From: Alan Ott <alan@signal11.us>
To: David Hauweele <david@hauweele.net>
Cc: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>,
Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>,
linux-zigbee-devel@lists.sourceforge.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [Linux-zigbee-devel] [PATCH 1/2] mrf24j40: Avoid transmission while receiving a frame
Date: Mon, 13 May 2013 23:22:12 -0400 [thread overview]
Message-ID: <5191ADE4.8040709@signal11.us> (raw)
In-Reply-To: <1368112788-25701-1-git-send-email-david@hauweele.net>
On 5/9/13 11:19 AM, David Hauweele wrote:
> The transceiver may fail under heavy traffic when a frame is transmitted
> while receiving another frame.
>
> This patch uses a mutex to separate the transmission and reception of
> frames along with a secondary working queue to avoid a deadlock while
> waiting for the transmission interrupt.
>
Have you observed this failure? I have put this kind of thing in before
(several times actually) but ultimately convinced myself each time that
it was not necessary. I'm happy to be shown wrong.
> Signed-off-by: David Hauweele <david@hauweele.net>
> ---
> drivers/net/ieee802154/mrf24j40.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ieee802154/mrf24j40.c b/drivers/net/ieee802154/mrf24j40.c
> index ede3ce4..1e3ddf3 100644
> --- a/drivers/net/ieee802154/mrf24j40.c
> +++ b/drivers/net/ieee802154/mrf24j40.c
> @@ -82,8 +82,10 @@ struct mrf24j40 {
> struct ieee802154_dev *dev;
>
> struct mutex buffer_mutex; /* only used to protect buf */
> + struct mutex txrx_mutex; /* avoid transmission while receiving a frame */
> struct completion tx_complete;
> struct work_struct irqwork;
> + struct work_struct rxwork;
> u8 *buf; /* 3 bytes. Used for SPI single-register transfers. */
> };
>
> @@ -353,6 +355,8 @@ static int mrf24j40_tx(struct ieee802154_dev *dev, struct sk_buff *skb)
> /* Set TXNACKREQ if the ACK bit is set in the packet. */
> if (skb->data[0] & IEEE802154_FC_ACK_REQ)
> val |= 0x4;
> +
> + mutex_lock(&devrec->txrx_mutex);
> write_short_reg(devrec, REG_TXNCON, val);
>
> INIT_COMPLETION(devrec->tx_complete);
> @@ -361,6 +365,9 @@ static int mrf24j40_tx(struct ieee802154_dev *dev, struct sk_buff *skb)
> ret = wait_for_completion_interruptible_timeout(
> &devrec->tx_complete,
> 5 * HZ);
> +
> + mutex_unlock(&devrec->txrx_mutex);
> +
> if (ret == -ERESTARTSYS)
> goto err;
> if (ret == 0) {
> @@ -535,6 +542,8 @@ static int mrf24j40_handle_rx(struct mrf24j40 *devrec)
> int ret = 0;
> struct sk_buff *skb;
>
> + mutex_lock(&devrec->txrx_mutex);
> +
> /* Turn off reception of packets off the air. This prevents the
> * device from overwriting the buffer while we're reading it. */
> ret = read_short_reg(devrec, REG_BBREG1, &val);
> @@ -575,6 +584,8 @@ out:
> val &= ~0x4; /* Clear RXDECINV */
> write_short_reg(devrec, REG_BBREG1, val);
>
> + mutex_unlock(&devrec->txrx_mutex);
> +
> return ret;
> }
>
> @@ -616,12 +627,19 @@ static void mrf24j40_isrwork(struct work_struct *work)
>
> /* Check for Rx */
> if (intstat & 0x8)
> - mrf24j40_handle_rx(devrec);
> + schedule_work(&devrec->rxwork);
>
mrf24f40_isrwork() is already called from a workqueue.
