Re: [dpdk-dev] [PATCH v1] eal: add manual probing option

["Gaëtan Rivet" <gaetan.rivet@6wind.com>]

On Mon, Sep 30, 2019 at 01:51:35PM -0400, Aaron Conole wrote:
> Gaetan Rivet <gaetan.rivet@6wind.com> writes:
> 
> > Add a new EAL option enabling manual probing in the EAL.
> > This command line option will configure the EAL so that buses
> > will not trigger their probe step on their own.
> >
> > Applications are then expected to hotplug devices as they see fit.
> >
> > Devices declared on the command line by the user (using -w and --vdev),
> > will be probed using the hotplug API, in the order they are declared.
> >
> > This has the effect of offering a way for users to control probe order
> > of their devices, for drivers requiring it.
> >
> > Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
> > ---
> >
> > I haven't heard many opinions on the matter, please shout if you see an issue
> > with this approach.
> >
> > @Slava: I have tested rather quickly that it does not break anything,
> >         and that it works as intended for basic cases.
> >         Can you test it further for your use-case and tell me if it works fine?
> >
> > Beyond the obvious difference between both probe mode, something to keep in mind:
> > while using -w on invalid devices would not block (PCI) bus probing, it will stop manual
> > probing in its track. All devices need to exist and be valid device IDs.
> >
> >  doc/guides/rel_notes/release_19_11.rst     |  9 +++++++
> >  lib/librte_eal/common/eal_common_bus.c     |  6 +++++
> >  lib/librte_eal/common/eal_common_dev.c     | 41 ++++++++++++++++++++++++++++++
> >  lib/librte_eal/common/eal_common_options.c |  8 ++++++
> >  lib/librte_eal/common/eal_internal_cfg.h   |  1 +
> >  lib/librte_eal/common/eal_options.h        |  2 ++
> >  lib/librte_eal/common/eal_private.h        |  9 +++++++
> >  lib/librte_eal/common/include/rte_eal.h    | 17 +++++++++++++
> >  lib/librte_eal/freebsd/eal/eal.c           |  5 ++++
> >  lib/librte_eal/linux/eal/eal.c             |  5 ++++
> >  lib/librte_eal/rte_eal_version.map         |  7 +++++
> >  11 files changed, 110 insertions(+)
> >
> > diff --git a/doc/guides/rel_notes/release_19_11.rst b/doc/guides/rel_notes/release_19_11.rst
> > index 27cfbd9e3..3996e429d 100644
> > --- a/doc/guides/rel_notes/release_19_11.rst
> > +++ b/doc/guides/rel_notes/release_19_11.rst
> > @@ -56,6 +56,15 @@ New Features
> >       Also, make sure to start the actual text at the margin.
> >       =========================================================
> >  
> > +* **EAL wil now propose to enforce manual probing of devices.**
> > +
> > +  Previously, a user could not force an order when probing declared devices.
> > +  This could cause issues for drivers depending on another device being present.
> > +  A new option ``--manual-probe`` is now available to do just that.
> > +  This new option relies on the device bus supporting hotplug. It can
> > +  also be used to disable automatic probing from the ``PCI`` bus without
> > +  having to disable the whole bus.
> > +
> >  
> >  Removed Items
> >  -------------
> > diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
> > index baa5b532a..145a96812 100644
> > --- a/lib/librte_eal/common/eal_common_bus.c
> > +++ b/lib/librte_eal/common/eal_common_bus.c
> > @@ -6,6 +6,7 @@
> >  #include <string.h>
> >  #include <sys/queue.h>
> >  
> > +#include <rte_eal.h>
> >  #include <rte_bus.h>
> >  #include <rte_debug.h>
> >  #include <rte_string_fns.h>
> > @@ -63,6 +64,11 @@ rte_bus_probe(void)
> >  	int ret;
> >  	struct rte_bus *bus, *vbus = NULL;
> >  
> > +	if (rte_eal_manual_probe()) {
> > +		RTE_LOG(DEBUG, EAL, "Manual probing enabled.\n");
> > +		return rte_dev_probe_devargs_list();
> > +	}
> > +
> >  	TAILQ_FOREACH(bus, &rte_bus_list, next) {
> >  		if (!strcmp(bus->name, "vdev")) {
