[PATCH 04/14] aoe: use a kernel thread for transmissions

From: Ed Cashin
Date: Thu Aug 23 2012 - 14:45:18 EST


The dev_queue_xmit function needs to have interrupts enabled, so the
most simple way to get the locking right but still fulfill that
requirement is to use a process that can call dev_queue_xmit serially
over queued transmissions.

Signed-off-by: Ed Cashin <ecashin@xxxxxxxxxx>
---
drivers/block/aoe/aoe.h | 2 ++
drivers/block/aoe/aoecmd.c | 4 ++--
drivers/block/aoe/aoenet.c | 37 ++++++++++++++++++++++++++++++++++++-
3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/block/aoe/aoe.h b/drivers/block/aoe/aoe.h
index 8c4f6d9..d0087de1 100644
--- a/drivers/block/aoe/aoe.h
+++ b/drivers/block/aoe/aoe.h
@@ -210,6 +210,8 @@ struct sk_buff *aoecmd_ata_id(struct aoedev *);
void aoe_freetframe(struct frame *);
void aoe_flush_iocq(void);
void aoe_end_request(struct aoedev *, struct request *, int);
+int aoe_ktstart(struct ktstate *k);
+void aoe_ktstop(struct ktstate *k);

int aoedev_init(void);
void aoedev_exit(void);
diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index e7df343..92eb28a 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -1117,14 +1117,14 @@ kthread(void *vp)
return 0;
}

-static void
+void
aoe_ktstop(struct ktstate *k)
{
kthread_stop(k->task);
wait_for_completion(&k->rendez);
}

-static int
+int
aoe_ktstart(struct ktstate *k)
{
struct task_struct *task;
diff --git a/drivers/block/aoe/aoenet.c b/drivers/block/aoe/aoenet.c
index 000eff2..5f43710 100644
--- a/drivers/block/aoe/aoenet.c
+++ b/drivers/block/aoe/aoenet.c
@@ -33,6 +33,9 @@ static char aoe_iflist[IFLISTSZ];
module_param_string(aoe_iflist, aoe_iflist, IFLISTSZ, 0600);
MODULE_PARM_DESC(aoe_iflist, "aoe_iflist=\"dev1 [dev2 ...]\"");

+static wait_queue_head_t txwq;
+static struct ktstate kts;
+
#ifndef MODULE
static int __init aoe_iflist_setup(char *str)
{
@@ -44,6 +47,23 @@ static int __init aoe_iflist_setup(char *str)
__setup("aoe_iflist=", aoe_iflist_setup);
#endif

+static spinlock_t txlock;
+static struct sk_buff_head skbtxq;
+
+/* enters with txlock held */
+static int
+tx(void)
+{
+ struct sk_buff *skb;
+
+ while ((skb = skb_dequeue(&skbtxq))) {
+ spin_unlock_irq(&txlock);
+ dev_queue_xmit(skb);
+ spin_lock_irq(&txlock);
+ }
+ return 0;
+}
+
int
is_aoe_netif(struct net_device *ifp)
{
@@ -88,10 +108,14 @@ void
aoenet_xmit(struct sk_buff_head *queue)
{
struct sk_buff *skb, *tmp;
+ ulong flags;

skb_queue_walk_safe(queue, skb, tmp) {
__skb_unlink(skb, queue);
- dev_queue_xmit(skb);
+ spin_lock_irqsave(&txlock, flags);
+ skb_queue_tail(&skbtxq, skb);
+ spin_unlock_irqrestore(&txlock, flags);
+ wake_up(&txwq);
}
}

@@ -169,6 +193,15 @@ static struct packet_type aoe_pt __read_mostly = {
int __init
aoenet_init(void)
{
+ skb_queue_head_init(&skbtxq);
+ init_waitqueue_head(&txwq);
+ spin_lock_init(&txlock);
+ kts.lock = &txlock;
+ kts.fn = tx;
+ kts.waitq = &txwq;
+ kts.name = "aoe_tx";
+ if (aoe_ktstart(&kts))
+ return -EAGAIN;
dev_add_pack(&aoe_pt);
return 0;
}
@@ -176,6 +209,8 @@ aoenet_init(void)
void
aoenet_exit(void)
{
+ aoe_ktstop(&kts);
+ skb_queue_purge(&skbtxq);
dev_remove_pack(&aoe_pt);
}

--
1.7.2.5

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