locking/atomic: net: use linux/atomic.h for xchg & cmpxchg

As xchg*() and cmpxchg*() may be instrumented by atomic-instrumented.h,
it's necessary to include <linux/atomic.h> to use these, rather than
<asm/cmpxchg.h>, which is effectively an arch-internal header.

In a couple of places we include <asm/cmpxchg.h>, but get away with this
as <linux/atomic.h> gets pulled in inidrectly by another include. Before
we convert more architectures to use atomic-instrumented.h, let's fix
these up to use <linux/atomic.h> so that we don't make things more
fragile.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210525140232.53872-3-mark.rutland@arm.com

net/core/filter.c

@@ -17,6 +17,7 @@
  * Kris Katterjohn - Added many additional checks in bpf_check_classic()
  */
 
+#include <linux/atomic.h>
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/mm.h>
@@ -41,7 +42,6 @@
 #include <linux/timer.h>
 #include <linux/uaccess.h>
 #include <asm/unaligned.h>
-#include <asm/cmpxchg.h>
 #include <linux/filter.h>
 #include <linux/ratelimit.h>
 #include <linux/seccomp.h>

net/sunrpc/xprtmultipath.c

@@ -7,13 +7,13 @@
  * Trond Myklebust <trond.myklebust@primarydata.com>
  *
  */
+#include <linux/atomic.h>
 #include <linux/types.h>
 #include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
 #include <linux/slab.h>
-#include <asm/cmpxchg.h>
 #include <linux/spinlock.h>
 #include <linux/sunrpc/xprt.h>
 #include <linux/sunrpc/addr.h>