From: Alexander Duyck Date: Sat, 28 Sep 2013 06:00:22 +0000 (+0000) Subject: i40e: Do not directly increment Tx next_to_use X-Git-Tag: v3.13-rc1~105^2~194^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fc4ac67bc98f1d54ec0ef8bcddf54892ad78e1f9;p=kernel%2Fkernel-generic.git i40e: Do not directly increment Tx next_to_use Avoid directly incrementing next_to_use for multiple reasons. The main reason being that if we directly increment it then it can attain a state where it is equal to the ring count. Technically this is a state it should not be able to reach but the way this is written it now can. This patch pulls the value off into a register and then increments it and writes back either the value or 0 depending on if the value is equal to the ring count. Signed-off-by: Alexander Duyck Signed-off-by: Jesse Brandeburg Tested-by: Kavindya Deegala Signed-off-by: Jeff Kirsher --- diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index 3bc3efa..e8db4dc 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -73,11 +73,12 @@ int i40e_program_fdir_filter(struct i40e_fdir_data *fdir_data, goto dma_fail; /* grab the next descriptor */ - fdir_desc = I40E_TX_FDIRDESC(tx_ring, tx_ring->next_to_use); - tx_buf = &tx_ring->tx_bi[tx_ring->next_to_use]; - tx_ring->next_to_use++; - if (tx_ring->next_to_use == tx_ring->count) - tx_ring->next_to_use = 0; + i = tx_ring->next_to_use; + fdir_desc = I40E_TX_FDIRDESC(tx_ring, i); + tx_buf = &tx_ring->tx_bi[i]; + + i++; + tx_ring->next_to_use = (i < tx_ring->count) ? i : 0; fdir_desc->qindex_flex_ptype_vsi = cpu_to_le32((fdir_data->q_index << I40E_TXD_FLTR_QW0_QINDEX_SHIFT) @@ -134,11 +135,11 @@ int i40e_program_fdir_filter(struct i40e_fdir_data *fdir_data, fdir_desc->fd_id = cpu_to_le32(fdir_data->fd_id); /* Now program a dummy descriptor */ - tx_desc = I40E_TX_DESC(tx_ring, tx_ring->next_to_use); - tx_buf = &tx_ring->tx_bi[tx_ring->next_to_use]; - tx_ring->next_to_use++; - if (tx_ring->next_to_use == tx_ring->count) - tx_ring->next_to_use = 0; + i = tx_ring->next_to_use; + tx_desc = I40E_TX_DESC(tx_ring, i); + + i++; + tx_ring->next_to_use = (i < tx_ring->count) ? i : 0; tx_desc->buffer_addr = cpu_to_le64(dma); td_cmd = I40E_TX_DESC_CMD_EOP | @@ -148,9 +149,6 @@ int i40e_program_fdir_filter(struct i40e_fdir_data *fdir_data, tx_desc->cmd_type_offset_bsz = build_ctob(td_cmd, 0, I40E_FDIR_MAX_RAW_PACKET_LOOKUP, 0); - /* Mark the data descriptor to be watched */ - tx_buf->next_to_watch = tx_desc; - /* Force memory writes to complete before letting h/w * know there are new descriptors to fetch. (Only * applicable for weak-ordered memory model archs, @@ -158,6 +156,9 @@ int i40e_program_fdir_filter(struct i40e_fdir_data *fdir_data, */ wmb(); + /* Mark the data descriptor to be watched */ + tx_buf->next_to_watch = tx_desc; + writel(tx_ring->next_to_use, tx_ring->tail); return 0; @@ -1143,6 +1144,7 @@ static void i40e_atr(struct i40e_ring *tx_ring, struct sk_buff *skb, struct tcphdr *th; unsigned int hlen; u32 flex_ptype, dtype_cmd; + u16 i; /* make sure ATR is enabled */ if (!(pf->flags & I40E_FLAG_FDIR_ATR_ENABLED)) @@ -1182,10 +1184,11 @@ static void i40e_atr(struct i40e_ring *tx_ring, struct sk_buff *skb, tx_ring->atr_count = 0; /* grab the next descriptor */ - fdir_desc = I40E_TX_FDIRDESC(tx_ring, tx_ring->next_to_use); - tx_ring->next_to_use++; - if (tx_ring->next_to_use == tx_ring->count) - tx_ring->next_to_use = 0; + i = tx_ring->next_to_use; + fdir_desc = I40E_TX_FDIRDESC(tx_ring, i); + + i++; + tx_ring->next_to_use = (i < tx_ring->count) ? i : 0; flex_ptype = (tx_ring->queue_index << I40E_TXD_FLTR_QW0_QINDEX_SHIFT) & I40E_TXD_FLTR_QW0_QINDEX_MASK; @@ -1481,15 +1484,16 @@ static void i40e_create_tx_ctx(struct i40e_ring *tx_ring, const u32 cd_tunneling, const u32 cd_l2tag2) { struct i40e_tx_context_desc *context_desc; + int i = tx_ring->next_to_use; if (!cd_type_cmd_tso_mss && !cd_tunneling && !cd_l2tag2) return; /* grab the next descriptor */ - context_desc = I40E_TX_CTXTDESC(tx_ring, tx_ring->next_to_use); - tx_ring->next_to_use++; - if (tx_ring->next_to_use == tx_ring->count) - tx_ring->next_to_use = 0; + context_desc = I40E_TX_CTXTDESC(tx_ring, i); + + i++; + tx_ring->next_to_use = (i < tx_ring->count) ? i : 0; /* cpu_to_le32 and assign to struct fields */ context_desc->tunneling_params = cpu_to_le32(cd_tunneling);