[PATCH, net-next] i40e: avoid 64-bit division where possible

Arnd Bergmann
2017-10-17T10:24:12Z

The new bandwidth calculation causes a link error on 32-bit
architectures, like

ERROR: "__aeabi_uldivmod" [drivers/net/ethernet/intel/i40e/i40e.ko] undefined!

The problem is the max_tx_rate calculation that uses 64-bit integers.
This is not really necessary since the numbers are in MBit/s so
they won't be higher than 40000 for the highest support rate, and
are guaranteed to not exceed 2^32 in future generations either.

This changes the representation to 'u32' when dealing with MBit/s
and uses div_u64() to convert from u64 numbers in byte/s.

Fixes: 2027d4deacb1 ("i40e: Add support setting TC max bandwidth rates")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/net/ethernet/intel/i40e/i40e.h | 4 ++--
drivers/net/ethernet/intel/i40e/i40e_main.c | 27 ++++++++++++++-------------
2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 266e1dc5e786..45155ef15d24 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -359,7 +359,7 @@ struct i40e_channel {
u8 enabled_tc;
struct i40e_aqc_vsi_properties_data info;

- u64 max_tx_rate;
+ u32 max_tx_rate; /* in Mbits/s */

/* track this channel belongs to which VSI */
struct i40e_vsi *parent_vsi;
@@ -1045,5 +1045,5 @@ static inline bool i40e_enabled_xdp_vsi(struct i40e_vsi *vsi)
}

int i40e_create_queue_channel(struct i40e_vsi *vsi, struct i40e_channel *ch);
-int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate);
+int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u32 max_tx_rate);
#endif /* _I40E_H_ */
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 624a2bc8a1df..e71fece72506 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -5439,7 +5439,7 @@ int i40e_get_link_speed(struct i40e_vsi *vsi)
*
* Helper function to set BW limit for a given VSI
**/
-int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate)
+int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u32 max_tx_rate)
{
struct i40e_pf *pf = vsi->back;
int speed = 0;
@@ -5448,7 +5448,7 @@ int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate)
speed = i40e_get_link_speed(vsi);
if (max_tx_rate > speed) {
dev_err(&pf->pdev->dev,
- "Invalid max tx rate %llu specified for VSI seid %d.",
+ "Invalid max tx rate %u specified for VSI seid %d.",
max_tx_rate, seid);
return -EINVAL;
}
@@ -5464,7 +5464,7 @@ int i40e_set_bw_limit(struct i40e_vsi *vsi, u16 seid, u64 max_tx_rate)
I40E_MAX_BW_INACTIVE_ACCUM, NULL);
if (ret)
dev_err(&pf->pdev->dev,
- "Failed set tx rate (%llu Mbps) for vsi->seid %u, err %s aq_err %s\n",
+ "Failed set tx rate (%u Mbps) for vsi->seid %u, err %s aq_err %s\n",
max_tx_rate, seid, i40e_stat_str(&pf->hw, ret),
i40e_aq_str(&pf->hw, pf->hw.aq.asq_last_status));
return ret;
@@ -6067,7 +6067,7 @@ int i40e_create_queue_channel(struct i40e_vsi *vsi,
return -EINVAL;

dev_dbg(&pf->pdev->dev,
- "Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+ "Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
ch->max_tx_rate,
ch->max_tx_rate / I40E_BW_CREDIT_DIVISOR, ch->seid);
}
@@ -6110,8 +6110,8 @@ static int i40e_configure_queue_channels(struct i40e_vsi *vsi)
/* Bandwidth limit through tc interface is in bytes/s,
* change to Mbit/s
*/
- ch->max_tx_rate =
- vsi->mqprio_qopt.max_rate[i] / (1000000 / 8);
+ ch->max_tx_rate = div_u64(vsi->mqprio_qopt.max_rate[i],
+ 1000000 / 8);

list_add_tail(&ch->list, &vsi->ch_list);

@@ -6554,7 +6554,7 @@ static int i40e_validate_mqprio_qopt(struct i40e_vsi *vsi,
"Invalid min tx rate (greater than 0) specified\n");
return -EINVAL;
}
- sum_max_rate += (mqprio_qopt->max_rate[i] / (1000000 / 8));
+ sum_max_rate += div_u64(mqprio_qopt->max_rate[i], 1000000 / 8);

if (i >= mqprio_qopt->qopt.num_tc - 1)
break;
@@ -6698,12 +6698,12 @@ static int i40e_setup_tc(struct net_device *netdev, void *type_data)

if (pf->flags & I40E_FLAG_TC_MQPRIO) {
if (vsi->mqprio_qopt.max_rate[0]) {
- u64 max_tx_rate = vsi->mqprio_qopt.max_rate[0] /
- (1000000 / 8);
+ u32 max_tx_rate = div_u64(vsi->mqprio_qopt.max_rate[0],
+ 1000000 / 8);
ret = i40e_set_bw_limit(vsi, vsi->seid, max_tx_rate);
if (!ret) {
dev_dbg(&vsi->back->pdev->dev,
- "Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+ "Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
max_tx_rate,
max_tx_rate / I40E_BW_CREDIT_DIVISOR,
vsi->seid);
@@ -8171,7 +8171,7 @@ static int i40e_rebuild_channels(struct i40e_vsi *vsi)
return -EINVAL;

dev_dbg(&vsi->back->pdev->dev,
- "Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+ "Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
ch->max_tx_rate,
ch->max_tx_rate / I40E_BW_CREDIT_DIVISOR,
ch->seid);
@@ -8446,12 +8446,13 @@ static void i40e_rebuild(struct i40e_pf *pf, bool reinit, bool lock_acquired)
}

if (vsi->mqprio_qopt.max_rate[0]) {
- u64 max_tx_rate = vsi->mqprio_qopt.max_rate[0] / (1000000 / 8);
+ u32 max_tx_rate = div_u64(vsi->mqprio_qopt.max_rate[0],
+ 1000000 / 8);

ret = i40e_set_bw_limit(vsi, vsi->seid, max_tx_rate);
if (!ret)
dev_dbg(&vsi->back->pdev->dev,
- "Set tx rate of %llu Mbps (count of 50Mbps %llu) for vsi->seid %u\n",
+ "Set tx rate of %u Mbps (count of 50Mbps %u) for vsi->seid %u\n",
max_tx_rate,
max_tx_rate / I40E_BW_CREDIT_DIVISOR,
vsi->seid);
--
2.9.0