[PATCH v1 1/1] net/nbl: fix hardware stats interrupt nesting issue

[Dimon Zhao]

The timer interrupt handler periodically queries and updates
hw_stats via mailbox.
Since mailbox operations rely on interrupts for packet reception,
this causes interrupt nesting.
To resolve this, trigger a task from the interrupt handler and
start a dedicated thread to execute this task,
eliminating the nested interrupt scenario.

Fixes: c9726a719ca1 ("net/nbl: support dropped packets counter")
Cc: sta...@dpdk.org

Signed-off-by: Dimon Zhao <dimon.z...@nebula-matrix.com>
---
 drivers/net/nbl/nbl_dev/nbl_dev.c | 52 ++++++++++++++++++++++++++++++-
 drivers/net/nbl/nbl_dev/nbl_dev.h |  2 ++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/net/nbl/nbl_dev/nbl_dev.c 
b/drivers/net/nbl/nbl_dev/nbl_dev.c
index 8a56939aa7..f389fa62e4 100644
--- a/drivers/net/nbl/nbl_dev/nbl_dev.c
+++ b/drivers/net/nbl/nbl_dev/nbl_dev.c
@@ -168,11 +168,37 @@ static int nbl_dev_update_hw_stats(struct rte_eth_dev 
*eth_dev)
        return ret;
 }
 
+static uint32_t nbl_dev_thread_hw_stats_task(void *param)
+{
+       struct rte_eth_dev *eth_dev = (struct rte_eth_dev *)param;
+       struct nbl_adapter *adapter = ETH_DEV_TO_NBL_DEV_PF_PRIV(eth_dev);
+       struct nbl_dev_mgt *dev_mgt = NBL_ADAPTER_TO_DEV_MGT(adapter);
+       struct nbl_dev_net_mgt *net_dev = NBL_DEV_MGT_TO_NET_DEV(dev_mgt);
+       char unused[16];
+       ssize_t nr = 0;
+
+       while (true) {
+               nr = read(net_dev->fd[0], &unused, sizeof(unused));
+               if (nr <= 0)
+                       break;
+
+               nbl_dev_update_hw_stats(eth_dev);
+       }
+
+       return 0;
+}
+
 static void nbl_dev_update_hw_stats_handler(void *param)
 {
        struct rte_eth_dev *eth_dev = param;
+       struct nbl_adapter *adapter = ETH_DEV_TO_NBL_DEV_PF_PRIV(eth_dev);
+       struct nbl_dev_mgt *dev_mgt = NBL_ADAPTER_TO_DEV_MGT(adapter);
+       struct nbl_dev_net_mgt *net_dev = NBL_DEV_MGT_TO_NET_DEV(dev_mgt);
+       char notify_byte = 0;
+       ssize_t nw = 0;
 
-       nbl_dev_update_hw_stats(eth_dev);
+       nw = write(net_dev->fd[1], &notify_byte, 1);
+       RTE_SET_USED(nw);
 
        rte_eal_alarm_set(NBL_ALARM_INTERNAL, nbl_dev_update_hw_stats_handler, 
eth_dev);
 }
@@ -187,6 +213,19 @@ static int nbl_dev_hw_stats_start(struct rte_eth_dev 
*eth_dev)
        struct nbl_ustore_stats ustore_stats = {0};
        int ret;
 
+       ret = pipe(net_dev->fd);
+       if (ret) {
+               NBL_LOG(ERR, "hw_stats pipe failed, ret %d", ret);
+               return ret;
+       }
+
+       ret = rte_thread_create_internal_control(&net_dev->tid, 
"nbl_hw_stats_thread",
+                                                nbl_dev_thread_hw_stats_task, 
eth_dev);
+       if (ret) {
+               NBL_LOG(ERR, "create hw_stats thread failed, ret %d", ret);
+               return ret;
+       }
+
        if (!common->is_vf) {
                ret = 
disp_ops->get_ustore_total_pkt_drop_stats(NBL_DEV_MGT_TO_DISP_PRIV(dev_mgt),
                                                common->eth_id, &ustore_stats);
@@ -261,8 +300,19 @@ static void nbl_dev_txrx_stop(struct rte_eth_dev *eth_dev)
 
 static int nbl_dev_hw_stats_stop(struct rte_eth_dev *eth_dev)
 {
+       struct nbl_adapter *adapter = ETH_DEV_TO_NBL_DEV_PF_PRIV(eth_dev);
+       struct nbl_dev_mgt *dev_mgt = NBL_ADAPTER_TO_DEV_MGT(adapter);
+       struct nbl_dev_net_mgt *net_dev = NBL_DEV_MGT_TO_NET_DEV(dev_mgt);
+
        rte_eal_alarm_cancel(nbl_dev_update_hw_stats_handler, eth_dev);
 
+       /* closing pipe to cause hw_stats thread to exit */
+       close(net_dev->fd[0]);
+       close(net_dev->fd[1]);
+       net_dev->fd[0] = -1;
+       net_dev->fd[1] = -1;
+       rte_thread_join(net_dev->tid, NULL);
+
        return 0;
 }
 
diff --git a/drivers/net/nbl/nbl_dev/nbl_dev.h 
b/drivers/net/nbl/nbl_dev/nbl_dev.h
index 21d87a372d..bfe2b06deb 100644
--- a/drivers/net/nbl/nbl_dev/nbl_dev.h
+++ b/drivers/net/nbl/nbl_dev/nbl_dev.h
@@ -60,6 +60,8 @@ struct nbl_dev_net_mgt {
        u8 rsv:6;
        struct nbl_hw_stats hw_stats;
        bool hw_stats_inited;
+       rte_thread_t tid;
+       int fd[2];
 };
 
 struct nbl_dev_mgt {
-- 
2.34.1