[PATCH] fdtdec: use full path in fdtdec_get_alias_seq comparison

[Simon Glass]

Hi Vladimir,

On Fri, 27 Mar 2020 at 11:29, Vladimir Oltean <olteanv at gmail.com> wrote:
>
> From: Vladimir Oltean <vladimir.oltean at nxp.com>
>
> Currently fdtdec_get_alias_seq() calls fdt_get_name() which returns only
> the name of the leaf node. So it needs to also trim the path of the
> alias to the leaf name only, leading to imperfect matches.
>
> This means that the following aliases:
>
>     /aliases {
>         eth0 = "/dspi at 2120000/ethernet-switch at 0/ports/port at 0";
>         eth1 = "/pcie at 1f0000000/pci at 0,5/ports/port at 0";
>     };
>
> will make fdtdec_get_alias_seq to return a seq of zero for both aliases,
> as the match will only take place on the "port at 0" portion.
>
> Fix this by calling fdt_get_path and comparing the full path of the
> alias.
>
> Fixes: 5c33c9fdbb3f ("fdt: Add a function to get the alias sequence of a node")
> Signed-off-by: Vladimir Oltean <vladimir.oltean at nxp.com>
> ---
>  lib/fdtdec.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/lib/fdtdec.c b/lib/fdtdec.c
> index eb11fc898e30..55c1b36e823b 100644
> --- a/lib/fdtdec.c
> +++ b/lib/fdtdec.c
> @@ -455,13 +455,14 @@ int fdtdec_get_alias_seq(const void *blob, const char *base, int offset,
>                          int *seqp)
>  {
>         int base_len = strlen(base);
> -       const char *find_name;
> -       int find_namelen;
>         int prop_offset;
> +       char path[64];
> +       int path_len;
>         int aliases;
>
> -       find_name = fdt_get_name(blob, offset, &find_namelen);
> -       debug("Looking for '%s' at %d, name %s\n", base, offset, find_name);
> +       fdt_get_path(blob, offset, path, sizeof(path));

This is really slow. I would prefer not to change this for what seems
like an odd case.

Can you enable CONFIG_OF_LIVE instead?

> +       path_len = strlen(path);
> +       debug("Looking for '%s' at %d, path %s\n", base, offset, path);
>
>         aliases = fdt_path_offset(blob, "/aliases");
>         for (prop_offset = fdt_first_property_offset(blob, aliases);
> @@ -469,17 +470,15 @@ int fdtdec_get_alias_seq(const void *blob, const char *base, int offset,
>              prop_offset = fdt_next_property_offset(blob, prop_offset)) {
>                 const char *prop;
>                 const char *name;
> -               const char *slash;
>                 int len, val;
>
>                 prop = fdt_getprop_by_offset(blob, prop_offset, &name, &len);
>                 debug("   - %s, %s\n", name, prop);
> -               if (len < find_namelen || *prop != '/' || prop[len - 1] ||
> +               if (len < path_len || *prop != '/' || prop[len - 1] ||
>                     strncmp(name, base, base_len))
>                         continue;
>
> -               slash = strrchr(prop, '/');
> -               if (strcmp(slash + 1, find_name))
> +               if (strcmp(prop, path))
>                         continue;
>                 val = trailing_strtol(name);
>                 if (val != -1) {
> --
> 2.17.1
>

Regards,
Simon