Re: [PATCH v4] eal: add bus cleanup to eal cleanup

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, May 24, 2022 at 10:25:01AM +0100, Kevin Laatz wrote:
> During EAL init, all buses are probed and the devices found are
> initialized. On eal_cleanup(), the inverse does not happen, meaning any
> allocated memory and other configuration will not be cleaned up
> appropriately on exit.
> 
> Currently, in order for device cleanup to take place, applications must
> call the driver-relevant functions to ensure proper cleanup is done before
> the application exits. Since initialization occurs for all devices on the
> bus, not just the devices used by an application, it requires a)
> application awareness of all bus devices that could have been probed on the
> system, and b) code duplication across applications to ensure cleanup is
> performed. An example of this is rte_eth_dev_close() which is commonly used
> across the example applications.
> 
> This patch proposes adding bus cleanup to the eal_cleanup() to make EAL's
> init/exit more symmetrical, ensuring all bus devices are cleaned up
> appropriately without the application needing to be aware of all bus types
> that may have been probed during initialization.
> 
> Contained in this patch are the changes required to perform cleanup for
> devices on the PCI bus and VDEV bus during eal_cleanup(). There would be an
> ask for bus maintainers to add the relevant cleanup for their buses since
> they have the domain expertise.
> 
> Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
> Acked-by: Morten Brørup <mb@smartsharesystems.com>
> 

Thanks for the non-RFC versions. Some comments inline.

/Bruce

> ---
> v2:
> * change log level from INFO to DEBUG for PCI cleanup
> * add abignore entries for rte_bus related false positives
> 
> v3:
> * add vdev bus cleanup

Missing v4 update note.
Please reverse the order here, so it goes from newest to oldest, so those
of us tracking the patch can just look at top entry. 

> ---
>  devtools/libabigail.abignore    |  9 +++++++++
>  drivers/bus/pci/pci_common.c    | 32 ++++++++++++++++++++++++++++++++
>  drivers/bus/vdev/vdev.c         | 23 +++++++++++++++++++++++
>  lib/eal/common/eal_common_bus.c | 18 ++++++++++++++++++
>  lib/eal/include/rte_bus.h       | 23 +++++++++++++++++++++++
>  lib/eal/linux/eal.c             |  1 +
>  6 files changed, 106 insertions(+)
> 
> diff --git a/devtools/libabigail.abignore b/devtools/libabigail.abignore
> index 79ff15dc4e..3e519ee42a 100644
> --- a/devtools/libabigail.abignore
> +++ b/devtools/libabigail.abignore
> @@ -56,3 +56,12 @@
>  ; Ignore libabigail false-positive in clang builds, after moving code.
>  [suppress_function]
>  	name = rte_eal_remote_launch
> +
> +; Ignore field inserted to rte_bus, adding cleanup function
> +[suppress_type]
> +        name = rte_bus
> +        has_data_member_inserted_at = end
> +
> +; Ignore changes to internally used structs containing rte_bus
> +[suppress_type]
> +        name = rte_pci_bus, rte_vmbus_bus, rte_vdev_bus
> diff --git a/drivers/bus/pci/pci_common.c b/drivers/bus/pci/pci_common.c
> index 37ab879779..7d0c49f073 100644
> --- a/drivers/bus/pci/pci_common.c
> +++ b/drivers/bus/pci/pci_common.c
> @@ -394,6 +394,37 @@ pci_probe(void)
>  	return (probed && probed == failed) ? -1 : 0;
>  }
>  
> +static int
> +pci_cleanup(void)
> +{
> +	struct rte_pci_device *dev = NULL;
> +	int ret = 0;
> +
> +	FOREACH_DEVICE_ON_PCIBUS(dev) {
> +		struct rte_pci_addr *loc = &dev->addr;
> +		struct rte_pci_driver *drv = dev->driver;
> +
> +		if (loc == NULL || drv == NULL)
> +			continue;
> +
> +		RTE_LOG(DEBUG, EAL,
> +				"Clean up PCI driver: %s (%x:%x) device: "PCI_PRI_FMT" (socket %i)\n",
> +				drv->driver.name, dev->id.vendor_id, dev->id.device_id,
> +				loc->domain, loc->bus, loc->devid, loc->function,
> +				dev->device.numa_node);
> +
> +		ret = drv->remove(dev);
> +		if (ret < 0) {
> +			RTE_LOG(ERR, EAL, "Cleanup for device "PCI_PRI_FMT" failed\n",
> +					dev->addr.domain, dev->addr.bus, dev->addr.devid,
> +					dev->addr.function);
> +			rte_errno = errno;
> +		}
> +	}
> +
> +	return ret;
> +}

This function returns the status of the last remove call only, which is
probably not what we want. Better to make "ret" a local variable inside the
loop and have a new variable in function scope called "error", initialized
to zero. Then where you assign rte_errno you can also assign error to -1
and return error from the function at end.

