[dpdk-dev] [PATCH 7/9] bus: add helper to find a bus from a device name

[Jan Blunck]

On Wed, Jun 7, 2017 at 10:03 PM, Gaëtan Rivet <gaetan.rivet at 6wind.com> wrote:
> On Wed, Jun 07, 2017 at 07:28:07PM +0200, Jan Blunck wrote:
>> On Wed, May 24, 2017 at 5:12 PM, Gaetan Rivet <gaetan.rivet at 6wind.com> wrote:
>> > Find which bus should be able to parse this device name into an internal
>> > device representation.
>> >
>>
>> No, please don't add this. One should know to what bus a device
>> belongs to before plugging it. Artificially encoding the parent bus
>> into the device name is not the right thing to do. Please keep those
>> things separate.
>>
>

When plugging a device the users know about:
- bus name
- device name

Its not the case that the users invent the device names out of thin
air. The EAL shouldn't codify what the users of the EAL already know
about.


> The EAL has no way to know this currently. As you noted, it has to know
> onto which bus a device belongs before plugging it.
>
>> > Signed-off-by: Gaetan Rivet <gaetan.rivet at 6wind.com>
>> > ---
>> >  lib/librte_eal/bsdapp/eal/rte_eal_version.map   |  1 +
>> >  lib/librte_eal/common/eal_common_bus.c          | 15 +++++++++++++++
>> >  lib/librte_eal/common/include/rte_bus.h         | 12 ++++++++++++
>> >  lib/librte_eal/linuxapp/eal/rte_eal_version.map |  1 +
>> >  4 files changed, 29 insertions(+)
>> >
>> > diff --git a/lib/librte_eal/bsdapp/eal/rte_eal_version.map b/lib/librte_eal/bsdapp/eal/rte_eal_version.map
>> > index 3517d74..04fa882 100644
>> > --- a/lib/librte_eal/bsdapp/eal/rte_eal_version.map
>> > +++ b/lib/librte_eal/bsdapp/eal/rte_eal_version.map
>> > @@ -202,5 +202,6 @@ DPDK_17.08 {
>> >         global:
>> >
>> >         rte_bus_from_name;
>> > +       rte_bus_from_dev;
>> >
>> >  } DPDK_17.05;
>> > diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
>> > index 7977190..08fff60 100644
>> > --- a/lib/librte_eal/common/eal_common_bus.c
>> > +++ b/lib/librte_eal/common/eal_common_bus.c
>> > @@ -242,3 +242,18 @@ rte_bus_from_name(const char *str)
>> >                 return NULL;
>> >         return rte_bus_find(bus_cmp_name, str);
>> >  }
>> > +
>> > +static int
>> > +bus_can_parse(const struct rte_bus *bus, const void *_name)
>> > +{
>> > +       const char *name = _name;
>> > +
>> > +       return (bus->parse && !bus->parse(name, NULL));
>> > +}
>> > +
>> > +/* find a bus capable of parsing a device description */
>> > +struct rte_bus *
>> > +rte_bus_from_dev(const char *str)
>> > +{
>> > +       return rte_bus_find(bus_can_parse, str);
>> > +}
>> > diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
>> > index 5b87ac4..0b48e66 100644
>> > --- a/lib/librte_eal/common/include/rte_bus.h
>> > +++ b/lib/librte_eal/common/include/rte_bus.h
>> > @@ -251,6 +251,18 @@ struct rte_bus *rte_bus_find_by_device(const struct rte_device *dev);
>> >  struct rte_bus *rte_bus_from_name(const char *str);
>> >
>> >  /**
>> > + * Find a bus capable of identifying a device.
>> > + *
>> > + * @param str
>> > + *   A device identifier (PCI address, virtual PMD name, ...).
>> > + *
>> > + * @return
>> > + *   A valid bus structure if found.
>> > + *   NULL if no bus is able to parse this device.
>> > + */
>> > +struct rte_bus *rte_bus_from_dev(const char *str);
>> > +
>> > +/**
>> >   * Helper for Bus registration.
>> >   * The constructor has higher priority than PMD constructors.
>> >   */
>> > diff --git a/lib/librte_eal/linuxapp/eal/rte_eal_version.map b/lib/librte_eal/linuxapp/eal/rte_eal_version.map
>> > index 6607acc..a5127d6 100644
>> > --- a/lib/librte_eal/linuxapp/eal/rte_eal_version.map
>> > +++ b/lib/librte_eal/linuxapp/eal/rte_eal_version.map
>> > @@ -206,5 +206,6 @@ DPDK_17.08 {
>> >         global:
>> >
>> >         rte_bus_from_name;
>> > +       rte_bus_from_dev;
>> >
>> >  } DPDK_17.05;
>> > --
>> > 2.1.4
>> >
>
> --
> Gaėtan Rivet
> 6WIND