On Fri, Aug 09, 2024 at 05:42:32PM +0300, Dan Carpenter wrote:
> On Thu, Aug 08, 2024 at 11:46:11AM +0200, Christophe JAILLET wrote:
> > Use sysfs_emit_at() instead of snprintf() + custom logic.
> > Using sysfs_emit_at() is much more simple.
> >
> > Also, sysfs_emit() is already used in this function, so using
> > sysfs_emit_at() is more consistent.
> >
> > Also simplify the logic:
> > - always add a space after an entry
> > - change the last space into a '\n'
> >
> > Finally it is easy to see that, given the size of cabc_modes, PAGE_SIZE
> > can not be reached.
> > So better keep everything simple (and correct).
> >
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > .../omap2/omapfb/displays/panel-sony-acx565akm.c | 15 ++++++++-------
> > 1 file changed, 8 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/omap2/omapfb/displays/panel-sony-acx565akm.c b/drivers/video/fbdev/omap2/omapfb/displays/panel-sony-acx565akm.c
> > index 71d2e015960c..fc975615d5c9 100644
> > --- a/drivers/video/fbdev/omap2/omapfb/displays/panel-sony-acx565akm.c
> > +++ b/drivers/video/fbdev/omap2/omapfb/displays/panel-sony-acx565akm.c
> > @@ -466,19 +466,20 @@ static ssize_t show_cabc_available_modes(struct device *dev,
> > char *buf)
> > {
> > struct panel_drv_data *ddata = dev_get_drvdata(dev);
> > - int len;
> > + int len = 0;
> > int i;
> >
> > if (!ddata->has_cabc)
> > return sysfs_emit(buf, "%s\n", cabc_modes[0]);
> >
> > - for (i = 0, len = 0;
> > - len < PAGE_SIZE && i < ARRAY_SIZE(cabc_modes); i++)
> > - len += snprintf(&buf[len], PAGE_SIZE - len, "%s%s%s",
> > - i ? " " : "", cabc_modes[i],
> > - i == ARRAY_SIZE(cabc_modes) - 1 ? "\n" : "");
> > + for (i = 0; i < ARRAY_SIZE(cabc_modes); i++)
> > + len += sysfs_emit_at(buf, len, "%s ", cabc_modes[i]);
> > +
> > + /* Remove the trailing space */
> > + if (len)
> > + buf[len - 1] = '\n';
>
> I'm uncomfortable with this line. It assumes we don't overflow PAGE_SIZE where
> the original code was careful about checking. Probably easiest to do what the
> original code did and say:
>
> for (i = 0; i < ARRAY_SIZE(cabc_modes); i++)
> len += sysfs_emit_at(buf, len, "%s%s", cabc_modes[i],
> i == ARRAY_SIZE(cabc_modes) - 1 ? "\n" : "");
Or you could change it to:
if (len)
sysfs_emit_at(buf, len - 1, "\n");
But that feels weird.
regards,
dan carpenter