> +
>  /* dump one device */
>  static int
>  pci_dump_one_device(FILE *f, struct rte_pci_device *dev)
> @@ -813,6 +844,7 @@ struct rte_pci_bus rte_pci_bus = {
>  	.bus = {
>  		.scan = rte_pci_scan,
>  		.probe = pci_probe,
> +		.cleanup = pci_cleanup,
>  		.find_device = pci_find_device,
>  		.plug = pci_plug,
>  		.unplug = pci_unplug,
> diff --git a/drivers/bus/vdev/vdev.c b/drivers/bus/vdev/vdev.c
> index a8d8b2327e..eca1a3d536 100644
> --- a/drivers/bus/vdev/vdev.c
> +++ b/drivers/bus/vdev/vdev.c
> @@ -569,6 +569,28 @@ vdev_probe(void)
>  	return ret;
>  }
>  
> +static int
> +vdev_cleanup(void)
> +{
> +	struct rte_vdev_device *dev;
> +	int ret = 0;
> +
> +	TAILQ_FOREACH(dev, &vdev_device_list, next) {
> +		const char *name;
> +		struct rte_vdev_driver *drv;
> +
> +		name = rte_vdev_device_name(dev);
> +		if (vdev_parse(name, &drv))
> +			continue;
> +
> +		ret = drv->remove(dev);
> +		if (ret < 0)
> +			VDEV_LOG(ERR, "Cleanup for device %s failed\n", rte_vdev_device_name(dev));
> +	}
> +
> +	return ret;
> +}

Same comment for ret as above.

> +
>  struct rte_device *
>  rte_vdev_find_device(const struct rte_device *start, rte_dev_cmp_t cmp,
>  		     const void *data)
> @@ -627,6 +649,7 @@ vdev_get_iommu_class(void)
>  static struct rte_bus rte_vdev_bus = {
>  	.scan = vdev_scan,
>  	.probe = vdev_probe,
> +	.cleanup = vdev_cleanup,
>  	.find_device = rte_vdev_find_device,
>  	.plug = vdev_plug,
>  	.unplug = vdev_unplug,
> diff --git a/lib/eal/common/eal_common_bus.c b/lib/eal/common/eal_common_bus.c
> index baa5b532af..046a06a2bf 100644
> --- a/lib/eal/common/eal_common_bus.c
> +++ b/lib/eal/common/eal_common_bus.c
> @@ -85,6 +85,24 @@ rte_bus_probe(void)
>  	return 0;
>  }
>  
> +/* Clean up all devices of all buses */
> +int
> +rte_bus_cleanup(void)
> +{
> +	int ret;
> +	struct rte_bus *bus;
> +
> +	TAILQ_FOREACH(bus, &rte_bus_list, next) {
> +		if (bus->cleanup == NULL)
> +			continue;
> +		ret = bus->cleanup();
> +		if (ret)
> +			RTE_LOG(ERR, EAL, "Bus (%s) cleanup failed.\n", bus->name);

Is this error message needed, if the individual buses all print out their
own failure logs? Probably harmless enough.

> +	}
> +
> +	return 0;

Do you want to pass back up the fact that a bus cleanup failed rather than
always returning 0?

> +}
> +
>  /* Dump information of a single bus */
>  static int
>  bus_dump_one(FILE *f, struct rte_bus *bus)
> diff --git a/lib/eal/include/rte_bus.h b/lib/eal/include/rte_bus.h
> index bbbb6efd28..42da38730f 100644
> --- a/lib/eal/include/rte_bus.h
> +++ b/lib/eal/include/rte_bus.h
> @@ -66,6 +66,18 @@ typedef int (*rte_bus_scan_t)(void);
>   */
>  typedef int (*rte_bus_probe_t)(void);
>  
> +/**
> + * Implementation specific cleanup function which is responsible for cleaning up
> + * devices on that bus with applicable drivers.
> + *
> + * This is called while iterating over each registered bus.
> + *
> + * @return
> + * 0 for successful cleanup
> + * !0 for any error during cleanup
> + */
> +typedef int (*rte_bus_cleanup_t)(void);
> +
>  /**
>   * Device iterator to find a device on a bus.
>   *
> @@ -277,6 +289,7 @@ struct rte_bus {
>  				/**< handle hot-unplug failure on the bus */
>  	rte_bus_sigbus_handler_t sigbus_handler;
>  					/**< handle sigbus error on the bus */
> +	rte_bus_cleanup_t cleanup;   /**< Cleanup devices on bus */
>  
>  };
>  
> @@ -317,6 +330,16 @@ int rte_bus_scan(void);
>   */
>  int rte_bus_probe(void);
>  
> +/**
> + * For each device on the buses, perform a driver 'match' and call the
> + * driver-specific function for device cleanup.
> + *
> + * @return
> + * 0 for successful match/cleanup
> + * !0 otherwise
> + */
> +int rte_bus_cleanup(void);
> +

This is in a public header file, so it's visible to users, but it's not in
the version.map file, so not actually usable by anything other than EAL. We
need to decide whether to make this function explicitly public (in which
case it probably needs to be marked as experimental and added to
version.map), or to decide its for EAL use only, in which case move the
defintion to a private header file e.g. eal_private.h.

>  /**
>   * Dump information of all the buses registered with EAL.
>   *
> diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
> index 1ef263434a..27014fdc27 100644
> --- a/lib/eal/linux/eal.c
> +++ b/lib/eal/linux/eal.c
> @@ -1266,6 +1266,7 @@ rte_eal_cleanup(void)
>  	vfio_mp_sync_cleanup();
>  #endif
>  	rte_mp_channel_cleanup();
> +	rte_bus_cleanup();
>  	/* after this point, any DPDK pointers will become dangling */
>  	rte_eal_memory_detach();
>  	eal_mp_dev_hotplug_cleanup();
> -- 
> 2.31.1
>