cxgb3 - sge page management

Streamline sge page management.
Fix dma mappings when buffers are recycled.

Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 212 insertions, 211 deletions

diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index a60ec4d4707c..a2cfd68ac757 100644
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -46,23 +46,16 @@
 
 #define SGE_RX_SM_BUF_SIZE 1536
 
-/*
- * If USE_RX_PAGE is defined, the small freelist populated with (partial)
- * pages instead of skbs. Pages are carved up into RX_PAGE_SIZE chunks (must
- * be a multiple of the host page size).
- */
-#define USE_RX_PAGE
-#define RX_PAGE_SIZE 2048
-
-/*
- * skb freelist packets are copied into a new skb (and the freelist one is 
- * reused) if their len is <= 
- */
 #define SGE_RX_COPY_THRES  256
+#define SGE_RX_PULL_LEN    128
 
 /*
- * Minimum number of freelist entries before we start dropping TUNNEL frames.
+ * Page chunk size for FL0 buffers if FL0 is to be populated with page chunks.
+ * It must be a divisor of PAGE_SIZE.  If set to 0 FL0 will use sk_buffs
+ * directly.
  */
+#define FL0_PG_CHUNK_SIZE  2048
+
 #define SGE_RX_DROP_THRES 16
 
 /*
@@ -100,12 +93,12 @@ struct tx_sw_desc {		/* SW state per Tx descriptor */
         struct sk_buff *skb;
 };
 
-struct rx_sw_desc {             /* SW state per Rx descriptor */
+struct rx_sw_desc {                /* SW state per Rx descriptor */
         union {
                 struct sk_buff *skb;
-                struct sge_fl_page page;
-        } t;
-         DECLARE_PCI_UNMAP_ADDR(dma_addr);
+                struct fl_pg_chunk pg_chunk;
+        };
+        DECLARE_PCI_UNMAP_ADDR(dma_addr);
 };
 
 struct rsp_desc {               /* response queue descriptor */
@@ -351,27 +344,26 @@ static void free_rx_bufs(struct pci_dev *pdev, struct sge_fl *q)
 
                 pci_unmap_single(pdev, pci_unmap_addr(d, dma_addr),
                                  q->buf_size, PCI_DMA_FROMDEVICE);
-
-                if (q->buf_size != RX_PAGE_SIZE) {
-                        kfree_skb(d->t.skb);
-                        d->t.skb = NULL;
+                if (q->use_pages) {
+                        put_page(d->pg_chunk.page);
+                        d->pg_chunk.page = NULL;
                 } else {
-                        if (d->t.page.frag.page)
-                                put_page(d->t.page.frag.page);
-                        d->t.page.frag.page = NULL;
+                        kfree_skb(d->skb);
+                        d->skb = NULL;
                 }
                 if (++cidx == q->size)
                         cidx = 0;
         }
 
-        if (q->page.frag.page)
-                put_page(q->page.frag.page);
-        q->page.frag.page = NULL;
+        if (q->pg_chunk.page) {
+                __free_page(q->pg_chunk.page);
+                q->pg_chunk.page = NULL;
+        }
 }
 
 /**
  *      add_one_rx_buf - add a packet buffer to a free-buffer list
- *      @va: va of the buffer to add
+ *      @va:  buffer start VA
  *      @len: the buffer length
  *      @d: the HW Rx descriptor to write
  *      @sd: the SW Rx descriptor to write
@@ -381,7 +373,7 @@ static void free_rx_bufs(struct pci_dev *pdev, struct sge_fl *q)
  *      Add a buffer of the given length to the supplied HW and SW Rx
  *      descriptors.
  */
-static inline void add_one_rx_buf(unsigned char *va, unsigned int len,
+static inline void add_one_rx_buf(void *va, unsigned int len,
                                   struct rx_desc *d, struct rx_sw_desc *sd,
                                   unsigned int gen, struct pci_dev *pdev)
 {
@@ -397,6 +389,27 @@ static inline void add_one_rx_buf(unsigned char *va, unsigned int len,
         d->gen2 = cpu_to_be32(V_FLD_GEN2(gen));
 }
 
