[PATCH] iseries_veth: Remove redundant message stack lock

The iseries_veth driver keeps a stack of messages for each connection
and a lock to protect the stack. However there is also a per-connection lock
which makes the message stack lock redundant.

Remove the message stack lock and document the fact that callers of the
stack-manipulation functions must hold the connection's lock.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 3 insertions, 9 deletions

diff --git a/drivers/net/iseries_veth.c b/drivers/net/iseries_veth.c
index 74ee937c4606..231b2d2d3264 100644
--- a/drivers/net/iseries_veth.c
+++ b/drivers/net/iseries_veth.c
@@ -143,7 +143,6 @@ struct veth_lpar_connection {
         struct VethCapData remote_caps;
         u32 ack_timeout;
 
-        spinlock_t msg_stack_lock;
         struct veth_msg *msg_stack_head;
 };
 
@@ -190,27 +189,23 @@ static void veth_timed_ack(unsigned long connectionPtr);
 #define veth_debug(fmt, args...) do {} while (0)
 #endif
 
+/* You must hold the connection's lock when you call this function. */
 static inline void veth_stack_push(struct veth_lpar_connection *cnx,
                                    struct veth_msg *msg)
 {
-        unsigned long flags;
-
-        spin_lock_irqsave(&cnx->msg_stack_lock, flags);
         msg->next = cnx->msg_stack_head;
         cnx->msg_stack_head = msg;
-        spin_unlock_irqrestore(&cnx->msg_stack_lock, flags);
 }
 
+/* You must hold the connection's lock when you call this function. */
 static inline struct veth_msg *veth_stack_pop(struct veth_lpar_connection *cnx)
 {
-        unsigned long flags;
         struct veth_msg *msg;
 
-        spin_lock_irqsave(&cnx->msg_stack_lock, flags);
         msg = cnx->msg_stack_head;
         if (msg)
                 cnx->msg_stack_head = cnx->msg_stack_head->next;
-        spin_unlock_irqrestore(&cnx->msg_stack_lock, flags);
+
         return msg;
 }
 
@@ -645,7 +640,6 @@ static int veth_init_connection(u8 rlp)
 
         cnx->msgs = msgs;
         memset(msgs, 0, VETH_NUMBUFFERS * sizeof(struct veth_msg));
-        spin_lock_init(&cnx->msg_stack_lock);
 
         for (i = 0; i < VETH_NUMBUFFERS; i++) {
                 msgs[i].token = i;