On Fri, 2022-03-04 at 19:32 +0200, Andy Shevchenko wrote:
> 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_OR_NULL(fwnode))
> ...error handling...
>
> Nevertheless the resulting fwnode may have bumped 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 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>
> ---
>
> v2: adjusted the entire fwnode API (Sakari)
>
> Nuno, can you test this with the ltc2983 series, including the
> IS_ERR_OR_NULL()
> fix to it?
>
Sure... I will test that series together with this patch.
> drivers/base/property.c | 45 +++++++++++++++++++++++++--------------
> --
> include/linux/fwnode.h | 10 ++++-----
> 2 files changed, 33 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index c0e94cce9c29..1922818470b0 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -9,6 +9,7 @@
>
> #include <linux/acpi.h>
> #include <linux/export.h>
> +#include <linux/fwnode.h>
> #include <linux/kernel.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> @@ -45,14 +46,16 @@ EXPORT_SYMBOL_GPL(device_property_present);
> bool fwnode_property_present(const struct fwnode_handle *fwnode,
> const char *propname)
> {
> - bool ret;
> + if (IS_ERR_OR_NULL(fwnode))
> + return false;
>
> - ret = fwnode_call_bool_op(fwnode, property_present,
> propname);
> - if (ret == false && !IS_ERR_OR_NULL(fwnode) &&
> - !IS_ERR_OR_NULL(fwnode->secondary))
> - ret = fwnode_call_bool_op(fwnode->secondary,
> property_present,
> - propname);
> - return ret;
> + if (fwnode_call_bool_op(fwnode, property_present, propname))
> + return true;
> +
> + if (IS_ERR_OR_NULL(fwnode->secondary))
> + return false;
> +
> + return fwnode_call_bool_op(fwnode->secondary,
> property_present, propname);
> }
> EXPORT_SYMBOL_GPL(fwnode_property_present);
>
> @@ -232,10 +235,12 @@ static int fwnode_property_read_int_array(const
> struct fwnode_handle *fwnode,
> {
> int ret;
>
> + if (IS_ERR_OR_NULL(fwnode))
> + return -EINVAL;
> +
> ret = fwnode_call_int_op(fwnode, property_read_int_array,
> propname,
> elem_size, val, nval);
> - if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode) &&
> - !IS_ERR_OR_NULL(fwnode->secondary))
> + if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode->secondary))
> ret = fwnode_call_int_op(
> fwnode->secondary, property_read_int_array,
> propname,
> elem_size, val, nval);
> @@ -371,10 +376,12 @@ int fwnode_property_read_string_array(const
> struct fwnode_handle *fwnode,
> {
> int ret;
>
> + if (IS_ERR_OR_NULL(fwnode))
> + return -EINVAL;
> +
> ret = fwnode_call_int_op(fwnode, property_read_string_array,
> propname,
> val, nval);
> - if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode) &&
> - !IS_ERR_OR_NULL(fwnode->secondary))
> + if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode->secondary))
> ret = fwnode_call_int_op(fwnode->secondary,
> property_read_string_array,
Isn't !IS_ERR_OR_NULL(fwnode->secondary)) redundant? AFAIU,
fwnode_call_int_op() will already check the fwnode and only call the op
if the pointer is valid...
- Nuno Sá
