[net-next 5/9] i40e: avoid permanent lock of *_PTP_TX_IN_PROGRESS

[Jeff Kirsher]

From: Jacob Keller <jacob.e.kel...@intel.com>

The i40e driver uses a bit lock to indicate when a Tx timestamp is in
progress to avoid attempting to timestamp multiple packets at once. This
is required because hardware only has registers to handle one request at
a time.

There is a corner case where we failed to cleanup the bit lock after
a failed transmit. This can potentially result in a state bit being
locked forever.

Add some cleanup code to i40e_xmit_frame_ring to check and make sure we
cleanup incase of these failures. We also modify i40e_tx_map to return
an error code indication DMA failure.

Reported-by: Reported-by: David Mirabito <dav...@metamako.com>
Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirs...@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_txrx.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c 
b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 29321a6167a6..19984be0f70c 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2932,10 +2932,12 @@ bool __i40e_chk_linearize(struct sk_buff *skb)
  * @hdr_len:  size of the packet header
  * @td_cmd:   the command field in the descriptor
  * @td_offset: offset for checksum or crc
+ *
+ * Returns 0 on success, -1 on failure to DMA
  **/
-static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
-                              struct i40e_tx_buffer *first, u32 tx_flags,
-                              const u8 hdr_len, u32 td_cmd, u32 td_offset)
+static inline int i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
+                             struct i40e_tx_buffer *first, u32 tx_flags,
+                             const u8 hdr_len, u32 td_cmd, u32 td_offset)
 {
        unsigned int data_len = skb->data_len;
        unsigned int size = skb_headlen(skb);
@@ -3093,7 +3095,7 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, 
struct sk_buff *skb,
                mmiowb();
        }
 
-       return;
+       return 0;
 
 dma_error:
        dev_info(tx_ring->dev, "TX DMA map failed\n");
@@ -3110,6 +3112,8 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, 
struct sk_buff *skb,
        }
 
        tx_ring->next_to_use = i;
+
+       return -1;
 }
 
 /**
@@ -3210,8 +3214,9 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff 
*skb,
         */
        i40e_atr(tx_ring, skb, tx_flags);
 
-       i40e_tx_map(tx_ring, skb, first, tx_flags, hdr_len,
-                   td_cmd, td_offset);
+       if (i40e_tx_map(tx_ring, skb, first, tx_flags, hdr_len,
+                       td_cmd, td_offset))
+               goto cleanup_tx_tstamp;
 
        return NETDEV_TX_OK;
 
@@ -3219,6 +3224,15 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff 
*skb,
        i40e_trace(xmit_frame_ring_drop, first->skb, tx_ring);
        dev_kfree_skb_any(first->skb);
        first->skb = NULL;
+cleanup_tx_tstamp:
+       if (unlikely(tx_flags & I40E_TX_FLAGS_TSYN)) {
+               struct i40e_pf *pf = i40e_netdev_to_pf(tx_ring->netdev);
+
+               dev_kfree_skb_any(pf->ptp_tx_skb);
+               pf->ptp_tx_skb = NULL;
+               clear_bit_unlock(__I40E_PTP_TX_IN_PROGRESS, pf->state);
+       }
+
        return NETDEV_TX_OK;
 }
 
-- 
2.12.2