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Date: Thu, 3 Dec 2009 21:29:38 +0100
From: Jarek Poplawski <jarkao2@...il.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: David Miller <davem@...emloft.net>, mchan@...adcom.com,
kaber@...sh.net, netdev@...r.kernel.org
Subject: [PATCH v4] net: Introduce realloc_netdev_mq()
On Thu, Dec 03, 2009 at 06:05:39PM +0100, Eric Dumazet wrote:
> Jarek Poplawski a écrit :
> > On Thu, Dec 03, 2009 at 05:36:40PM +0100, Jarek Poplawski wrote:
> >> On Thu, Dec 03, 2009 at 04:17:43PM +0100, Eric Dumazet wrote:
> >>> if (realloc_netdev_mq(dev, real_queues))
> >>> dev->real_num_tx_queues = real_queues;
> >>>
> >>> In this case the memory error is not fatal.
> >> Good point! We can consider doing this inside the function too?
> >
> > Hmm... Of course, not exactly this - I mean using min().
>
> Sure, allowing to reduce the count in case new allocation failed.
>
> And report an error if caller wanted to increase number of queues and allocation failed.
Hmm... After re-thinking it looks a bit too complex to me. I think,
there is no reason to not report this error since in most cases it
shouldn't be fatal. That's why I skipped this check in the changelog
example. Unless I miss something?
Thanks,
Jarek P.
---------------> (take 4)
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)
...
}
Alternatively, it can be done in reverse order: starting from the
highest queue_count and reallocating with a lower one.
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>
Cc: Eric Dumazet <eric.dumazet@...il.com>
---
include/linux/netdevice.h | 1 +
net/core/dev.c | 69 ++++++++++++++++++++++++++++++++------------
2 files changed, 51 insertions(+), 19 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index daf13d3..36cbd53 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1904,6 +1904,7 @@ extern void ether_setup(struct net_device *dev);
extern struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
void (*setup)(struct net_device *),
unsigned int queue_count);
+extern int realloc_netdev_mq(struct net_device *dev, unsigned int queue_count);
#define alloc_netdev(sizeof_priv, name, setup) \
alloc_netdev_mq(sizeof_priv, name, setup, 1)
extern int register_netdev(struct net_device *dev);
diff --git a/net/core/dev.c b/net/core/dev.c
index e3e18de..1f45bae 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5265,11 +5265,53 @@ 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, but dev->real_num_tx_queue is
+ * replaced if the queue_count is lower.
+ */
+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 (re)allocate "
+ "tx qdiscs.\n");
+ if (dev->real_num_tx_queues > queue_count)
+ dev->real_num_tx_queues = queue_count;
+
+ 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 +5322,12 @@ 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 +5349,12 @@ 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 +5362,8 @@ 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 +5373,7 @@ 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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