Hi Hans.
On Fri, Jul 8, 2022 at 9:28 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
On 7/8/22 20:21, Geert Uytterhoeven wrote:
If no mode name part was specified, mode_end is zero, and the "ret ==
mode_end" check does the wrong thing.
Fix this by checking for a non-zero return value instead.
Which is wrong to do, since now if you have e.g. a mode list
with:
"dblntsc",
"dblntsc-ff"
in there and the cmdline contains "dblntsc-ff" then you
will already stop with a (wrong!) match at "dblntsc".
It indeed behaves that way, and did so before, as str_has_prefix()
checks for a matching prefix, and thus may never get to the full
match. However, can we change that to an exact match, without
introducing regressions?
This can be avoided by reverse-sorting the modelist (or iterating
backwards through a sorted modelist), though.
While at it, skip all named mode handling when mode_end is zero, as it
is futile.
AFAICT, this is actually what needs to be done to fix this, while keeping
the ret == mode_end check.
"ret == mode_end" or "ret" doesn't matter (except for the special
case of mode_end is zero), as str_has_prefix() returns either zero or
the length of the prefix. Hence it never returns a non-zero value
smaller than the length of the prefix.
Fixes: 7b1cce760afe38b4 ("drm/modes: parse_cmdline: Allow specifying stand-alone options")
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_modes.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 14b746f7ba975954..30a7be97707bfb16 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1823,9 +1823,9 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
}
/* First check for a named mode */
- for (i = 0; i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
+ for (i = 0; mode_end && i < ARRAY_SIZE(drm_named_modes_whitelist); i++) {
ret = str_has_prefix(name, drm_named_modes_whitelist[i]);
- if (ret == mode_end) {
+ if (ret) {
if (refresh_ptr)
return false; /* named + refresh is invalid */
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
