| Message ID | 1644395942-4186-1-git-send-email-wangqing@vivo.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: dsa: ocelot: use div64_u64() instead of do_div() | expand |
Hi Wang, On Wed, Feb 09, 2022 at 12:39:02AM -0800, Qing Wang wrote: > From: Wang Qing <wangqing@vivo.com> > > do_div() does a 64-by-32 division. > When the divisor is u64, do_div() truncates it to 32 bits, this means it > can test non-zero and be truncated to zero for division. > > fix do_div.cocci warning: > do_div() does a 64-by-32 division, please consider using div64_u64 instead. > > Signed-off-by: Wang Qing <wangqing@vivo.com> > --- > drivers/net/dsa/ocelot/felix_vsc9959.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c > index bf8d382..5c2482f > --- a/drivers/net/dsa/ocelot/felix_vsc9959.c > +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c > @@ -1178,7 +1178,7 @@ static void vsc9959_new_base_time(struct ocelot *ocelot, ktime_t base_time, > if (base_time < current_time) { > u64 nr_of_cycles = current_time - base_time; > > - do_div(nr_of_cycles, cycle_time); > + div64_u64(nr_of_cycles, cycle_time); > new_base_time += cycle_time * (nr_of_cycles + 1); > } > > -- > 2.7.4 > I would prefer that you teach your scripts that, if a range check exists for the divisor prior to the division, it gets taken into consideration. vsc9959_qos_port_tas_set: if (taprio->cycle_time > NSEC_PER_SEC || taprio->cycle_time_extension >= NSEC_PER_SEC) return -EINVAL; vsc9959_new_base_time(ocelot, taprio->base_time, taprio->cycle_time, &base_ts); vsc9959_psfp_sgi_set: if (sgi->cycletime < VSC9959_PSFP_GATE_CYCLETIME_MIN || sgi->cycletime > NSEC_PER_SEC) return -EINVAL; vsc9959_new_base_time(ocelot, sgi->basetime, sgi->cycletime, &base_ts); So all callers provide a cycle_time argument that is smaller than NSEC_PER_SEC (1000000000L = 0x3B9ACA00 => fits on 32 bits).
diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c index bf8d382..5c2482f --- a/drivers/net/dsa/ocelot/felix_vsc9959.c +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c @@ -1178,7 +1178,7 @@ static void vsc9959_new_base_time(struct ocelot *ocelot, ktime_t base_time, if (base_time < current_time) { u64 nr_of_cycles = current_time - base_time; - do_div(nr_of_cycles, cycle_time); + div64_u64(nr_of_cycles, cycle_time); new_base_time += cycle_time * (nr_of_cycles + 1); }