Re: [PATCH 7/8] bus: remove per bus scan mode

[Kevin Traynor <ktraynor@redhat.com>]

On 3/23/26 10:53 AM, David Marchand wrote:
> Following the refactoring of device selection, it becomes more apparent
> that there is no need for a per bus scan mode.
> -a / -b options are mutually exclusive.
> --vdev option works in parallel of allow/block list scan mode.
>

-a/-b are mutually exclusive but does it mean "-a 0000:01:00.0" stops
default probe for all devices on other buses ? Is it a change in behavior ?

(I could probably test but I guess you thought about this case given the
nature of patch.)

> Remove this (internal) notion.
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---
>  lib/eal/common/eal_common_bus.c     | 20 ++++++++++++++++++-
>  lib/eal/common/eal_common_devargs.c |  8 +++-----
>  lib/eal/common/eal_private.h        | 31 +++++++++++++++++++++++++++++
>  lib/eal/include/bus_driver.h        | 18 -----------------
>  4 files changed, 53 insertions(+), 24 deletions(-)
> 
> diff --git a/lib/eal/common/eal_common_bus.c b/lib/eal/common/eal_common_bus.c
> index 2ca0af7914..27a31bbefa 100644
> --- a/lib/eal/common/eal_common_bus.c
> +++ b/lib/eal/common/eal_common_bus.c
> @@ -18,6 +18,8 @@
>  static struct rte_bus_list rte_bus_list =
>  	TAILQ_HEAD_INITIALIZER(rte_bus_list);
>  
> +static enum rte_bus_scan_mode bus_scan_mode;
> +
>  RTE_EXPORT_SYMBOL(rte_bus_name)
>  const char *
>  rte_bus_name(const struct rte_bus *bus)
> @@ -252,7 +254,7 @@ rte_bus_is_ignored_device(const struct rte_bus *bus, const char *dev_name)
>  {
>  	struct rte_devargs *devargs = rte_bus_find_devargs(bus, dev_name);
>  
> -	switch (bus->conf.scan_mode) {
> +	switch (rte_bus_scan_mode_get()) {
>  	case RTE_BUS_SCAN_ALLOWLIST:
>  		if (devargs && devargs->policy == RTE_DEV_ALLOWED)
>  			return false;
> @@ -266,6 +268,22 @@ rte_bus_is_ignored_device(const struct rte_bus *bus, const char *dev_name)
>  	return true;
>  }
>  
> +enum rte_bus_scan_mode
> +rte_bus_scan_mode_get(void)
> +{
> +	return bus_scan_mode;
> +}
> +
> +int
> +rte_bus_scan_mode_set(enum rte_bus_scan_mode scan_mode)
> +{
> +	if (bus_scan_mode != RTE_BUS_SCAN_UNDEFINED)
> +		return -EINVAL;
> +
> +	bus_scan_mode = scan_mode;
> +	return 0;
> +}
> +
>  /*
>   * Get iommu class of devices on the bus.
>   */
> diff --git a/lib/eal/common/eal_common_devargs.c b/lib/eal/common/eal_common_devargs.c
> index c523429d67..8083bdebc2 100644
> --- a/lib/eal/common/eal_common_devargs.c
> +++ b/lib/eal/common/eal_common_devargs.c
> @@ -330,7 +330,6 @@ int
>  rte_devargs_add(enum rte_devtype devtype, const char *devargs_str)
>  {
>  	struct rte_devargs *devargs = NULL;
> -	struct rte_bus *bus = NULL;
>  	const char *dev = devargs_str;
>  
>  	/* use calloc instead of rte_zmalloc as it's called early at init */
> @@ -341,14 +340,13 @@ rte_devargs_add(enum rte_devtype devtype, const char *devargs_str)
>  	if (rte_devargs_parse(devargs, dev))
>  		goto fail;
>  	devargs->type = devtype;
> -	bus = devargs->bus;
>  	if (devargs->type == RTE_DEVTYPE_BLOCKED)
