Re: [PATCH net-next] liquidio: Allow RX descriptors to be consumed before disabling NAPI.

[David Miller]

From: Felix Manlunas 
Date: Wed, 14 Mar 2018 16:17:47 -0700

> From: Raghu Vatsavayi 
> 
> Signed-off-by: Raghu Vatsavayi 
> Acked-by: Derek Chickles 
> Signed-off-by: Felix Manlunas 

This must have a reasonable commit message added, and that commit
message must explain in detail what exactly is happening here.

But since I did read the patch I do not think that doing a looping
sleeping read is the way to fix this problem.

Instead, you should find some way to wait on the specific event that
needs to occur.

[PATCH net-next] liquidio: Allow RX descriptors to be consumed before disabling NAPI.

[Felix Manlunas]

From: Raghu Vatsavayi 

Signed-off-by: Raghu Vatsavayi 
Acked-by: Derek Chickles 
Signed-off-by: Felix Manlunas 
---
 drivers/net/ethernet/cavium/liquidio/lio_core.c| 23 
 drivers/net/ethernet/cavium/liquidio/lio_main.c| 25 +-
 drivers/net/ethernet/cavium/liquidio/lio_vf_main.c | 23 
 .../net/ethernet/cavium/liquidio/octeon_network.h  |  1 +
 4 files changed, 53 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_core.c 
b/drivers/net/ethernet/cavium/liquidio/lio_core.c
index e7b6eb8..8e4716a 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_core.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_core.c
@@ -1157,3 +1157,26 @@ int liquidio_change_mtu(struct net_device *netdev, int 
new_mtu)
octeon_free_soft_command(oct, sc);
return 0;
 }
+
+int lio_wait_for_clean_oq(struct octeon_device *oct)
+{
+   int retry = 100, pending_pkts = 0;
+   int idx;
+
+   do {
+   pending_pkts = 0;
+
+   for (idx = 0; idx < MAX_OCTEON_OUTPUT_QUEUES(oct); idx++) {
+   if (!(oct->io_qmask.oq & BIT_ULL(idx)))
+   continue;
+   pending_pkts +=
+   atomic_read(>droq[idx]->pkts_pending);
+   }
+
+   if (pending_pkts > 0)
+   schedule_timeout_uninterruptible(1);
+
+   } while (retry-- && pending_pkts);
+
+   return pending_pkts;
+}
diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c 
b/drivers/net/ethernet/cavium/liquidio/lio_main.c
index 140085b..345fe6e 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
@@ -2240,16 +2240,6 @@ static int liquidio_stop(struct net_device *netdev)
struct octeon_device *oct = lio->oct_dev;
struct napi_struct *napi, *n;
 
-   if (oct->props[lio->ifidx].napi_enabled) {
-   list_for_each_entry_safe(napi, n, >napi_list, dev_list)
-   napi_disable(napi);
-
-   oct->props[lio->ifidx].napi_enabled = 0;
-
-   if (OCTEON_CN23XX_PF(oct))
-   oct->droq[0]->ops.poll_mode = 0;
-   }
-
ifstate_reset(lio, LIO_IFSTATE_RUNNING);
 
netif_tx_disable(netdev);
@@ -2275,6 +2265,21 @@ static int liquidio_stop(struct net_device *netdev)
lio->ptp_clock = NULL;
}
 
+   /* Wait for any pending Rx descriptors */
+   if (lio_wait_for_clean_oq(oct))
+   netif_info(lio, rx_err, lio->netdev,
+  "Proceeding with stop interface after partial RX 
desc processing\n");
+
+   if (oct->props[lio->ifidx].napi_enabled == 1) {
+   list_for_each_entry_safe(napi, n, >napi_list, dev_list)
+   napi_disable(napi);
+
+   oct->props[lio->ifidx].napi_enabled = 0;
+
+   if (OCTEON_CN23XX_PF(oct))
+   oct->droq[0]->ops.poll_mode = 0;
+   }
+
dev_info(>pci_dev->dev, "%s interface is stopped\n", netdev->name);
 
return 0;
diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c 
b/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
index 3342d64..66655df 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
@@ -1281,15 +1281,6 @@ static int liquidio_stop(struct net_device *netdev)
/* tell Octeon to stop forwarding packets to host */
send_rx_ctrl_cmd(lio, 0);
 
-   if (oct->props[lio->ifidx].napi_enabled) {
-   list_for_each_entry_safe(napi, n, >napi_list, dev_list)
-   napi_disable(napi);
-
-   oct->props[lio->ifidx].napi_enabled = 0;
-
-   oct->droq[0]->ops.poll_mode = 0;
-   }
-
netif_info(lio, ifdown, lio->netdev, "Stopping interface!\n");
/* Inform that netif carrier is down */
lio->intf_open = 0;
@@ -1302,6 +1293,20 @@ static int liquidio_stop(struct net_device *netdev)
 
txqs_stop(netdev);
 
+   /* Wait for any pending Rx descriptors */
+   if (lio_wait_for_clean_oq(oct))
+   netif_info(lio, rx_err, lio->netdev,
+  "Proceeding with stop interface after partial RX 
desc processing\n");
+
+   if (oct->props[lio->ifidx].napi_enabled == 1) {
+   list_for_each_entry_safe(napi, n, >napi_list, dev_list)
+   napi_disable(napi);
+
+   oct->props[lio->ifidx].napi_enabled = 0;
+
+   oct->droq[0]->ops.poll_mode = 0;
+   }
+
dev_info(>pci_dev->dev, "%s interface is stopped\n", netdev->name);
 
return 0;
diff --git a/drivers/net/ethernet/cavium/liquidio/octeon_network.h