__(
+                LOCK "xaddl %0, %1;"
+                :"=r"(i)
+                :"m"(v->counter), "0"(i));
+        return i + __i;
+
+#ifdef CONFIG_M386
+no_xadd: /* Legacy 386 processor */
+        local_irq_disable();
+        __i = atomic_read(v);
+        atomic_set(v, i + __i);
+        local_irq_enable();
+        return i + __i;
+#endif
+}
+
+#define atomic_inc_return(v)  (atomic_add_return(1,v))
+
 /* These are x86-specific, used by some header files */
 #define atomic_clear_mask(mask, addr) \
 __asm__ __volatile__(LOCK "andl %0,%1" \