Hi Andy,
> Some of the fwnode APIs might return an error pointer instead of NULL
> or valid fwnode handle. The result of such API call may be considered
> optional and hence the test for it is usually done in a form of
>
> fwnode = fwnode_find_reference(...);
> if (IS_ERR(fwnode))
> ...error handling...
>
> Nevertheless the resulting fwnode may have bumped the reference count
> and hence caller of the above API is obliged to call fwnode_handle_put().
> Since fwnode may be not valid either as NULL or error pointer the check
> has to be performed there. This approach uglifies the code and adds
> a point of making a mistake, i.e. forgetting about error point case.
>
> To prevent this, allow an error pointer to be passed to the fwnode APIs.
>
> Fixes: 83b34afb6b79 ("device property: Introduce fwnode_find_reference()")
> Reported-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Tested-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
> Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Acked-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
This breaks SFP/phylink (using the lan966x switch) on my board. See below
for more details.
[..]
> @@ -480,15 +485,16 @@ int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode,
> {
> int ret;
>
> + if (IS_ERR_OR_NULL(fwnode))
> + return -ENOENT;
> +
> ret = fwnode_call_int_op(fwnode, get_reference_args, prop, nargs_prop,
> nargs, index, args);
> + if (ret == 0)
Should this be "if (ret == 0 || IS_ERR_OR_NULL(fwnode->secondary))" ?
> + return ret;
>
> - if (ret < 0 && !IS_ERR_OR_NULL(fwnode) &&
> - !IS_ERR_OR_NULL(fwnode->secondary))
> - ret = fwnode_call_int_op(fwnode->secondary, get_reference_args,
> - prop, nargs_prop, nargs, index, args);
> -
> - return ret;
> + return fwnode_call_int_op(fwnode->secondary, get_reference_args, prop, nargs_prop,
> + nargs, index, args);
> }
> EXPORT_SYMBOL_GPL(fwnode_property_get_reference_args);
What happens before this patch is that sfp_bus_find_fwnode() will call
fwnode_property_get_reference_args() and the first calls return -ENOENT
which sfp_bus_find_fwnode() will handle in a special way. After your
patch, -EINVAL is returned, because fwnode_call_int_op() on
fwnode->secondary is always called regardless of the return value of
the original fwnode.
-michael