> >  			vbus = bus;
> > diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
> > index 9e4f09d83..3b7769a3c 100644
> > --- a/lib/librte_eal/common/eal_common_dev.c
> > +++ b/lib/librte_eal/common/eal_common_dev.c
> > @@ -109,6 +109,47 @@ build_devargs(const char *busname, const char *devname,
> >  }
> >  
> >  int
> > +rte_dev_probe_devargs_list(void)
> > +{
> > +	struct rte_device *dev;
> > +	struct rte_devargs *da;
> > +	int ret;
> > +
> > +	RTE_EAL_DEVARGS_FOREACH(NULL, da) {
> > +		dev = da->bus->find_device(NULL, cmp_dev_name, da->name);
> > +		if (dev == NULL) {
> > +			RTE_LOG(ERR, EAL, "Unable to find device %s on bus %s\n",
> > +				da->name, da->bus->name);
> > +			continue;
> > +		}
> > +
> > +		if (rte_dev_is_probed(dev))
> > +			continue;
> > +
> > +		if (dev->bus->plug == NULL) {
> > +			RTE_LOG(ERR, EAL, "Manual probing (hotplug) not supported by bus %s, "
> > +					  "required by device %s\n",
> > +				dev->bus->name, dev->name);
> > +			continue;
> > +		}
> > +
> > +		ret = dev->bus->plug(dev);
> > +		/* Ignore positive return values, they are possibly
> > +		 * triggered by blacklisted devices on the PCI bus. Probing
> > +		 * should then continue.
> > +		 */
> > +		if (ret < 0 || !rte_dev_is_probed(dev)) {
> > +			RTE_LOG(ERR, EAL, "Driver cannot attach device %s\n",
> > +				dev->name);
> > +			/* Fail on first real probe error. */
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +int
> >  rte_eal_hotplug_add(const char *busname, const char *devname,
> >  		    const char *drvargs)
> >  {
> > diff --git a/lib/librte_eal/common/eal_common_options.c b/lib/librte_eal/common/eal_common_options.c
> > index 05cae5f75..66c232b14 100644
> > --- a/lib/librte_eal/common/eal_common_options.c
> > +++ b/lib/librte_eal/common/eal_common_options.c
> > @@ -81,6 +81,7 @@ eal_long_options[] = {
> >  	{OPT_LEGACY_MEM,        0, NULL, OPT_LEGACY_MEM_NUM       },
> >  	{OPT_SINGLE_FILE_SEGMENTS, 0, NULL, OPT_SINGLE_FILE_SEGMENTS_NUM},
> >  	{OPT_MATCH_ALLOCATIONS, 0, NULL, OPT_MATCH_ALLOCATIONS_NUM},
> > +	{OPT_MANUAL_PROBE,      0, NULL, OPT_MANUAL_PROBE_NUM     },
> >  	{0,                     0, NULL, 0                        }
> >  };
> >  
> > @@ -1408,6 +1409,9 @@ eal_parse_common_option(int opt, const char *optarg,
> >  			return -1;
> >  		}
> >  		break;
> > +	case OPT_MANUAL_PROBE_NUM:
> > +		conf->manual_probe = 1;
> > +		break;
> >  
> >  	/* don't know what to do, leave this to caller */
> >  	default:
> > @@ -1634,6 +1638,10 @@ eal_common_usage(void)
> >  	       "  --"OPT_VDEV"              Add a virtual device.\n"
> >  	       "                      The argument format is <driver><id>[,key=val,...]\n"
> >  	       "                      (ex: --vdev=net_pcap0,iface=eth2).\n"
> > +	       "  --"OPT_MANUAL_PROBE"      Enable manual probing.\n"
> > +	       "                      Disable probe step for all buses.\n"
> > +	       "                      Devices will need to be probed using the hotplug API.\n"
> > +	       "                      PCI and vdev declarations will be treated in order as hotplug commands.\n"
> >  	       "  --"OPT_IOVA_MODE"   Set IOVA mode. 'pa' for IOVA_PA\n"
> >  	       "                      'va' for IOVA_VA\n"
> >  	       "  -d LIB.so|DIR       Add a driver or driver directory\n"
> > diff --git a/lib/librte_eal/common/eal_internal_cfg.h b/lib/librte_eal/common/eal_internal_cfg.h
> > index a42f34923..0006f903f 100644
> > --- a/lib/librte_eal/common/eal_internal_cfg.h
> > +++ b/lib/librte_eal/common/eal_internal_cfg.h
> > @@ -44,6 +44,7 @@ struct internal_config {
> >  	unsigned hugepage_unlink;         /**< true to unlink backing files */
> >  	volatile unsigned no_pci;         /**< true to disable PCI */
> >  	volatile unsigned no_hpet;        /**< true to disable HPET */
