| Message ID | 20180706133646.312427-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
| Series | [net-next] stmmac: fix signed 64-bit division | expand |
From: Arnd Bergmann <arnd@arndb.de> Date: Fri, 6 Jul 2018 15:36:07 +0200 > 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. > > 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> Applied, thank you.
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,
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. 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> --- drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) -- 2.9.0