[PATCH v2 11/20] rpmsg: glink: Fix idr_lock from mutex to spinlock

[aneela@codeaurora.org (Arun Kumar Neelakantam)]

On 8/24/2017 12:51 PM, Sricharan R wrote:
> The channel members lcids, rcids synchronised using
> the idr_lock is accessed in both atomic/non-atomic
> contexts. The readers are not currently synchronised.
> That no correct, so add the readers as well under the
> lock and use a spinlock.
>
> Signed-off-by: Sricharan R <sricharan@codeaurora.org>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>

Regards,
Arun N
> ---
>   drivers/rpmsg/qcom_glink_native.c | 58 +++++++++++++++++++++++++++------------
>   1 file changed, 40 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 777ac6b..588a56c 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -92,7 +92,7 @@ struct qcom_glink {
>   
>   	struct mutex tx_lock;
>   
> -	struct mutex idr_lock;
> +	spinlock_t idr_lock;
>   	struct idr lcids;
>   	struct idr rcids;
>   	unsigned long features;
> @@ -309,14 +309,15 @@ static int qcom_glink_send_open_req(struct qcom_glink *glink,
>   	int name_len = strlen(channel->name) + 1;
>   	int req_len = ALIGN(sizeof(req.msg) + name_len, 8);
>   	int ret;
> +	unsigned long flags;
>   
>   	kref_get(&channel->refcount);
>   
> -	mutex_lock(&glink->idr_lock);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	ret = idr_alloc_cyclic(&glink->lcids, channel,
>   			       RPM_GLINK_CID_MIN, RPM_GLINK_CID_MAX,
>   			       GFP_KERNEL);
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   	if (ret < 0)
>   		return ret;
>   
> @@ -334,10 +335,10 @@ static int qcom_glink_send_open_req(struct qcom_glink *glink,
>   	return 0;
>   
>   remove_idr:
> -	mutex_lock(&glink->idr_lock);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	idr_remove(&glink->lcids, channel->lcid);
>   	channel->lcid = 0;
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   	return ret;
>   }
> @@ -463,6 +464,7 @@ static int qcom_glink_rx_data(struct qcom_glink *glink, size_t avail)
>   	unsigned int chunk_size;
>   	unsigned int left_size;
>   	unsigned int rcid;
> +	unsigned long flags;
>   
>   	if (avail < sizeof(hdr)) {
>   		dev_dbg(glink->dev, "Not enough data in fifo\n");
> @@ -482,7 +484,9 @@ static int qcom_glink_rx_data(struct qcom_glink *glink, size_t avail)
>   		return -EINVAL;
>   
>   	rcid = le16_to_cpu(hdr.msg.param1);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	channel = idr_find(&glink->rcids, rcid);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   	if (!channel) {
>   		dev_dbg(glink->dev, "Data on non-existing channel\n");
>   
> @@ -543,11 +547,13 @@ static int qcom_glink_rx_open_ack(struct qcom_glink *glink, unsigned int lcid)
>   {
>   	struct glink_channel *channel;
>   
> +	spin_lock(&glink->idr_lock);
>   	channel = idr_find(&glink->lcids, lcid);
>   	if (!channel) {
>   		dev_err(glink->dev, "Invalid open ack packet\n");
>   		return -EINVAL;
>   	}
> +	spin_unlock(&glink->idr_lock);
>   
>   	complete(&channel->open_ack);
>   
> @@ -621,6 +627,7 @@ static struct glink_channel *qcom_glink_create_local(struct qcom_glink *glink,
>   {
>   	struct glink_channel *channel;
>   	int ret;
> +	unsigned long flags;
>   
>   	channel = qcom_glink_alloc_channel(glink, name);
>   	if (IS_ERR(channel))
> @@ -644,9 +651,9 @@ static struct glink_channel *qcom_glink_create_local(struct qcom_glink *glink,
>   
>   err_timeout:
>   	/* qcom_glink_send_open_req() did register the channel in lcids*/
> -	mutex_lock(&glink->idr_lock);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	idr_remove(&glink->lcids, channel->lcid);
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   release_channel:
>   	/* Release qcom_glink_send_open_req() reference */
> @@ -703,11 +710,14 @@ static struct rpmsg_endpoint *qcom_glink_create_ept(struct rpmsg_device *rpdev,
>   	const char *name = chinfo.name;
>   	int cid;
>   	int ret;
> +	unsigned long flags;
>   
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	idr_for_each_entry(&glink->rcids, channel, cid) {
>   		if (!strcmp(channel->name, name))
>   			break;
>   	}
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   	if (!channel) {
>   		channel = qcom_glink_create_local(glink, name);
> @@ -829,11 +839,14 @@ static int qcom_glink_rx_open(struct qcom_glink *glink, unsigned int rcid,
