Messages in this thread | | | Subject | Re: [PATCH net-next] stmmac: fix signed 64-bit division | From | "Gustavo A. R. Silva" <> | Date | Fri, 6 Jul 2018 08:58:21 -0500 |
| |
Hi Arnd,
On 07/06/2018 08:36 AM, Arnd Bergmann wrote: > I link error on 32-bit ARM points to yet another arithmetic bug: > > drivers/net/ethernet/stmicro/stmmac/stmmac_tc.o: In function `tc_setup_cbs': > stmmac_tc.c:(.text+0x148): undefined reference to `__aeabi_uldivmod' > stmmac_tc.c:(.text+0x1fc): undefined reference to `__aeabi_uldivmod' > stmmac_tc.c:(.text+0x308): undefined reference to `__aeabi_uldivmod' > stmmac_tc.c:(.text+0x320): undefined reference to `__aeabi_uldivmod' > stmmac_tc.c:(.text+0x33c): undefined reference to `__aeabi_uldivmod' > drivers/net/ethernet/stmicro/stmmac/stmmac_tc.o:stmmac_tc.c:(.text+0x3a4): more undefined references to `__aeabi_uldivmod' follow > > I observe that the last change to add the 'ul' prefix was incorrect, > as it did not turn the result of the multiplication into a 64-bit > expression on 32-bit architectures. Further, it seems that the > do_div() macro gets confused by the fact that we pass a signed > variable rather than unsigned into it. >
Thanks for this fix.
> This changes the code to instead use the div_s64() helper that is > meant for signed division, along with changing the constant suffix > to 'll' to actually make it a 64-bit argument everywhere, fixing > both of the issues I pointed out. > > I'm not completely convinced that this makes the code correct, but > I'm fairly sure that we have two problems less than before. > > Fixes: 1f705bc61aee ("net: stmmac: Add support for CBS QDISC") > Fixes: c18a9c096683 ("net: stmmac_tc: use 64-bit arithmetic instead of 32-bit") > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> --- > drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c > index 8fedc288d138..1a96dd9c1091 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c > @@ -321,18 +321,16 @@ static int tc_setup_cbs(struct stmmac_priv *priv, > speed_div = (priv->speed == SPEED_100) ? 100000 : 1000000; > > /* Final adjustments for HW */ > - value = qopt->idleslope * 1024UL * ptr; > - do_div(value, speed_div); > + value = div_s64(qopt->idleslope * 1024ll * ptr, speed_div); > priv->plat->tx_queues_cfg[queue].idle_slope = value & GENMASK(31, 0); > > - value = -qopt->sendslope * 1024UL * ptr; > - do_div(value, speed_div); > + value = div_s64(-qopt->sendslope * 1024ll * ptr, speed_div); > priv->plat->tx_queues_cfg[queue].send_slope = value & GENMASK(31, 0); > > - value = qopt->hicredit * 1024UL * 8; > + value = qopt->hicredit * 1024ll * 8; > priv->plat->tx_queues_cfg[queue].high_credit = value & GENMASK(31, 0); > > - value = qopt->locredit * 1024UL * 8; > + value = qopt->locredit * 1024ll * 8; > priv->plat->tx_queues_cfg[queue].low_credit = value & GENMASK(31, 0); > > ret = stmmac_config_cbs(priv, priv->hw, >
| |