RDS: Use spinlock to protect 64b value update on 32b archs

We have a 64bit value that needs to be set atomically.
This is easy and quick on all 64bit archs, and can also be done
on x86/32 with set_64bit() (uses cmpxchg8b). However other
32b archs don't have this.

I actually changed this to the current state in preparation for
mainline because the old way (using a spinlock on 32b) resulted in
unsightly #ifdefs in the code. But obviously, being correct takes
precedence.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 9 deletions

diff --git a/net/rds/ib.h b/net/rds/ib.h
index c08ffffb3164..069206cae733 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -108,7 +108,12 @@ struct rds_ib_connection {
 
         /* sending acks */
         unsigned long           i_ack_flags;
+#ifdef KERNEL_HAS_ATOMIC64
+        atomic64_t              i_ack_next;     /* next ACK to send */
+#else
+        spinlock_t              i_ack_lock;     /* protect i_ack_next */
         u64                     i_ack_next;     /* next ACK to send */
+#endif
         struct rds_header       *i_ack;
         struct ib_send_wr       i_ack_wr;
         struct ib_sge           i_ack_sge;
@@ -363,13 +368,4 @@ rds_ib_data_sge(struct rds_ib_connection *ic, struct ib_sge *sge)
         return &sge[1];
 }
 
-static inline void rds_ib_set_64bit(u64 *ptr, u64 val)
-{
-#if BITS_PER_LONG == 64
-        *ptr = val;
-#else
-        set_64bit(ptr, val);
-#endif
-}
-
 #endif