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Message-ID: <20150312105211.GA21639@linux>
Date: Thu, 12 Mar 2015 06:52:11 -0400
From: "Ahmed S. Darwish" <darwish.07@...il.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: Olivier Sobrie <olivier@...rie.be>,
Oliver Hartkopp <socketcan@...tkopp.net>,
Wolfgang Grandegger <wg@...ndegger.com>,
Andri Yngvason <andri.yngvason@...el.com>,
Linux-CAN <linux-can@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] can: kvaser_usb: Utilize all possible tx URBs
On Wed, Mar 11, 2015 at 10:53:28PM +0100, Marc Kleine-Budde wrote:
> On 03/11/2015 06:39 PM, Ahmed S. Darwish wrote:
> > From: Ahmed S. Darwish <ahmed.darwish@...eo.com>
> >
> > The driver currently limits the number of outstanding, not yet
> > ACKed, transfers to 16 URBs. Meanwhile, the Kvaser firmware
> > provides its actual max supported number of outstanding
> > transmissions in its reply to the CMD_GET_SOFTWARE_INFO message.
> >
> > One example is the UsbCan-II HS/LS device which reports support
> > of up to 48 tx URBs instead of just 16, increasing the driver
> > throughput by two-fold and reducing the possibility of -ENOBUFs.
> >
> > Dynamically set the max tx URBs value according to firmware
> > replies.
> >
> > Signed-off-by: Ahmed S. Darwish <ahmed.darwish@...eo.com>
> > ---
> > drivers/net/can/usb/kvaser_usb.c | 55 +++++++++++++++++++++++++++-------------
> > 1 file changed, 37 insertions(+), 18 deletions(-)
> >
> > changelog-v3: No changes
> >
> > diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
> > index e97a08c..30b4d47 100644
> > --- a/drivers/net/can/usb/kvaser_usb.c
> > +++ b/drivers/net/can/usb/kvaser_usb.c
> > @@ -25,7 +25,6 @@
> > #include <linux/can/dev.h>
> > #include <linux/can/error.h>
> >
> > -#define MAX_TX_URBS 16
> > #define MAX_RX_URBS 4
> > #define START_TIMEOUT 1000 /* msecs */
> > #define STOP_TIMEOUT 1000 /* msecs */
> > @@ -456,8 +455,13 @@ struct kvaser_usb {
> > struct usb_endpoint_descriptor *bulk_in, *bulk_out;
> > struct usb_anchor rx_submitted;
> >
> > + /* @max_tx_urbs: Firmware-reported maximum number of possible
> > + * outstanding transmissions on this specific Kvaser hardware. The
> > + * value is also used as a sentinel for marking free URB contexts.
> > + */
> > u32 fw_version;
> > unsigned int nchannels;
> > + unsigned int max_tx_urbs;
> > enum kvaser_usb_family family;
> >
> > bool rxinitdone;
> > @@ -470,7 +474,7 @@ struct kvaser_usb_net_priv {
> >
> > spinlock_t tx_contexts_lock;
> > int active_tx_contexts;
> > - struct kvaser_usb_tx_urb_context tx_contexts[MAX_TX_URBS];
> > + struct kvaser_usb_tx_urb_context *tx_contexts;
> >
> > struct usb_anchor tx_submitted;
> > struct completion start_comp, stop_comp;
> > @@ -657,9 +661,13 @@ static int kvaser_usb_get_software_info(struct kvaser_usb *dev)
> > switch (dev->family) {
> > case KVASER_LEAF:
> > dev->fw_version = le32_to_cpu(msg.u.leaf.softinfo.fw_version);
> > + dev->max_tx_urbs =
> > + le16_to_cpu(msg.u.leaf.softinfo.max_outstanding_tx);
> > break;
> > case KVASER_USBCAN:
> > dev->fw_version = le32_to_cpu(msg.u.usbcan.softinfo.fw_version);
> > + dev->max_tx_urbs =
> > + le16_to_cpu(msg.u.usbcan.softinfo.max_outstanding_tx);
> > break;
> > }
> >
> > @@ -715,7 +723,7 @@ static void kvaser_usb_tx_acknowledge(const struct kvaser_usb *dev,
> >
> > stats = &priv->netdev->stats;
> >
> > - context = &priv->tx_contexts[tid % MAX_TX_URBS];
> > + context = &priv->tx_contexts[tid % dev->max_tx_urbs];
> >
> > /* Sometimes the state change doesn't come after a bus-off event */
