diff mbox series

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

Message ID 20171017102351.492492-1-arnd@arndb.de
State New
Headers show
Series [net-next] i40e: avoid 64-bit division where possible | expand

Commit Message

Arnd Bergmann Oct. 17, 2017, 10:23 a.m. UTC 
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(-)

-- 
2.9.0

Comments

Jeff Kirsher Oct. 17, 2017, 3:14 p.m. UTC | #1 
On Tue, 2017-10-17 at 12:23 +0200, Arnd Bergmann wrote:
> 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(-)


Unfortunately your patch does not apply cleanly to my tree.  Arnd,
could you please rebase your patch based my next-queue tree (dev-queue
branch)?  I already have several i40e patches queued up and applied to
that branch.
Arnd Bergmann Oct. 17, 2017, 3:46 p.m. UTC | #2 
On Tue, Oct 17, 2017 at 5:14 PM, Jeff Kirsher
<jeffrey.t.kirsher@intel.com> wrote:
> On Tue, 2017-10-17 at 12:23 +0200, Arnd Bergmann wrote:

>> The new bandwidth calculation causes a link error on 32-bit

>> architectures, like

>>

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

>> undefined!


> Unfortunately your patch does not apply cleanly to my tree.  Arnd,

> could you please rebase your patch based my next-queue tree (dev-queue

> branch)?  I already have several i40e patches queued up and applied to

> that branch.


I see you already applied a fix from Alan Brady on that branch. I think
his version is sufficient to avoid the build problems, but mine is better.
I've rebased my patch now to revert parts of his fix. Please decide for
yourself whether you want to apply it on top, or are happy enough with
the existing version.

       Arnd
diff mbox series

Patch

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);