Re: [dpdk-dev] [PATCH v4 1/5] eal: add API for bus close

[David Marchand <david.marchand@redhat.com>]

On Thu, Oct 8, 2020 at 5:31 PM <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>
> ---
>  lib/librte_eal/common/eal_common_bus.c | 32 +++++++++++++++++++++++++-
>  lib/librte_eal/include/rte_bus.h       | 27 +++++++++++++++++++++-
>  lib/librte_eal/linux/eal.c             |  1 +
>  lib/librte_eal/rte_eal_version.map     |  1 +
>  4 files changed, 59 insertions(+), 2 deletions(-)

This is a new EAL API, please update the release notes.


>
> 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;
> +               }
> +
> +               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;

We should propagate that an error occurred so that the caller is aware
something went wrong.


> +}
> +
>  /* 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..7bf7e81b2 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 +67,20 @@ typedef int (*rte_bus_scan_t)(void);
>   */
>  typedef int (*rte_bus_probe_t)(void);
>
> +/**
> + * Implementation specific close function which is responsible for resetting all
> + * detected devices on the bus to a default state, closing UIO nodes or VFIO
> + * groups and also freeing any memory allocated during rte_bus_probe like
> + * private resources for device list.
> + *
> + * 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);
> +
>  /**
>   * Device iterator to find a device on a bus.
>   *
> @@ -248,6 +262,7 @@ struct rte_bus {
>         const char *name;            /**< Name of the bus */
>         rte_bus_scan_t scan;         /**< Scan for devices attached to bus */
>         rte_bus_probe_t probe;       /**< Probe devices on bus */
> +       rte_bus_close_t close;       /**< Close devices on bus */
>         rte_bus_find_device_t find_device; /**< Find a device on the bus */
>         rte_bus_plug_t plug;         /**< Probe single device for drivers */
>         rte_bus_unplug_t unplug;     /**< Remove single device from driver */
> @@ -301,6 +316,16 @@ int rte_bus_scan(void);
>   */
>  int rte_bus_probe(void);
>
> +/**

Missing a banner:

+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice

> + * For each device on the buses, call the device specific close.
> + *
> + * @return
> + *      0 for successful close
> + *     !0 otherwise
> + */
> +__rte_experimental
> +int rte_bus_close(void);
> +
>  /**
>   * Dump information of all the buses registered with EAL.
>   *
> diff --git a/lib/librte_eal/linux/eal.c b/lib/librte_eal/linux/eal.c
> index 9cf0e2ec0..1e1256f07 100644
> --- a/lib/librte_eal/linux/eal.c
> +++ b/lib/librte_eal/linux/eal.c
> @@ -1358,6 +1358,7 @@ rte_eal_cleanup(void)
>
>         if (rte_eal_process_type() == RTE_PROC_PRIMARY)
>                 rte_memseg_walk(mark_freeable, NULL);
> +       rte_bus_close();
>         rte_service_finalize();
>         rte_mp_channel_cleanup();
>         rte_trace_save();

You can squash patch 4 and patch 5 in this patch so that we update all
OS-specific bits at once.


> diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
> index a93dea9fe..8e226b297 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -400,6 +400,7 @@ EXPERIMENTAL {
>         # added in 20.11
>         __rte_eal_trace_generic_size_t;
>         rte_service_lcore_may_be_active;
> +       rte_bus_close;

Please, alphabetical order.


>  };
>
>  INTERNAL {
> --
> 2.17.1
>


-- 
David Marchand