> > if (priv->can.restart_ms &&
> > @@ -744,7 +752,7 @@ static void kvaser_usb_tx_acknowledge(const struct kvaser_usb *dev,
> > spin_lock_irqsave(&priv->tx_contexts_lock, flags);
> >
> > can_get_echo_skb(priv->netdev, context->echo_index);
> > - context->echo_index = MAX_TX_URBS;
> > + context->echo_index = dev->max_tx_urbs;
> > --priv->active_tx_contexts;
> > netif_wake_queue(priv->netdev);
> >
> > @@ -1512,11 +1520,13 @@ error:
> >
> > static void kvaser_usb_reset_tx_urb_contexts(struct kvaser_usb_net_priv *priv)
> > {
> > - int i;
> > + int i, max_tx_urbs;
> > +
> > + max_tx_urbs = priv->dev->max_tx_urbs;
> >
> > priv->active_tx_contexts = 0;
> > - for (i = 0; i < MAX_TX_URBS; i++)
> > - priv->tx_contexts[i].echo_index = MAX_TX_URBS;
> > + for (i = 0; i < max_tx_urbs; i++)
> > + priv->tx_contexts[i].echo_index = max_tx_urbs;
> > }
> >
> > /* This method might sleep. Do not call it in the atomic context
> > @@ -1702,14 +1712,14 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
> > *msg_tx_can_flags |= MSG_FLAG_REMOTE_FRAME;
> >
> > spin_lock_irqsave(&priv->tx_contexts_lock, flags);
> > - for (i = 0; i < ARRAY_SIZE(priv->tx_contexts); i++) {
> > - if (priv->tx_contexts[i].echo_index == MAX_TX_URBS) {
> > + for (i = 0; i < dev->max_tx_urbs; i++) {
> > + if (priv->tx_contexts[i].echo_index == dev->max_tx_urbs) {
> > context = &priv->tx_contexts[i];
> >
> > context->echo_index = i;
> > can_put_echo_skb(skb, netdev, context->echo_index);
> > ++priv->active_tx_contexts;
> > - if (priv->active_tx_contexts >= MAX_TX_URBS)
> > + if (priv->active_tx_contexts >= dev->max_tx_urbs)
> > netif_stop_queue(netdev);
> >
> > break;
> > @@ -1743,7 +1753,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
> > spin_lock_irqsave(&priv->tx_contexts_lock, flags);
> >
> > can_free_echo_skb(netdev, context->echo_index);
> > - context->echo_index = MAX_TX_URBS;
> > + context->echo_index = dev->max_tx_urbs;
> > --priv->active_tx_contexts;
> > netif_wake_queue(netdev);
> >
> > @@ -1881,7 +1891,7 @@ static int kvaser_usb_init_one(struct usb_interface *intf,
> > if (err)
> > return err;
> >
> > - netdev = alloc_candev(sizeof(*priv), MAX_TX_URBS);
> > + netdev = alloc_candev(sizeof(*priv), dev->max_tx_urbs);
> > if (!netdev) {
> > dev_err(&intf->dev, "Cannot alloc candev\n");
> > return -ENOMEM;
> > @@ -1889,6 +1899,13 @@ static int kvaser_usb_init_one(struct usb_interface *intf,
> >
> > priv = netdev_priv(netdev);
> >
> > + priv->tx_contexts = kzalloc(dev->max_tx_urbs *
> > + sizeof(*priv->tx_contexts), GFP_KERNEL);
> > + if (!priv->tx_contexts) {
> > + free_candev(netdev);
> > + return -ENOMEM;
> > + }
>
> I'm missing a free for the priv->tx_contexts. I see two options:
>
Correct. Should not have missed that.
> 1) use devm_kzalloc(), or
> 2) move struct kvaser_usb_tx_urb_context tx_contexts[]; to the end of
> struct kvaser_usb_net_priv, see [1] for an example.
>
> Without further testing, I think the correct alloc for that case
> would be:
> alloc_candev(sizeof(*priv + dev->max_tx_urbs *
> sizeof(struct kvaser_usb_tx_urb_context))
>
The first option looks better I guess. I'll have to check though
if the resource handling done by devm_kmalloc() will work even
if the probe() method fails with -ENODEV and the like...
> Marc
>
> [1] http://stackoverflow.com/questions/2060974/dynamic-array-in-struct-c
>
Thanks for the link. Didn't know that such a "hack" has gained
official status by C99 :-)
Regards,
Darwish
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