Redefine ATOMIC_INIT and ATOMIC64_INIT to drop the casts

commit a119365586b0130dfea06457f584953e0ff6481d upstream.

The following build error occured during a ia64 build with
swap-over-NFS patches applied.

net/core/sock.c:274:36: error: initializer element is not constant
net/core/sock.c:274:36: error: (near initialization for 'memalloc_socks')
net/core/sock.c:274:36: error: initializer element is not constant

This is identical to a parisc build error. Fengguang Wu, Mel Gorman
and James Bottomley did all the legwork to track the root cause of
the problem. This fix and entire commit log is shamelessly copied
from them with one extra detail to change a dubious runtime use of
ATOMIC_INIT() to atomic_set() in drivers/char/mspec.c

Dave Anglin says:
> Here is the line in sock.i:
>
> struct static_key memalloc_socks = ((struct static_key) { .enabled =
> ((atomic_t) { (0) }) });

The above line contains two compound literals.  It also uses a designated
initializer to initialize the field enabled.  A compound literal is not a
constant expression.

The location of the above statement isn't fully clear, but if a compound
literal occurs outside the body of a function, the initializer list must
consist of constant expressions.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/ia64/include/asm/atomic.h b/arch/ia64/include/asm/atomic.h
index 446881439675934b295d39fcd0519fce19f6ffdd..6fcc9a081e4c5ed3a8073a2beb3438fa0801ed97 100644 (file)
--- a/arch/ia64/include/asm/atomic.h
+++ b/arch/ia64/include/asm/atomic.h
@@ -18,8 +18,8 @@
 #include <asm/system.h>
 
 
-#define ATOMIC_INIT(i)         ((atomic_t) { (i) })
-#define ATOMIC64_INIT(i)       ((atomic64_t) { (i) })
+#define ATOMIC_INIT(i)         { (i) }
+#define ATOMIC64_INIT(i)       { (i) }
 
 #define atomic_read(v)         (*(volatile int *)&(v)->counter)
 #define atomic64_read(v)       (*(volatile long *)&(v)->counter)

diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
index 25d139c9dbeddd86440847f3ced302950883ef98..579051ce8545a42b85f1c9ca8a496066dbeafe64 100644 (file)
--- a/drivers/char/mspec.c
+++ b/drivers/char/mspec.c
@@ -284,7 +284,7 @@ mspec_mmap(struct file *file, struct vm_area_struct *vma,
        vdata->flags = flags;
        vdata->type = type;
        spin_lock_init(&vdata->lock);
-       vdata->refcnt = ATOMIC_INIT(1);
+       atomic_set(&vdata->refcnt, 1);
        vma->vm_private_data = vdata;
 
        vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);