From e757e3e198795bfc56a28b41c494bcb27c0ee2ab Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Thu, 31 Jan 2013 07:43:22 +0000 Subject: [PATCH] ixgbevf: Make next_to_watch a pointer and adjust memory barriers to avoid races This change is meant to address several race issues that become possible because next_to_watch could possibly be set to a value that shows that the descriptor is done when it is not. In order to correct that we instead make next_to_watch a pointer that is set to NULL during cleanup, and set to the eop_desc after the descriptor rings have been written. To enforce proper ordering the next_to_watch pointer is not set until after a wmb writing the values to the last descriptor in a transmit. In order to guarantee that the descriptor is not read until after the eop_desc we use the read_barrier_depends which is only really necessary on the alpha architecture. Signed-off-by: Alexander Duyck Acked-by: Greg Rose Tested-by: Sibai Li Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/ixgbevf/ixgbevf.h | 2 +- drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 71 +++++++++++++---------- 2 files changed, 40 insertions(+), 33 deletions(-) diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h index fc0af9a..fff0d98 100644 --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h @@ -44,8 +44,8 @@ struct ixgbevf_tx_buffer { struct sk_buff *skb; dma_addr_t dma; unsigned long time_stamp; + union ixgbe_adv_tx_desc *next_to_watch; u16 length; - u16 next_to_watch; u16 mapped_as_page; }; diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c index c3db6cd..20736eb 100644 --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c @@ -190,28 +190,37 @@ static bool ixgbevf_clean_tx_irq(struct ixgbevf_q_vector *q_vector, struct ixgbevf_adapter *adapter = q_vector->adapter; union ixgbe_adv_tx_desc *tx_desc, *eop_desc; struct ixgbevf_tx_buffer *tx_buffer_info; - unsigned int i, eop, count = 0; + unsigned int i, count = 0; unsigned int total_bytes = 0, total_packets = 0; if (test_bit(__IXGBEVF_DOWN, &adapter->state)) return true; i = tx_ring->next_to_clean; - eop = tx_ring->tx_buffer_info[i].next_to_watch; - eop_desc = IXGBEVF_TX_DESC(tx_ring, eop); + tx_buffer_info = &tx_ring->tx_buffer_info[i]; + eop_desc = tx_buffer_info->next_to_watch; - while ((eop_desc->wb.status & cpu_to_le32(IXGBE_TXD_STAT_DD)) && - (count < tx_ring->count)) { + do { bool cleaned = false; - rmb(); /* read buffer_info after eop_desc */ - /* eop could change between read and DD-check */ - if (unlikely(eop != tx_ring->tx_buffer_info[i].next_to_watch)) - goto cont_loop; + + /* if next_to_watch is not set then there is no work pending */ + if (!eop_desc) + break; + + /* prevent any other reads prior to eop_desc */ + read_barrier_depends(); + + /* if DD is not set pending work has not been completed */ + if (!(eop_desc->wb.status & cpu_to_le32(IXGBE_TXD_STAT_DD))) + break; + + /* clear next_to_watch to prevent false hangs */ + tx_buffer_info->next_to_watch = NULL; + for ( ; !cleaned; count++) { struct sk_buff *skb; tx_desc = IXGBEVF_TX_DESC(tx_ring, i); - tx_buffer_info = &tx_ring->tx_buffer_info[i]; - cleaned = (i == eop); + cleaned = (tx_desc == eop_desc); skb = tx_buffer_info->skb; if (cleaned && skb) { @@ -234,12 +243,12 @@ static bool ixgbevf_clean_tx_irq(struct ixgbevf_q_vector *q_vector, i++; if (i == tx_ring->count) i = 0; + + tx_buffer_info = &tx_ring->tx_buffer_info[i]; } -cont_loop: - eop = tx_ring->tx_buffer_info[i].next_to_watch; - eop_desc = IXGBEVF_TX_DESC(tx_ring, eop); - } + eop_desc = tx_buffer_info->next_to_watch; + } while (count < tx_ring->count); tx_ring->next_to_clean = i; @@ -2806,8 +2815,7 @@ static bool ixgbevf_tx_csum(struct ixgbevf_ring *tx_ring, } static int ixgbevf_tx_map(struct ixgbevf_ring *tx_ring, - struct sk_buff *skb, u32 tx_flags, - unsigned int first) + struct sk_buff *skb, u32 tx_flags) { struct ixgbevf_tx_buffer *tx_buffer_info; unsigned int len; @@ -2832,7 +2840,6 @@ static int ixgbevf_tx_map(struct ixgbevf_ring *tx_ring, size, DMA_TO_DEVICE); if (dma_mapping_error(tx_ring->dev, tx_buffer_info->dma)) goto dma_error; - tx_buffer_info->next_to_watch = i; len -= size; total -= size; @@ -2862,7 +2869,6 @@ static int ixgbevf_tx_map(struct ixgbevf_ring *tx_ring, tx_buffer_info->dma)) goto dma_error; tx_buffer_info->mapped_as_page = true; - tx_buffer_info->next_to_watch = i; len -= size; total -= size; @@ -2881,8 +2887,6 @@ static int ixgbevf_tx_map(struct ixgbevf_ring *tx_ring, else i = i - 1; tx_ring->tx_buffer_info[i].skb = skb; - tx_ring->tx_buffer_info[first].next_to_watch = i; - tx_ring->tx_buffer_info[first].time_stamp = jiffies; return count; @@ -2891,7 +2895,6 @@ dma_error: /* clear timestamp and dma mappings for failed tx_buffer_info map */ tx_buffer_info->dma = 0; - tx_buffer_info->next_to_watch = 0; count--; /* clear timestamp and dma mappings for remaining portion of packet */ @@ -2908,7 +2911,8 @@ dma_error: } static void ixgbevf_tx_queue(struct ixgbevf_ring *tx_ring, int tx_flags, - int count, u32 paylen, u8 hdr_len) + int count, unsigned int first, u32 paylen, + u8 hdr_len) { union ixgbe_adv_tx_desc *tx_desc = NULL; struct ixgbevf_tx_buffer *tx_buffer_info; @@ -2959,6 +2963,16 @@ static void ixgbevf_tx_queue(struct ixgbevf_ring *tx_ring, int tx_flags, tx_desc->read.cmd_type_len |= cpu_to_le32(txd_cmd); + tx_ring->tx_buffer_info[first].time_stamp = jiffies; + + /* Force memory writes to complete before letting h/w + * know there are new descriptors to fetch. (Only + * applicable for weak-ordered memory model archs, + * such as IA-64). + */ + wmb(); + + tx_ring->tx_buffer_info[first].next_to_watch = tx_desc; tx_ring->next_to_use = i; } @@ -3050,15 +3064,8 @@ static int ixgbevf_xmit_frame(struct sk_buff *skb, struct net_device *netdev) tx_flags |= IXGBE_TX_FLAGS_CSUM; ixgbevf_tx_queue(tx_ring, tx_flags, - ixgbevf_tx_map(tx_ring, skb, tx_flags, first), - skb->len, hdr_len); - /* - * Force memory writes to complete before letting h/w - * know there are new descriptors to fetch. (Only - * applicable for weak-ordered memory model archs, - * such as IA-64). - */ - wmb(); + ixgbevf_tx_map(tx_ring, skb, tx_flags), + first, skb->len, hdr_len); writel(tx_ring->next_to_use, adapter->hw.hw_addr + tx_ring->tail); -- 2.7.4