>   	struct device_node *node;
>   	int lcid;
>   	int ret;
> +	unsigned long flags;
>   
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	idr_for_each_entry(&glink->lcids, channel, lcid) {
>   		if (!strcmp(channel->name, name))
>   			break;
>   	}
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   	if (!channel) {
>   		channel = qcom_glink_alloc_channel(glink, name);
> @@ -844,15 +857,15 @@ static int qcom_glink_rx_open(struct qcom_glink *glink, unsigned int rcid,
>   		create_device = true;
>   	}
>   
> -	mutex_lock(&glink->idr_lock);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	ret = idr_alloc(&glink->rcids, channel, rcid, rcid + 1, GFP_KERNEL);
>   	if (ret < 0) {
>   		dev_err(glink->dev, "Unable to insert channel into rcid list\n");
> -		mutex_unlock(&glink->idr_lock);
> +		spin_unlock_irqrestore(&glink->idr_lock, flags);
>   		goto free_channel;
>   	}
>   	channel->rcid = ret;
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   	complete(&channel->open_req);
>   
> @@ -886,10 +899,10 @@ static int qcom_glink_rx_open(struct qcom_glink *glink, unsigned int rcid,
>   free_rpdev:
>   	kfree(rpdev);
>   rcid_remove:
> -	mutex_lock(&glink->idr_lock);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	idr_remove(&glink->rcids, channel->rcid);
>   	channel->rcid = 0;
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   free_channel:
>   	/* Release the reference, iff we took it */
>   	if (create_device)
> @@ -902,8 +915,11 @@ static void qcom_glink_rx_close(struct qcom_glink *glink, unsigned int rcid)
>   {
>   	struct rpmsg_channel_info chinfo;
>   	struct glink_channel *channel;
> +	unsigned long flags;
>   
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	channel = idr_find(&glink->rcids, rcid);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   	if (WARN(!channel, "close request on unknown channel\n"))
>   		return;
>   
> @@ -917,10 +933,10 @@ static void qcom_glink_rx_close(struct qcom_glink *glink, unsigned int rcid)
>   
>   	qcom_glink_send_close_ack(glink, channel->rcid);
>   
> -	mutex_lock(&glink->idr_lock);
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	idr_remove(&glink->rcids, channel->rcid);
>   	channel->rcid = 0;
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   	kref_put(&channel->refcount, qcom_glink_channel_release);
>   }
> @@ -928,15 +944,18 @@ static void qcom_glink_rx_close(struct qcom_glink *glink, unsigned int rcid)
>   static void qcom_glink_rx_close_ack(struct qcom_glink *glink, unsigned int lcid)
>   {
>   	struct glink_channel *channel;
> +	unsigned long flags;
>   
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	channel = idr_find(&glink->lcids, lcid);
> -	if (WARN(!channel, "close ack on unknown channel\n"))
> +	if (WARN(!channel, "close ack on unknown channel\n")) {
> +		spin_unlock_irqrestore(&glink->idr_lock, flags);
>   		return;
> +	}
>   
> -	mutex_lock(&glink->idr_lock);
>   	idr_remove(&glink->lcids, channel->lcid);
>   	channel->lcid = 0;
> -	mutex_unlock(&glink->idr_lock);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   
>   	kref_put(&channel->refcount, qcom_glink_channel_release);
>   }
> @@ -1017,7 +1036,7 @@ struct qcom_glink *qcom_glink_native_probe(struct device *dev,
>   	INIT_LIST_HEAD(&glink->rx_queue);
>   	INIT_WORK(&glink->rx_work, qcom_glink_work);
>   
> -	mutex_init(&glink->idr_lock);
> +	spin_lock_init(&glink->idr_lock);
>   	idr_init(&glink->lcids);
>   	idr_init(&glink->rcids);
>   
> @@ -1060,6 +1079,7 @@ void qcom_glink_native_remove(struct qcom_glink *glink)
>   	struct glink_channel *channel;
>   	int cid;
>   	int ret;
> +	unsigned long flags;
>   
>   	disable_irq(glink->irq);
>   	cancel_work_sync(&glink->rx_work);
> @@ -1068,12 +1088,14 @@ void qcom_glink_native_remove(struct qcom_glink *glink)
>   	if (ret)
>   		dev_warn(glink->dev, "Can't remove GLINK devices: %d\n", ret);
>   
> +	spin_lock_irqsave(&glink->idr_lock, flags);
>   	/* Release any defunct local channels, waiting for close-ack */
>   	idr_for_each_entry(&glink->lcids, channel, cid)
>   		kref_put(&channel->refcount, qcom_glink_channel_release);
>   
>   	idr_destroy(&glink->lcids);
>   	idr_destroy(&glink->rcids);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
>   	mbox_free_channel(glink->mbox_chan);
>   }
>