| Message ID | 20180704142255.GA8614@embeddedor.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
"Gustavo A. R. Silva" <gustavo@embeddedor.com> writes: > Add suffix ULL to constant 1000 in order to give the compiler complete > information about the proper arithmetic to use. > > Notice that such constant is used in a context that expects an > expression of type u64 (64 bits, unsigned) and the following > expression is currently being evaluated using 32-bit arithmetic: > > mode->clock * 1000 > > Addresses-Coverity-ID: 1466139 ("Unintentional integer overflow") > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> This is silly. The clock won't be over 4ghz -- we haven't seen anything over 1024x768 on this hardware as far as I know. The u64 is for the multiplication by width/height below. I've still applied the patch to shut up the tool.
Hi Eric, On 07/17/2018 01:40 PM, Eric Anholt wrote: > "Gustavo A. R. Silva" <gustavo@embeddedor.com> writes: > >> Add suffix ULL to constant 1000 in order to give the compiler complete >> information about the proper arithmetic to use. >> >> Notice that such constant is used in a context that expects an >> expression of type u64 (64 bits, unsigned) and the following >> expression is currently being evaluated using 32-bit arithmetic: >> >> mode->clock * 1000 >> >> Addresses-Coverity-ID: 1466139 ("Unintentional integer overflow") >> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > > This is silly. The clock won't be over 4ghz -- we haven't seen anything > over 1024x768 on this hardware as far as I know. The u64 is for the > multiplication by width/height below. > Yep. I understand. That's why I didn't use the word *fix* anywhere in the changelog. > I've still applied the patch to shut up the tool. > Thanks -- Gustavo
diff --git a/drivers/gpu/drm/pl111/pl111_display.c b/drivers/gpu/drm/pl111/pl111_display.c index a432eb7..754f6b2 100644 --- a/drivers/gpu/drm/pl111/pl111_display.c +++ b/drivers/gpu/drm/pl111/pl111_display.c @@ -63,7 +63,7 @@ pl111_mode_valid(struct drm_crtc *crtc, * We use the pixelclock to also account for interlaced modes, the * resulting bandwidth is in bytes per second. */ - bw = mode->clock * 1000; /* In Hz */ + bw = mode->clock * 1000ULL; /* In Hz */ bw = bw * mode->hdisplay * mode->vdisplay * cpp; bw = div_u64(bw, mode->htotal * mode->vtotal);
Add suffix ULL to constant 1000 in order to give the compiler complete information about the proper arithmetic to use. Notice that such constant is used in a context that expects an expression of type u64 (64 bits, unsigned) and the following expression is currently being evaluated using 32-bit arithmetic: mode->clock * 1000 Addresses-Coverity-ID: 1466139 ("Unintentional integer overflow") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- Changes in v2: - Use suffix ULL instead of UL. drivers/gpu/drm/pl111/pl111_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)