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authorAndy Grover <andy.grover@oracle.com>2009-04-01 08:20:20 +0000
committerDavid S. Miller <davem@davemloft.net>2009-04-02 00:52:22 -0700
commit8cbd9606a6367c221a7bbcc47f3ab1a8c31b6437 (patch)
tree9ff2adf88be32383fd59dc133f1cd6670b9ee815 /net
parent745cbccac3fe8cead529a1b3358e1e86a1505bfa (diff)
downloadlinux-2.6.38-lt-ux500-8cbd9606a6367c221a7bbcc47f3ab1a8c31b6437.tar.gz
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>
Diffstat (limited to 'net')
-rw-r--r--net/rds/ib.h14
-rw-r--r--net/rds/ib_cm.c9
-rw-r--r--net/rds/ib_recv.c37
-rw-r--r--net/rds/iw.h14
-rw-r--r--net/rds/iw_cm.c9
-rw-r--r--net/rds/iw_recv.c37
-rw-r--r--net/rds/rds.h4
7 files changed, 100 insertions, 24 deletions
diff --git a/net/rds/ib.h b/net/rds/ib.h
index c08ffffb316..069206cae73 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
diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 889ab044135..f8e40e1a603 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -636,7 +636,11 @@ void rds_ib_conn_shutdown(struct rds_connection *conn)
/* Clear the ACK state */
clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
- rds_ib_set_64bit(&ic->i_ack_next, 0);
+#ifdef KERNEL_HAS_ATOMIC64
+ atomic64_set(&ic->i_ack_next, 0);
+#else
+ ic->i_ack_next = 0;
+#endif
ic->i_ack_recv = 0;
/* Clear flow control state */
@@ -669,6 +673,9 @@ int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp)
INIT_LIST_HEAD(&ic->ib_node);
mutex_init(&ic->i_recv_mutex);
+#ifndef KERNEL_HAS_ATOMIC64
+ spin_lock_init(&ic->i_ack_lock);
+#endif
/*
* rds_ib_conn_shutdown() waits for these to be emptied so they
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 5061b550216..36d931573ff 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -395,10 +395,37 @@ void rds_ib_recv_init_ack(struct rds_ib_connection *ic)
* room for it beyond the ring size. Send completion notices its special
* wr_id and avoids working with the ring in that case.
*/
+#ifndef KERNEL_HAS_ATOMIC64
static void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq,
int ack_required)
{
- rds_ib_set_64bit(&ic->i_ack_next, seq);
+ unsigned long flags;
+
+ spin_lock_irqsave(&ic->i_ack_lock, flags);
+ ic->i_ack_next = seq;
+ if (ack_required)
+ set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
+ spin_unlock_irqrestore(&ic->i_ack_lock, flags);
+}
+
+static u64 rds_ib_get_ack(struct rds_ib_connection *ic)
+{
+ unsigned long flags;
+ u64 seq;
+
+ clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
+
+ spin_lock_irqsave(&ic->i_ack_lock, flags);
+ seq = ic->i_ack_next;
+ spin_unlock_irqrestore(&ic->i_ack_lock, flags);
+
+ return seq;
+}
+#else
+static void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq,
+ int ack_required)
+{
+ atomic64_set(&ic->i_ack_next, seq);
if (ack_required) {
smp_mb__before_clear_bit();
set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
@@ -410,8 +437,10 @@ static u64 rds_ib_get_ack(struct rds_ib_connection *ic)
clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
smp_mb__after_clear_bit();
- return ic->i_ack_next;
+ return atomic64_read(&ic->i_ack_next);
}
+#endif
+
static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credits)
{
@@ -464,6 +493,10 @@ static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credi
* - i_ack_next, which is the last sequence number we received
*
* Potentially, send queue and receive queue handlers can run concurrently.
+ * It would be nice to not have to use a spinlock to synchronize things,
+ * but the one problem that rules this out is that 64bit updates are
+ * not atomic on all platforms. Things would be a lot simpler if
+ * we had atomic64 or maybe cmpxchg64 everywhere.
