[PATCH v2] sparc: Provide cmpxchg64 for 32-bit builds

From: Guenter Roeck
Date: Wed Oct 25 2017 - 22:52:05 EST


Fix the following build error, seen when building sparc32:allmodconfig.

drivers/net/ethernet/intel/i40e/i40e_ethtool.c:
In function 'i40e_set_priv_flags':
drivers/net/ethernet/intel/i40e/i40e_ethtool.c:4150:2: error:
implicit declaration of function 'cmpxchg64'

Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
v2: Actually implement cmpxchg64 with code snippet provided by Dave Miller
Note: I am aware that this doesn't pass checkpatch; I found it more
important to be in line with __cmpxchg_u32().

arch/sparc/include/asm/cmpxchg_32.h | 2 ++
arch/sparc/lib/atomic32.c | 14 ++++++++++++++
2 files changed, 16 insertions(+)

diff --git a/arch/sparc/include/asm/cmpxchg_32.h b/arch/sparc/include/asm/cmpxchg_32.h
index 83ffb83c5397..7f95d3ca20e2 100644
--- a/arch/sparc/include/asm/cmpxchg_32.h
+++ b/arch/sparc/include/asm/cmpxchg_32.h
@@ -62,6 +62,8 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
(unsigned long)_n_, sizeof(*(ptr))); \
})

+extern u64 cmpxchg64(u64 *ptr, u64 old, u64 new);
+
#include <asm-generic/cmpxchg-local.h>

/*
diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index 2c373329d5cb..41601eb540e7 100644
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -172,6 +172,20 @@ unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
}
EXPORT_SYMBOL(__cmpxchg_u32);

+u64 cmpxchg64(u64 *ptr, u64 old, u64 new)
+{
+ unsigned long flags;
+ u64 prev;
+
+ spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
+ if ((prev = *ptr) == old)
+ *ptr = new;
+ spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
+
+ return prev;
+}
+EXPORT_SYMBOL(cmpxchg64);
+
unsigned long __xchg_u32(volatile u32 *ptr, u32 new)
{
unsigned long flags;
--
2.7.4