> > +	volatile unsigned manual_probe;   /**< true to enable manual device probing. */
> >  	volatile unsigned vmware_tsc_map; /**< true to use VMware TSC mapping
> >  										* instead of native TSC */
> >  	volatile unsigned no_shconf;      /**< true if there is no shared config */
> > diff --git a/lib/librte_eal/common/eal_options.h b/lib/librte_eal/common/eal_options.h
> > index 9855429e5..588fa32a6 100644
> > --- a/lib/librte_eal/common/eal_options.h
> > +++ b/lib/librte_eal/common/eal_options.h
> > @@ -69,6 +69,8 @@ enum {
> >  	OPT_IOVA_MODE_NUM,
> >  #define OPT_MATCH_ALLOCATIONS  "match-allocations"
> >  	OPT_MATCH_ALLOCATIONS_NUM,
> > +#define OPT_MANUAL_PROBE "manual-probe"
> > +	OPT_MANUAL_PROBE_NUM,
> >  	OPT_LONG_MAX_NUM
> >  };
> >  
> > diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
> > index 798ede553..fd7ac8e37 100644
> > --- a/lib/librte_eal/common/eal_private.h
> > +++ b/lib/librte_eal/common/eal_private.h
> > @@ -381,4 +381,13 @@ rte_option_init(void);
> >  void
> >  rte_option_usage(void);
> >  
> > +/**
> > + * Go through the devargs list and probe everything in order.
> > + *
> > + * @return
> > + *   0 on success, negative on error.
> > + */
> > +int
> > +rte_dev_probe_devargs_list(void);
> > +
> >  #endif /* _EAL_PRIVATE_H_ */
> > diff --git a/lib/librte_eal/common/include/rte_eal.h b/lib/librte_eal/common/include/rte_eal.h
> > index b7cf91214..bd9087bcc 100644
> > --- a/lib/librte_eal/common/include/rte_eal.h
> > +++ b/lib/librte_eal/common/include/rte_eal.h
> > @@ -465,6 +465,23 @@ int rte_eal_has_hugepages(void);
> >  int rte_eal_has_pci(void);
> >  
> >  /**
> > + * Whether EAL probe is manual.
> > + * Enabled by the --manual-probe option.
> > + *
> > + * When manual probing is enabled, batched bus probe of
> > + * their devices is disabled. All devices need to be probed
> > + * using the proper rte_dev API.
> > + *
> > + * In this mode, devices declared on the command line will
> > + * be probed using the bus hotplug API. It is used to enforce
> > + * a specific probe order.
> > + *
> > + * @return
> > + *   Nonzero if manual device probing is enabled.
> > + */
> > +int rte_eal_manual_probe(void);
> > +
> > +/**
> >   * Whether the EAL was asked to create UIO device.
> >   *
> >   * @return
> > diff --git a/lib/librte_eal/freebsd/eal/eal.c b/lib/librte_eal/freebsd/eal/eal.c
> > index d53f0fe69..2daa63b23 100644
> > --- a/lib/librte_eal/freebsd/eal/eal.c
> > +++ b/lib/librte_eal/freebsd/eal/eal.c
> > @@ -961,6 +961,11 @@ int rte_eal_has_pci(void)
> >  	return !internal_config.no_pci;
> >  }
> >  
> > +int rte_eal_manual_probe(void)
> > +{
> > +	return internal_config.manual_probe;
> > +}
> > +
> >  int rte_eal_create_uio_dev(void)
> >  {
> >  	return internal_config.create_uio_dev;
> > diff --git a/lib/librte_eal/linux/eal/eal.c b/lib/librte_eal/linux/eal/eal.c
> > index 946222ccd..476fc2e4a 100644
> > --- a/lib/librte_eal/linux/eal/eal.c
> > +++ b/lib/librte_eal/linux/eal/eal.c
> > @@ -1376,6 +1376,11 @@ int rte_eal_create_uio_dev(void)
> >  	return internal_config.create_uio_dev;
> >  }
> >  
> > +int rte_eal_manual_probe(void)
> > +{
> > +	return internal_config.manual_probe;
> > +}
> > +
> >  enum rte_intr_mode
> >  rte_eal_vfio_intr_mode(void)
> >  {
> > diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
> > index 7cbf82d37..fe5395c24 100644
> > --- a/lib/librte_eal/rte_eal_version.map
> > +++ b/lib/librte_eal/rte_eal_version.map
> > @@ -312,6 +312,13 @@ DPDK_19.08 {
> >  
> >  } DPDK_19.05;
> >  
> > +DPDK_19.05 {
> > +	global:
> > +
> > +	rte_eal_manual_probe
> 
> Syntax error - needs a ';' at the end of this symbol.
> 

Ah yes, sorry.
I'm thinking there is a script or a validation tool using this, I should try it.

> > +
> > +} DPDK_19.11;
> > +
> >  EXPERIMENTAL {
> >  	global:

-- 
Gaëtan Rivet
6WIND