Re: [dpdk-dev] [PATCH 1/2] usertools/devbind: add error on forgetting to specify driver

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 24 Jul 2019 16:34:43 +0100
Anatoly Burakov <anatoly.burakov@intel.com> wrote:

> A common user error is to forget driver to which the PCI devices should
> be bound to. Currently, the error message in this case looks unhelpful
> misleading and indecipherable to anyone but people who know how devbind
> works.
> 
> Fix this by checking if the driver string is actually a valid device
> string. If it is, we assume that the user has just forgot to specify the
> driver, and display appropriate error. We also assume that no one will
> name their driver in a format that looks like a PCI address, but that
> seems like a reasonable assumption to make.
> 
> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
>  usertools/dpdk-devbind.py | 33 ++++++++++++++++++++++++++++-----
>  1 file changed, 28 insertions(+), 5 deletions(-)
> 
> diff --git a/usertools/dpdk-devbind.py b/usertools/dpdk-devbind.py
> index 542ecffcc..f7c4c6434 100755
> --- a/usertools/dpdk-devbind.py
> +++ b/usertools/dpdk-devbind.py
> @@ -342,9 +342,8 @@ def dev_id_from_dev_name(dev_name):
>              if dev_name in devices[d]["Interface"].split(","):
>                  return devices[d]["Slot"]
>      # if nothing else matches - error
> -    print("Unknown device: %s. "
> -          "Please specify device in \"bus:slot.func\" format" % dev_name)
> -    sys.exit(1)
> +    raise ValueError("Unknown device: %s. "
> +	    "Please specify device in \"bus:slot.func\" format" % dev_name)
>  
>  
>  def unbind_one(dev_id, force):
> @@ -493,7 +492,12 @@ def unbind_all(dev_list, force=False):
>                      unbind_one(devices[d]["Slot"], force)
>          return
>  
> -    dev_list = map(dev_id_from_dev_name, dev_list)
> +    try:
> +        dev_list = map(dev_id_from_dev_name, dev_list)
> +    except ValueError as ex:
> +        print(ex)
> +        sys.exit(1)
> +
>      for d in dev_list:
>          unbind_one(d, force)
>  
> @@ -502,7 +506,26 @@ def bind_all(dev_list, driver, force=False):
>      """Bind method, takes a list of device locations"""
>      global devices
>  
> -    dev_list = map(dev_id_from_dev_name, dev_list)
> +    # a common user error is to forget to specify the driver the devices need to
> +    # be bound to. check if the driver is a valid device, and if it is, show
> +    # a meaningful error.
> +    try:
> +        dev_id_from_dev_name(driver)
> +        # if we've made it this far, this means that the "driver" was a valid
> +        # device string, so it's probably not a valid driver name.
> +        print("ERROR: Driver '%s' does not look like a valid driver. "
> +              "Did you forget to specify the driver to bind devices to?" %
> +              driver)
> +        sys.exit(1)
> +    except ValueError:
> +        # driver generated error - it's not a valid device ID, so all is well
> +        pass
> +
> +    try:
> +        dev_list = map(dev_id_from_dev_name, dev_list)
> +    except ValueError as ex:
> +        print(ex)
> +        sys.exit(1)
>  
>      for d in dev_list:
>          bind_one(d, driver, force)

It would be better print error messages to stderr.
If you call sys.exit() with a string it will do that.