[RFC v3 5/7] bus: factorize devargs lookup

[David Marchand]

On Thu, 5 Mar 2026 at 18:06, Bruce Richardson
<bruce.richardson at intel.com> wrote:
>
> On Thu, Mar 05, 2026 at 05:45:47PM +0100, David Marchand wrote:
> > Each bus reimplements some similar devargs lookup code.
> >
> > The differences are in how some bus (PCI, VMBUS etc...) normalizes the
> > device names. We can't use the .parse existing handler from outside the
> > bus code itself, as the size of the bus specific device location address
> > is unknown.
> > Introduce a bus specific helper to compare two device names and
> > hide this ugly detail.
> >
> > Signed-off-by: David Marchand <david.marchand at redhat.com>
> > ---
>
> Looks generally good. Couple of minor naming suggestions inline below.
>
> Acked-by: Bruce Richardson <bruce.richardson at intel.com>
>
>
> >  drivers/bus/auxiliary/auxiliary_common.c | 16 ++-------
> >  drivers/bus/cdx/cdx.c                    | 14 +-------
> >  drivers/bus/dpaa/dpaa_bus.c              | 41 +++++++++++++-----------
> >  drivers/bus/fslmc/fslmc_bus.c            | 34 ++++++++++----------
> >  drivers/bus/pci/pci_common.c             | 38 +++++++++++-----------
> >  drivers/bus/platform/platform.c          | 17 ++--------
> >  drivers/bus/uacce/uacce.c                | 19 ++---------
> >  drivers/bus/vmbus/linux/vmbus_bus.c      |  2 +-
> >  drivers/bus/vmbus/private.h              |  3 --
> >  drivers/bus/vmbus/vmbus_common.c         | 30 ++++++++---------
> >  drivers/dma/idxd/idxd_bus.c              | 14 ++------
> >  lib/eal/common/eal_common_bus.c          | 20 ++++++++++++
> >  lib/eal/include/bus_driver.h             | 31 ++++++++++++++++++
> >  13 files changed, 132 insertions(+), 147 deletions(-)
> >
>
> <snip>
>
> > diff --git a/lib/eal/common/eal_common_bus.c b/lib/eal/common/eal_common_bus.c
> > index 0a2311a342..863c7418bb 100644
> > --- a/lib/eal/common/eal_common_bus.c
> > +++ b/lib/eal/common/eal_common_bus.c
> > @@ -8,6 +8,7 @@
> >
> >  #include <bus_driver.h>
> >  #include <rte_debug.h>
> > +#include <rte_devargs.h>
> >  #include <rte_string_fns.h>
> >  #include <rte_errno.h>
> >
> > @@ -205,6 +206,25 @@ rte_bus_find_by_name(const char *busname)
> >       return rte_bus_find(NULL, cmp_bus_name, (const void *)busname);
> >  }
> >
> > +RTE_EXPORT_INTERNAL_SYMBOL(rte_bus_find_devargs)
> > +struct rte_devargs *
> > +rte_bus_find_devargs(const struct rte_bus *bus, const char *name)
> > +{
> > +     rte_bus_devname_compare_t cmp = bus->devname_compare;
> > +     struct rte_devargs *devargs;
> > +
> > +     if (cmp == NULL)
> > +             cmp = strcmp;
> > +
> > +     RTE_EAL_DEVARGS_FOREACH(rte_bus_name(bus), devargs) {
> > +             if (cmp(name, devargs->name) != 0)
> > +                     continue;
> > +             return devargs;
> > +     }
> > +
> > +     return NULL;
> > +}
> > +
> >  static int
> >  bus_can_parse(const struct rte_bus *bus, const void *_name)
> >  {
> > diff --git a/lib/eal/include/bus_driver.h b/lib/eal/include/bus_driver.h
> > index 60527b75b6..430906772d 100644
> > --- a/lib/eal/include/bus_driver.h
> > +++ b/lib/eal/include/bus_driver.h
> > @@ -118,6 +118,21 @@ typedef int (*rte_bus_unplug_t)(struct rte_device *dev);
> >   */
> >  typedef int (*rte_bus_parse_t)(const char *name, void *addr);
> >
> > +/**
> > + * Bus specific device name comparison function.
> > + * Bus can normalize the names of devices using an internal representation.
> > + * This helper makes it possible to check whether two names refer to the same device.
> > + *
> > + * @param[in] name1
> > + *   device information location address,
> > + * @param[in] name2
> > + *   device information location address,
> > + *
> > + * @return
> > + *      true or false
> > + */
> > +typedef int (*rte_bus_devname_compare_t)(const char *name1, const char *name2);
> > +
>
> This is a good addition.
>
> >  /**
> >   * Parse bus part of the device arguments.
> >   *
> > @@ -258,6 +273,7 @@ struct rte_bus {
> >       rte_bus_plug_t plug;         /**< Probe single device for drivers */
> >       rte_bus_unplug_t unplug;     /**< Remove single device from driver */
> >       rte_bus_parse_t parse;       /**< Parse a device name */
> > +     rte_bus_devname_compare_t devname_compare; /**< Compare two device names */
> >       rte_bus_devargs_parse_t devargs_parse; /**< Parse bus devargs */
> >       rte_dev_dma_map_t dma_map;   /**< DMA map for device in the bus */
> >       rte_dev_dma_unmap_t dma_unmap; /**< DMA unmap for device in the bus */
> > @@ -281,6 +297,21 @@ struct rte_bus {
> >  __rte_internal
> >  void rte_bus_register(struct rte_bus *bus);
> >
> > +/**
> > + * Find the devargs associated to a device.
> > + *
> > + * @param bus
> > + *   A pointer to a rte_bus structure describing the bus
> > + *   to be unregistered.
> > + * @param dev_name
> > + *   A device name.
> > + *
> > + * @return
> > + *   Pointer to the devargs, or NULL if none found.
> > + */
> > +__rte_internal
> > +struct rte_devargs *rte_bus_find_devargs(const struct rte_bus *bus, const char *name);
> > +
>
> The doxygen says the parameter is dev_name, while the prototype only uses
> name. I'd prefer this to be "dev_name". [I nearly one if the function
> itself should have an extra "_" and be "find_dev_args", as it's finding
> the args for a particular device, rather than finding the "devargs" for the
> bus itself.]

Good catch.

Err well, on doxygen / prototype misalignment.. documentation
generation should fail if it is not aligned.
Strange I did not see this.
Ah.. it is a driver header, so we probably don't generate any doc for this.


-- 
David Marchand