Messages in this thread | | | From | Miguel Ojeda <> | Date | Fri, 23 Feb 2018 10:39:47 +0100 | Subject | Re: [PATCH 3/3] auxdisplay: img-ascii-lcd: Silence 2 uninitialized warnings |
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Hi Geert,
On Mon, Feb 19, 2018 at 7:40 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > Hi Miguel, > > On Mon, Feb 19, 2018 at 5:09 PM, Miguel Ojeda > <miguel.ojeda.sandonis@gmail.com> wrote: >> The warnings are: >> >> drivers/auxdisplay/img-ascii-lcd.c: warning: 'err' may be used >> uninitialized in this function [-Wuninitialized] >> >> At lines 109 and 207. Reported by Geert using the build service >> several times, e.g.: >> >> https://lkml.org/lkml/2018/2/19/303 >> >> They are two false positives, since num_chars > 0 in the three present >> configurations (boston, malta, sead3). Initializing to an error state by >> default silences the warning and makes the code print an error in case a >> num_chars == 0 happens in the future (unlikely, since it does not make >> sense currently). >> >> The warnings seem to disappear starting with gcc >= 4.9 >> >> Cc: Geert Uytterhoeven <geert@linux-m68k.org> >> Cc: Paul Burton <paul.burton@mips.com> >> Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> > > Thanks for your patch! > > I would initialize err to zero, though, as there is no real error condition if > called with num_char == 0.
True, it also makes sense that way. Both are fine with me. I was thinking more in the lines of "update() called for no reason (no chars) is an error".
Since it will never happen anyway and = 0 is simpler to explain (nothing to explain in the commit), I will change it for the queue. Should I add your Ack?
Thanks for taking a look! Miguel
> >> --- >> I will queue it up for 4.17. >> >> drivers/auxdisplay/img-ascii-lcd.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c >> index d8133024fd5d..bd5ebb5c516c 100644 >> --- a/drivers/auxdisplay/img-ascii-lcd.c >> +++ b/drivers/auxdisplay/img-ascii-lcd.c >> @@ -97,7 +97,7 @@ static struct img_ascii_lcd_config boston_config = { >> static void malta_update(struct img_ascii_lcd_ctx *ctx) >> { >> unsigned int i; >> - int err; >> + int err = 1; >> >> for (i = 0; i < ctx->cfg->num_chars; i++) { >> err = regmap_write(ctx->regmap, >> @@ -180,7 +180,7 @@ static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx) >> static void sead3_update(struct img_ascii_lcd_ctx *ctx) >> { >> unsigned int i; >> - int err; >> + int err = 1; >> >> for (i = 0; i < ctx->cfg->num_chars; i++) { >> err = sead3_wait_lcd_idle(ctx); > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > 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
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