>  		devargs->policy = RTE_DEV_BLOCKED;
> -	if (bus->conf.scan_mode == RTE_BUS_SCAN_UNDEFINED) {
> +	if (rte_bus_scan_mode_get() == RTE_BUS_SCAN_UNDEFINED) {
>  		if (devargs->policy == RTE_DEV_ALLOWED)
> -			bus->conf.scan_mode = RTE_BUS_SCAN_ALLOWLIST;
> +			rte_bus_scan_mode_set(RTE_BUS_SCAN_ALLOWLIST);
>  		else if (devargs->policy == RTE_DEV_BLOCKED)
> -			bus->conf.scan_mode = RTE_BUS_SCAN_BLOCKLIST;
> +			rte_bus_scan_mode_set(RTE_BUS_SCAN_BLOCKLIST);
>  	}
>  	TAILQ_INSERT_TAIL(&devargs_list, devargs, next);
>  	return 0;
> diff --git a/lib/eal/common/eal_private.h b/lib/eal/common/eal_private.h
> index e032dd10c9..12db04dce2 100644
> --- a/lib/eal/common/eal_private.h
> +++ b/lib/eal/common/eal_private.h
> @@ -469,6 +469,37 @@ int rte_eal_memory_detach(void);
>   */
>  struct rte_bus *rte_bus_find_by_device_name(const char *str);
>  
> +/**
> + * Bus scan policies
> + */
> +enum rte_bus_scan_mode {
> +	RTE_BUS_SCAN_UNDEFINED,
> +	RTE_BUS_SCAN_ALLOWLIST,
> +	RTE_BUS_SCAN_BLOCKLIST,
> +};
> +
> +/**
> + * Retrieve the current bus scanning mode.
> + *
> + * @return
> + *   The current bus scanning mode.
> + */
> +enum rte_bus_scan_mode rte_bus_scan_mode_get(void);
> +
> +/**
> + * Change the bus scanning mode.
> + * Changing the mode can only be done once from undefined to allow list or to block list.
> + * No change from allow to block (or vice versa) is allowed.
> + *
> + * @param scan_mode
> + *   The scanning mode to apply.
> + *
> + * @return
> + *   0 on successful change.
> + *   < 0 on failure.
> + */
> +int rte_bus_scan_mode_set(enum rte_bus_scan_mode scan_mode);
> +
>  /**
>   * For each device on the buses, call the driver-specific function for
>   * device cleanup.
> diff --git a/lib/eal/include/bus_driver.h b/lib/eal/include/bus_driver.h
> index e67e052404..9045d64816 100644
> --- a/lib/eal/include/bus_driver.h
> +++ b/lib/eal/include/bus_driver.h
> @@ -232,23 +232,6 @@ typedef int (*rte_bus_sigbus_handler_t)(const void *failure_addr);
>   */
>  typedef int (*rte_bus_cleanup_t)(void);
>  
> -/**
> - * Bus scan policies
> - */
> -enum rte_bus_scan_mode {
> -	RTE_BUS_SCAN_UNDEFINED,
> -	RTE_BUS_SCAN_ALLOWLIST,
> -	RTE_BUS_SCAN_BLOCKLIST,
> -};
> -
> -/**
> - * A structure used to configure bus operations.
> - */
> -struct rte_bus_conf {
> -	enum rte_bus_scan_mode scan_mode; /**< Scan policy. */
> -};
> -
> -
>  /**
>   * Get common iommu class of the all the devices on the bus. The bus may
>   * check that those devices are attached to iommu driver.
> @@ -277,7 +260,6 @@ struct rte_bus {
>  	rte_bus_devargs_parse_t devargs_parse; /**< Parse bus devargs */
>  	rte_dev_dma_map_t dma_map;   /**< DMA map for device in the bus */
>  	rte_dev_dma_unmap_t dma_unmap; /**< DMA unmap for device in the bus */
> -	struct rte_bus_conf conf;    /**< Bus configuration */
>  	rte_bus_get_iommu_class_t get_iommu_class; /**< Get iommu class */
>  	rte_dev_iterate_t dev_iterate; /**< Device iterator. */
>  	rte_bus_hot_unplug_handler_t hot_unplug_handler;