[PATCH 5/18] iseries_veth: Remove redundant message stack lock

From: Michael Ellerman
Date: Wed Aug 31 2005 - 20:32:05 EST


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@xxxxxxxxxxxxxx>
---

drivers/net/iseries_veth.c | 12 +++---------
1 files changed, 3 insertions(+), 9 deletions(-)

Index: veth-dev2/drivers/net/iseries_veth.c
===================================================================
--- veth-dev2.orig/drivers/net/iseries_veth.c
+++ veth-dev2/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
#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;
-
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