Re: [dpdk-dev] [PATCH v3 1/3] eal: add API for bus close

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 8/26/2020 6:52 AM, rohit.raj@nxp.com wrote:
> From: Rohit Raj <rohit.raj@nxp.com>
> 
> As per the current code we have API for bus probe, but the
> bus close API is missing. This breaks the multi process
> scenarios as objects are not cleaned while terminating the
> secondary processes.
> 
> This patch adds a new API rte_bus_close() for cleanup of
> bus objects which were acquired during probe.
> 
> Signed-off-by: Rohit Raj <rohit.raj@nxp.com>
> ---
> 
> v3:
> * nit: combined nested if statements
> 
> v2:
> * Moved rte_bus_close call to rte_eal_cleanup path.
> 
>   lib/librte_eal/common/eal_common_bus.c | 32 +++++++++++++++++++++++++-
>   lib/librte_eal/include/rte_bus.h       | 25 +++++++++++++++++++-
>   lib/librte_eal/linux/eal.c             |  1 +
>   lib/librte_eal/rte_eal_version.map     |  3 +++
>   4 files changed, 59 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
> index baa5b532a..5fd7cf6c5 100644
> --- a/lib/librte_eal/common/eal_common_bus.c
> +++ b/lib/librte_eal/common/eal_common_bus.c
> @@ -1,5 +1,5 @@
>   /* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright 2016 NXP
> + * Copyright 2016,2020 NXP
>    */
>   
>   #include <stdio.h>
> @@ -56,6 +56,36 @@ rte_bus_scan(void)
>   	return 0;
>   }
>   
> +int
> +rte_bus_close(void)
> +{
> +	int ret;
> +	struct rte_bus *bus, *vbus = NULL;
> +
> +	TAILQ_FOREACH(bus, &rte_bus_list, next) {
> +		if (!strcmp(bus->name, "vdev")) {
> +			vbus = bus;
> +			continue;
> +		}

This special treatment for 'vdev' bus is done in probe to be sure physically 
device port ids start from '0',  I guess we don't need to do this for 'close'.

> +
> +		if (bus->close) {
> +			ret = bus->close();
> +			if (ret)
> +				RTE_LOG(ERR, EAL, "Bus (%s) close failed.\n",
> +					bus->name);
> +		}
> +	}
> +
> +	if (vbus && vbus->close) {
> +		ret = vbus->close();
> +		if (ret)
> +			RTE_LOG(ERR, EAL, "Bus (%s) close failed.\n",
> +				vbus->name);
> +	}
> +
> +	return 0;
> +}
> +
>   /* Probe all devices of all buses */
>   int
>   rte_bus_probe(void)
> diff --git a/lib/librte_eal/include/rte_bus.h b/lib/librte_eal/include/rte_bus.h
> index d3034d0ed..af4787b18 100644
> --- a/lib/librte_eal/include/rte_bus.h
> +++ b/lib/librte_eal/include/rte_bus.h
> @@ -1,5 +1,5 @@
>   /* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright 2016 NXP
> + * Copyright 2016,2020 NXP
>    */
>   
>   #ifndef _RTE_BUS_H_
> @@ -67,6 +67,18 @@ typedef int (*rte_bus_scan_t)(void);
>    */
>   typedef int (*rte_bus_probe_t)(void);
>   
> +/**
> + * Implementation specific close function which is responsible for closing
> + * devices on that bus.
> + *
> + * This is called while iterating over each registered bus.
> + *
> + * @return
> + *	0 for successful close
> + *	!0 for any error while closing
> + */
> +typedef int (*rte_bus_close_t)(void);
> +

As I checked the 'rte_fslmc_bus->close()' ops, it iterates on all devices in the 
bus instead of doing a bus level close, in that case
instead of adding a new 'close' bus operations, will it work if existing 
'bus->unplug(dev)' used?
Whatever done in the 'rte_fslmc_bus->close()' per device, can it be done under 
the 'fslmc_bus_unplug()'?

And in that case a 'rte_bus_remove()' API can be added which can call 
'bus->unplug(dev)' for all buses and it will be beneficial for all buses, and it 
can fit well into the 'rte_eal_cleanup()'.

What do you think?