i40e: Detection and recovery of TX queue hung logic moved to service_task from tx_timeout

This patch contains following changes:
   - detection and recovery logic (issue SW interrupt) has been moved to
     service_task from timeout function.
   - added some more debug info from tx_timeout.

Logic to detect and recover TX queue hung is now two step process:
  - service_task detects TX queue hung and sets a bit(hung_detected) if
    it was not set.
  - if bit was set (means this is back-back hung condition detected),
    issue SW interrupt and clear the bit.
  - napi_poll clears the bit unconditionally since it cleans TX/RX queues.

Change-ID: Ieed03a48927c845a988b3ff375090bf37caeb903
Signed-off-by: Kiran Patil <kiran.patil@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 0b9537b374127407e46f219c82bf59c84097ba17..dde7ae71bfb83414efed92f8d1aad76c32308dc9 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -579,6 +579,9 @@ struct i40e_q_vector {
 
        u8 num_ringpairs;       /* total number of ring pairs in vector */
 
+#define I40E_Q_VECTOR_HUNG_DETECT 0 /* Bit Index for hung detection logic */
+       unsigned long hung_detected; /* Set/Reset for hung_detection logic */
+
        cpumask_t affinity_mask;
        struct rcu_head rcu;    /* to avoid race with update stats on free */
        char name[I40E_INT_NAME_STR_LEN];

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 9e6268b4295a8e1fe8a85c438afa7f9718451c40..e19a5790a3c78ace3c4f6edf2276794efac0af85 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -4368,17 +4368,41 @@ static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi)
        else
                val = rd32(&pf->hw, I40E_PFINT_DYN_CTL0);
 
+       /* Bail out if interrupts are disabled because napi_poll
+        * execution in-progress or will get scheduled soon.
+        * napi_poll cleans TX and RX queues and updates 'next_to_clean'.
+        */
+       if (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK))
+               return;
+
        head = i40e_get_head(tx_ring);
 
        tx_pending = i40e_get_tx_pending(tx_ring);
 
-       /* Interrupts are disabled and TX pending is non-zero,
-        * trigger the SW interrupt (don't wait). Worst case
-        * there will be one extra interrupt which may result
-        * into not cleaning any queues because queues are cleaned.
+       /* HW is done executing descriptors, updated HEAD write back,
+        * but SW hasn't processed those descriptors. If interrupt is
+        * not generated from this point ON, it could result into
+        * dev_watchdog detecting timeout on those netdev_queue,
+        * hence proactively trigger SW interrupt.
         */
-       if (tx_pending && (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK)))
-               i40e_force_wb(vsi, tx_ring->q_vector);
+       if (tx_pending) {
+               /* NAPI Poll didn't run and clear since it was set */
+               if (test_and_clear_bit(I40E_Q_VECTOR_HUNG_DETECT,
+                                      &tx_ring->q_vector->hung_detected)) {
+                       netdev_info(vsi->netdev, "VSI_seid %d, Hung TX queue %d, tx_pending: %d, NTC:0x%x, HWB: 0x%x, NTU: 0x%x, TAIL: 0x%x\n",
+                                   vsi->seid, q_idx, tx_pending,
+                                   tx_ring->next_to_clean, head,
+                                   tx_ring->next_to_use,
+                                   readl(tx_ring->tail));
+                       netdev_info(vsi->netdev, "VSI_seid %d, Issuing force_wb for TX queue %d, Interrupt Reg: 0x%x\n",
+                                   vsi->seid, q_idx, val);
+                       i40e_force_wb(vsi, tx_ring->q_vector);
+               } else {
+                       /* First Chance - detected possible hung */
+                       set_bit(I40E_Q_VECTOR_HUNG_DETECT,
+                               &tx_ring->q_vector->hung_detected);
+               }
+       }
 }
 
 /**

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 7371df7b6fb0ce6495878052f0a6f2c49ca1c7a1..1d7d01c723b9f97d91961c20a1906e81d7e768ff 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -1891,6 +1891,8 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)
                return 0;
        }
 
+       /* Clear hung_detected bit */
+       clear_bit(I40E_Q_VECTOR_HUNG_DETECT, &q_vector->hung_detected);
        /* Since the actual Tx work is minimal, we can give the Tx a larger
         * budget and be more aggressive about cleaning up the Tx descriptors.
         */

diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
index 11561b648417a0da159e7f0bc5422e0a7735b19f..06b6636552ddf490c058edd4515d52aa99f02635 100644 (file)
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -127,17 +127,24 @@ void i40evf_free_tx_resources(struct i40e_ring *tx_ring)
 }
 
 /**
- * i40e_get_head - Retrieve head from head writeback
- * @tx_ring:  tx ring to fetch head of
+ * i40evf_get_tx_pending - how many Tx descriptors not processed
+ * @tx_ring: the ring of descriptors
  *
- * Returns value of Tx ring head based on value stored
- * in head write-back location
+ * Since there is no access to the ring head register
+ * in XL710, we need to use our local copies
  **/
-static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
+u32 i40evf_get_tx_pending(struct i40e_ring *ring)
 {
-       void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
+       u32 head, tail;
 
-       return le32_to_cpu(*(volatile __le32 *)head);
+       head = i40e_get_head(ring);
+       tail = readl(ring->tail);
+
+       if (head != tail)
+               return (head < tail) ?
+                       tail - head : (tail + ring->count - head);
+
+       return 0;
 }
 
 #define WB_STRIDE 0x3

diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h
index 929ddd9f8215c5bd613c2109aaf1b2458fcd1a01..e29bb3e86cfdc86378c5e924e6ed531f68979250 100644 (file)
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h
@@ -324,4 +324,19 @@ int i40evf_setup_rx_descriptors(struct i40e_ring *rx_ring);
 void i40evf_free_tx_resources(struct i40e_ring *tx_ring);
 void i40evf_free_rx_resources(struct i40e_ring *rx_ring);
 int i40evf_napi_poll(struct napi_struct *napi, int budget);
+u32 i40evf_get_tx_pending(struct i40e_ring *ring);
+
+/**
+ * i40e_get_head - Retrieve head from head writeback
+ * @tx_ring: Tx ring to fetch head of
+ *
+ * Returns value of Tx ring head based on value stored
+ * in head write-back location
+ **/
+static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
+{
+       void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
+
+       return le32_to_cpu(*(volatile __le32 *)head);
+}
 #endif /* _I40E_TXRX_H_ */