*
* Reconnecting complicates this picture just slightly. When we
* reconnect, we may be seeing duplicate packets. The peer
diff --git a/net/rds/iw.h b/net/rds/iw.h
index 70eb948f42f..b4fb2725289 100644
--- a/net/rds/iw.h
+++ b/net/rds/iw.h
@@ -131,7 +131,12 @@ struct rds_iw_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;
@@ -391,13 +396,4 @@ rds_iw_data_sge(struct rds_iw_connection *ic, struct ib_sge *sge)
return &sge[1];
}
-static inline void rds_iw_set_64bit(u64 *ptr, u64 val)
-{
-#if BITS_PER_LONG == 64
- *ptr = val;
-#else
- set_64bit(ptr, val);
-#endif
-}
-
#endif
diff --git a/net/rds/iw_cm.c b/net/rds/iw_cm.c
index 0ffaa3e97ad..a416b0d492b 100644
--- a/net/rds/iw_cm.c
+++ b/net/rds/iw_cm.c
@@ -659,7 +659,11 @@ void rds_iw_conn_shutdown(struct rds_connection *conn)
/* Clear the ACK state */
clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
- rds_iw_set_64bit(&ic->i_ack_next, 0);
+#ifdef KERNEL_HAS_ATOMIC64
+ atomic64_set(&ic->i_ack_next, 0);
+#else
+ ic->i_ack_next = 0;
+#endif
ic->i_ack_recv = 0;
/* Clear flow control state */
@@ -693,6 +697,9 @@ int rds_iw_conn_alloc(struct rds_connection *conn, gfp_t gfp)
INIT_LIST_HEAD(&ic->iw_node);
mutex_init(&ic->i_recv_mutex);
+#ifndef KERNEL_HAS_ATOMIC64
+ spin_lock_init(&ic->i_ack_lock);
+#endif
/*
* rds_iw_conn_shutdown() waits for these to be emptied so they
diff --git a/net/rds/iw_recv.c b/net/rds/iw_recv.c
index a1931f0027a..fde470fa50d 100644
--- a/net/rds/iw_recv.c
+++ b/net/rds/iw_recv.c
@@ -395,10 +395,37 @@ void rds_iw_recv_init_ack(struct rds_iw_connection *ic)
* room for it beyond the ring size. Send completion notices its special
* wr_id and avoids working with the ring in that case.
*/
+#ifndef KERNEL_HAS_ATOMIC64
static void rds_iw_set_ack(struct rds_iw_connection *ic, u64 seq,
int ack_required)
{
- rds_iw_set_64bit(&ic->i_ack_next, seq);
+ unsigned long flags;
+
+ spin_lock_irqsave(&ic->i_ack_lock, flags);
+ ic->i_ack_next = seq;
+ if (ack_required)
+ set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
+ spin_unlock_irqrestore(&ic->i_ack_lock, flags);
+}
+
+static u64 rds_iw_get_ack(struct rds_iw_connection *ic)
+{
+ unsigned long flags;
+ u64 seq;
+
+ clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
+
+ spin_lock_irqsave(&ic->i_ack_lock, flags);
+ seq = ic->i_ack_next;
+ spin_unlock_irqrestore(&ic->i_ack_lock, flags);
+
+ return seq;
+}
+#else
+static void rds_iw_set_ack(struct rds_iw_connection *ic, u64 seq,
+ int ack_required)
+{
+ atomic64_set(&ic->i_ack_next, seq);
if (ack_required) {
smp_mb__before_clear_bit();
set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
@@ -410,8 +437,10 @@ static u64 rds_iw_get_ack(struct rds_iw_connection *ic)
clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
smp_mb__after_clear_bit();
- return ic->i_ack_next;
+ return atomic64_read(&ic->i_ack_next);
}
+#endif
+
static void rds_iw_send_ack(struct rds_iw_connection *ic, unsigned int adv_credits)
{
@@ -464,6 +493,10 @@ static void rds_iw_send_ack(struct rds_iw_connection *ic, unsigned int adv_credi
* - i_ack_next, which is the last sequence number we received
*
* Potentially, send queue and receive queue handlers can run concurrently.
+ * It would be nice to not have to use a spinlock to synchronize things,
+ * but the one problem that rules this out is that 64bit updates are
+ * not atomic on all platforms. Things would be a lot simpler if
+ * we had atomic64 or maybe cmpxchg64 everywhere.
*
* Reconnecting complicates this picture just slightly. When we
* reconnect, we may be seeing duplicate packets. The peer
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 06040070497..619f0a30a4e 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -28,6 +28,10 @@
*/
#define RDS_PORT 18634
+#ifdef ATOMIC64_INIT
+#define KERNEL_HAS_ATOMIC64
+#endif
+
#ifdef DEBUG
#define rdsdebug(fmt, args...) pr_debug("%s(): " fmt, __func__ , ##args)
#else