[dpdk-dev] [PATCH] bus/vdev: add custom scan hook

[Tan, Jianfeng]

On 12/1/2017 8:36 AM, Thomas Monjalon wrote:
> The scan callback allows to spawn a vdev automatically
> given some custom scan rules.
> It is especially useful to create a TAP device automatically
> connected to a netdevice as remote.
>
> Signed-off-by: Thomas Monjalon <thomas at monjalon.net>
> ---
> warning: to be tested
> ---
>   drivers/bus/vdev/rte_bus_vdev.h | 29 ++++++++++++++++
>   drivers/bus/vdev/vdev.c         | 75 +++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 104 insertions(+)
>
> diff --git a/drivers/bus/vdev/rte_bus_vdev.h b/drivers/bus/vdev/rte_bus_vdev.h
> index 41762b853..a90382f49 100644
> --- a/drivers/bus/vdev/rte_bus_vdev.h
> +++ b/drivers/bus/vdev/rte_bus_vdev.h
> @@ -124,6 +124,35 @@ RTE_PMD_EXPORT_NAME(nm, __COUNTER__)
>   #define RTE_PMD_REGISTER_ALIAS(nm, alias)\
>   static const char *vdrvinit_ ## nm ## _alias = RTE_STR(alias)
>   
> +typedef void (*rte_vdev_scan_callback)(void *user_arg);
> +
> +/**
> + * Add a callback to be called on vdev scan
> + * before reading the devargs list.
> + *
> + * @param callback
> + *   The function to be called which can update the devargs list.
> + * @param user_arg
> + *   An opaque pointer passed to callback.
> + * @return
> + *   0 on success, -ENOMEM otherwise
> + */
> +int
> +rte_vdev_add_custom_scan(rte_vdev_scan_callback callback, void *user_arg);
> +
> +/**
> + * Remove a registered scan callback.
> + *
> + * @param callback
> + *   The registered function to be removed.
> + * @param user_arg
> + *   The associated opaque pointer or (void*)-1 for any.
> + * @return
> + *   0 on success
> + */
> +int
> +rte_vdev_remove_custom_scan(rte_vdev_scan_callback callback, void *user_arg);
> +
>   /**
>    * Initialize a driver specified by name.
>    *
> diff --git a/drivers/bus/vdev/vdev.c b/drivers/bus/vdev/vdev.c
> index fd7736d63..902f1e128 100644
> --- a/drivers/bus/vdev/vdev.c
> +++ b/drivers/bus/vdev/vdev.c
> @@ -44,6 +44,8 @@
>   #include <rte_common.h>
>   #include <rte_devargs.h>
>   #include <rte_memory.h>
> +#include <rte_tailq.h>
> +#include <rte_spinlock.h>
>   #include <rte_errno.h>
>   
>   #include "rte_bus_vdev.h"
> @@ -62,6 +64,16 @@ static struct vdev_device_list vdev_device_list =
>   struct vdev_driver_list vdev_driver_list =
>   	TAILQ_HEAD_INITIALIZER(vdev_driver_list);
>   
> +struct vdev_custom_scan {
> +	TAILQ_ENTRY(vdev_custom_scan) next;
> +	rte_vdev_scan_callback callback;
> +	void *user_arg;
> +};
> +TAILQ_HEAD(vdev_custom_scans, vdev_custom_scan);
> +static struct vdev_custom_scans vdev_custom_scans =
> +	TAILQ_HEAD_INITIALIZER(vdev_custom_scans);
> +static rte_spinlock_t vdev_custom_scan_lock = RTE_SPINLOCK_INITIALIZER;
> +
>   /* register a driver */
>   void
>   rte_vdev_register(struct rte_vdev_driver *driver)
> @@ -76,6 +88,53 @@ rte_vdev_unregister(struct rte_vdev_driver *driver)
>   	TAILQ_REMOVE(&vdev_driver_list, driver, next);
>   }
>   
> +int
> +rte_vdev_add_custom_scan(rte_vdev_scan_callback callback, void *user_arg)
> +{
> +	struct vdev_custom_scan *custom_scan;
> +
> +	rte_spinlock_lock(&vdev_custom_scan_lock);
> +
> +	/* check if already registered */
> +	TAILQ_FOREACH(custom_scan, &vdev_custom_scans, next) {
> +		if (custom_scan->callback == callback &&
> +				custom_scan->user_arg == user_arg)
> +			break;
> +	}
> +
> +	if (custom_scan == NULL) {
> +		custom_scan = malloc(sizeof(struct vdev_custom_scan));
> +		if (custom_scan != NULL) {
> +			custom_scan->callback = callback;
> +			custom_scan->user_arg = user_arg;
> +			TAILQ_INSERT_TAIL(&vdev_custom_scans, custom_scan, next);
> +		}
> +	}
> +
> +	rte_spinlock_unlock(&vdev_custom_scan_lock);
> +
> +	return (custom_scan == NULL) ? -ENOMEM : 0;
> +}
> +
> +int
> +rte_vdev_remove_custom_scan(rte_vdev_scan_callback callback, void *user_arg)
> +{
> +	struct vdev_custom_scan *custom_scan, *tmp_scan;
> +
> +	rte_spinlock_lock(&vdev_custom_scan_lock);
> +	TAILQ_FOREACH_SAFE(custom_scan, &vdev_custom_scans, next, tmp_scan) {
> +		if (custom_scan->callback != callback ||
> +				(custom_scan->user_arg != (void *)-1 &&
> +				custom_scan->user_arg != user_arg))
> +			continue;
> +		TAILQ_REMOVE(&vdev_custom_scans, custom_scan, next);
> +		free(custom_scan);
> +	}
> +	rte_spinlock_unlock(&vdev_custom_scan_lock);
> +
> +	return 0;
> +}
> +
>   static int
>   vdev_parse(const char *name, void *addr)
>   {
> @@ -260,6 +319,22 @@ vdev_scan(void)
>   {
>   	struct rte_vdev_device *dev;
>   	struct rte_devargs *devargs;
> +	struct vdev_custom_scan *custom_scan;
> +
> +	/* call custom scan callbacks if any */
> +	rte_spinlock_lock(&vdev_custom_scan_lock);
> +	TAILQ_FOREACH(custom_scan, &vdev_custom_scans, next) {
> +		if (custom_scan->callback != NULL)
> +			/*
> +			 * the callback should update devargs list
> +			 * by calling rte_eal_devargs_insert() with
> +			 *     devargs.bus = rte_bus_find_by_name("vdev");
> +			 *     devargs.type = RTE_DEVTYPE_VIRTUAL;
> +			 *     devargs.policy = RTE_DEV_WHITELISTED;
> +			 */
> +			custom_scan->callback(custom_scan->user_arg);
> +	}
> +	rte_spinlock_unlock(&vdev_custom_scan_lock);

You mentioned that we want to call the hook in the scan(), but it's now 
in parse()?

Thanks,
Jianfeng

>   
>   	/* for virtual devices we scan the devargs_list populated via cmdline */
>   	TAILQ_FOREACH(devargs, &devargs_list, next) {