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Message-ID: <20091203141011.GA19986@ff.dom.local>
Date: Thu, 3 Dec 2009 14:10:11 +0000
From: Jarek Poplawski <jarkao2@...il.com>
To: David Miller <davem@...emloft.net>
Cc: mchan@...adcom.com, kaber@...sh.net, eric.dumazet@...il.com,
netdev@...r.kernel.org
Subject: [PATCH] net: Introduce realloc_netdev_mq()
On Mon, Nov 02, 2009 at 04:39:07AM -0800, David Miller wrote:
> From: Jarek Poplawski <jarkao2@...il.com>
> Date: Mon, 2 Nov 2009 12:30:29 +0000
>
> > Right, but it's not a 50% chance, I guess? A user most of the time
> > gets consistently multiqueue or non-multiqueue behavior after open,
> > unless I miss something. Then such an exceptional state could be
> > handled by real_num_tx_queues (just like in case of powered of cpus).
> > The main difference is to hold in num_tx_queues something that is
> > really available vs max possible value for all configs.
>
> I see your point, yes this would seem to be a reasonable way
> to start handling num_tx_queues and real_num_tx_queues.
Here is a proposal of netdev api change. I hope Michael finds time
to try if this can be really useful for drivers.
Thanks,
Jarek P.
--------------->
This patch separates allocation of TX subqueues from alloc_netdev_mq()
to realloc_netdev_mq() to allow for resizing like in this example:
some_nic_probe()
{
...
dev = alloc_etherdev_mq(sizeof(*bp), 1)
...
if (MSI-X_available && device_supports_MSI-X_and_multiqueue)
realloc_netdev_mq(dev, TX_MAX_RINGS)
register_netdev(dev)
...
}
The main difference is to hold in num_tx_queues something that is
really available, instead of max possible value for all configs, in
case of drivers allocating net_device at the beginning of the probe.
The description of alloc_netdev_mq() is fixed btw.
Reported-by: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: Jarek Poplawski <jarkao2@...il.com>
---
net/core/dev.c | 65 +++++++++++++++++++++++++++++++++++++++----------------
1 files changed, 46 insertions(+), 19 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index e3e18de..7ea3a77 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5265,11 +5265,49 @@ static void netdev_init_one_queue(struct net_device *dev,
queue->dev = dev;
}
-static void netdev_init_queues(struct net_device *dev)
+/**
+ * realloc_netdev_mq - (re)allocate network subqueues
+ * @dev: device
+ * @queue_count: the number of subqueues to (re)allocate
+ *
+ * (Re)allocates and initializes subqueue structs for each queue.
+ * It is allowed to use only until register_netdev().
+ * On error previous structs are intact.
+ */
+int realloc_netdev_mq(struct net_device *dev, unsigned int queue_count)
{
- netdev_init_one_queue(dev, &dev->rx_queue, NULL);
+ struct netdev_queue *tx;
+
+ tx = kcalloc(queue_count, sizeof(struct netdev_queue), GFP_KERNEL);
+ if (!tx) {
+ printk(KERN_ERR "alloc_netdev: Unable to allocate "
+ "tx qdiscs.\n");
+ return -ENOMEM;
+ }
+
+ kfree(dev->_tx);
+
+ dev->_tx = tx;
+ dev->num_tx_queues = queue_count;
+ dev->real_num_tx_queues = queue_count;
+
netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
+
+ return 0;
+}
+EXPORT_SYMBOL(realloc_netdev_mq);
+
+static int netdev_init_queues(struct net_device *dev, unsigned int queue_count)
+{
+ int err = realloc_netdev_mq(dev, queue_count);
+
+ if (err)
+ return err;
+
+ netdev_init_one_queue(dev, &dev->rx_queue, NULL);
spin_lock_init(&dev->tx_global_lock);
+
+ return 0;
}
/**
@@ -5280,13 +5318,12 @@ static void netdev_init_queues(struct net_device *dev)
* @queue_count: the number of subqueues to allocate
*
* Allocates a struct net_device with private data area for driver use
- * and performs basic initialization. Also allocates subquue structs
- * for each queue on the device at the end of the netdevice.
+ * and performs basic initialization. Also allocates subqueue structs
+ * for each queue on the device.
*/
struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
void (*setup)(struct net_device *), unsigned int queue_count)
{
- struct netdev_queue *tx;
struct net_device *dev;
size_t alloc_size;
struct net_device *p;
@@ -5308,16 +5345,12 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
return NULL;
}
- tx = kcalloc(queue_count, sizeof(struct netdev_queue), GFP_KERNEL);
- if (!tx) {
- printk(KERN_ERR "alloc_netdev: Unable to allocate "
- "tx qdiscs.\n");
- goto free_p;
- }
-
dev = PTR_ALIGN(p, NETDEV_ALIGN);
dev->padded = (char *)dev - (char *)p;
+ if (netdev_init_queues(dev, queue_count))
+ goto free_p;
+
if (dev_addr_init(dev))
goto free_tx;
@@ -5325,14 +5358,8 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
dev_net_set(dev, &init_net);
- dev->_tx = tx;
- dev->num_tx_queues = queue_count;
- dev->real_num_tx_queues = queue_count;
-
dev->gso_max_size = GSO_MAX_SIZE;
- netdev_init_queues(dev);
-
INIT_LIST_HEAD(&dev->napi_list);
INIT_LIST_HEAD(&dev->unreg_list);
INIT_LIST_HEAD(&dev->link_watch_list);
@@ -5342,7 +5369,7 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
return dev;
free_tx:
- kfree(tx);
+ kfree(dev->_tx);
free_p:
kfree(p);
--
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