> out:
> enable_irq(devrec->spi->irq);
> }
>
> +static void mrf24j40_rxwork(struct work_struct *work)
> +{
> + struct mrf24j40 *devrec = container_of(work, struct mrf24j40, rxwork);
> +
> + mrf24j40_handle_rx(devrec);
> +}
> +
> static int mrf24j40_probe(struct spi_device *spi)
> {
> int ret = -ENOMEM;
> @@ -648,8 +666,10 @@ static int mrf24j40_probe(struct spi_device *spi)
> spi->max_speed_hz = MAX_SPI_SPEED_HZ;
>
> mutex_init(&devrec->buffer_mutex);
> + mutex_init(&devrec->txrx_mutex);
> init_completion(&devrec->tx_complete);
> INIT_WORK(&devrec->irqwork, mrf24j40_isrwork);
> + INIT_WORK(&devrec->rxwork, mrf24j40_rxwork);
> devrec->spi = spi;
> spi_set_drvdata(spi, devrec);
>
>
next prev parent reply other threads:[~2013-05-14 3:22 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-09 15:19 [PATCH 1/2] mrf24j40: Avoid transmission while receiving a frame David Hauweele
2013-05-09 15:19 ` [PATCH 2/2] mrf24j40: Keep the interrupt line enabled David Hauweele
[not found] ` <1368112788-25701-2-git-send-email-david-1EggE+PRa6vk1uMJSBkQmQ@public.gmane.org>
2013-05-14 3:55 ` Alan Ott
2013-05-16 21:34 ` [Linux-zigbee-devel] " David Hauweele
2013-05-19 23:04 ` Alan Ott
2013-05-21 16:17 ` David Hauweele
[not found] ` <CAO+c-UXymPjYysvh2kM36gcOsL3P51YWq+aYhEqX8oCySwBcaQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-21 18:22 ` Alan Ott
2013-05-14 3:22 ` Alan Ott [this message]
[not found] ` <5191ADE4.8040709-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
2013-05-16 17:45 ` [PATCH 1/2] mrf24j40: Avoid transmission while receiving a frame David Hauweele
[not found] ` <CAO+c-UVJQJbmmmCS4hxAEYHKa8gEU1Bs=y+Rv_A75UHeBZxc+w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-20 0:05 ` [PATCH testing] mrf24j40: Move INIT_COMPLETION to before the packet is sent Alan Ott
2013-05-22 2:01 ` [PATCH beta 1] 0/3] Fix race conditions in mrf24j40 interrupts Alan Ott
[not found] ` <1369188080-8904-1-git-send-email-alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
2013-05-22 2:01 ` [PATCH beta 1] 1/3] mrf24j40: Move INIT_COMPLETION() to before packet transmission Alan Ott
2013-05-22 2:01 ` [PATCH beta 1] 2/3] mrf24j40: Use threaded IRQ handler Alan Ott
2013-10-06 3:52 ` [PATCH v1 0/3] Fix race conditions in mrf24j40 interrupts Alan Ott
[not found] ` <1381031544-2960-1-git-send-email-alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
2013-10-06 3:52 ` [PATCH v1 1/3] mrf24j40: Move INIT_COMPLETION() to before packet transmission Alan Ott
2013-10-06 3:52 ` [PATCH v1 2/3] mrf24j40: Use threaded IRQ handler Alan Ott
2013-10-06 3:52 ` [PATCH v1 3/3] mrf24j40: Use level-triggered interrupts Alan Ott
2013-10-08 19:32 ` [PATCH v1 0/3] Fix race conditions in mrf24j40 interrupts David Miller
2013-05-22 2:01 ` [PATCH beta 1] 3/3] mrf24j40: Use level-triggered interrupts Alan Ott
2013-05-22 2:03 ` [PATCH beta 1] 0/3] Fix race conditions in mrf24j40 interrupts Alan Ott
2013-05-22 20:32 ` David Hauweele
[not found] ` <CAO+c-UV1bZZEE=9=7VVn3f1eLWzCpYCK9eZnnvzNwcPOKKtKLA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-23 6:36 ` Alan Ott
[not found] ` <519DB8E6.4020709-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
2013-05-23 17:54 ` David Hauweele
2013-05-23 19:33 ` Alan Ott
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