+static int alloc_pg_chunk(struct sge_fl *q, struct rx_sw_desc *sd, gfp_t gfp)
+{
+        if (!q->pg_chunk.page) {
+                q->pg_chunk.page = alloc_page(gfp);
+                if (unlikely(!q->pg_chunk.page))
+                        return -ENOMEM;
+                q->pg_chunk.va = page_address(q->pg_chunk.page);
+                q->pg_chunk.offset = 0;
+        }
+        sd->pg_chunk = q->pg_chunk;
+
+        q->pg_chunk.offset += q->buf_size;
+        if (q->pg_chunk.offset == PAGE_SIZE)
+                q->pg_chunk.page = NULL;
+        else {
+                q->pg_chunk.va += q->buf_size;
+                get_page(q->pg_chunk.page);
+        }
+        return 0;
+}
+
 /**
  *      refill_fl - refill an SGE free-buffer list
  *      @adapter: the adapter
@@ -410,49 +423,29 @@ static inline void add_one_rx_buf(unsigned char *va, unsigned int len,
  */
 static void refill_fl(struct adapter *adap, struct sge_fl *q, int n, gfp_t gfp)
 {
+        void *buf_start;
         struct rx_sw_desc *sd = &q->sdesc[q->pidx];
         struct rx_desc *d = &q->desc[q->pidx];
-        struct sge_fl_page *p = &q->page;
 
         while (n--) {
-                unsigned char *va;
-
-                if (unlikely(q->buf_size != RX_PAGE_SIZE)) {
-                        struct sk_buff *skb = alloc_skb(q->buf_size, gfp);
-
-                        if (!skb) {
-                                q->alloc_failed++;
+                if (q->use_pages) {
+                        if (unlikely(alloc_pg_chunk(q, sd, gfp))) {
+nomem:                          q->alloc_failed++;
                                 break;
                         }
-                        va = skb->data;
-                        sd->t.skb = skb;
+                        buf_start = sd->pg_chunk.va;
                 } else {
-                        if (!p->frag.page) {
-                                p->frag.page = alloc_pages(gfp, 0);
-                                if (unlikely(!p->frag.page)) {
-                                        q->alloc_failed++;
-                                        break;
-                                } else {
-                                        p->frag.size = RX_PAGE_SIZE;
-                                        p->frag.page_offset = 0;
-                                        p->va = page_address(p->frag.page);
-                                }
-                        }
+                        struct sk_buff *skb = alloc_skb(q->buf_size, gfp);
 
-                        memcpy(&sd->t, p, sizeof(*p));
-                        va = p->va;
+                        if (!skb)
+                                goto nomem;
 
-                        p->frag.page_offset += RX_PAGE_SIZE;
-                        BUG_ON(p->frag.page_offset > PAGE_SIZE);
-                        p->va += RX_PAGE_SIZE;
-                        if (p->frag.page_offset == PAGE_SIZE)
-                                p->frag.page = NULL;
-                        else
-                                get_page(p->frag.page);
+                        sd->skb = skb;
+                        buf_start = skb->data;
                 }
 
-                add_one_rx_buf(va, q->buf_size, d, sd, q->gen, adap->pdev);
-
+                add_one_rx_buf(buf_start, q->buf_size, d, sd, q->gen,
+                               adap->pdev);
                 d++;
                 sd++;
                 if (++q->pidx == q->size) {
@@ -487,7 +480,7 @@ static void recycle_rx_buf(struct adapter *adap, struct sge_fl *q,
         struct rx_desc *from = &q->desc[idx];
         struct rx_desc *to = &q->desc[q->pidx];
 
-        memcpy(&q->sdesc[q->pidx], &q->sdesc[idx], sizeof(struct rx_sw_desc));
+        q->sdesc[q->pidx] = q->sdesc[idx];
         to->addr_lo = from->addr_lo;    /* already big endian */
         to->addr_hi = from->addr_hi;    /* likewise */
         wmb();
@@ -650,6 +643,132 @@ static inline unsigned int flits_to_desc(unsigned int n)
 }
 
 /**
+ *      get_packet - return the next ingress packet buffer from a free list
+ *      @adap: the adapter that received the packet
+ *      @fl: the SGE free list holding the packet
+ *      @len: the packet length including any SGE padding
+ *      @drop_thres: # of remaining buffers before we start dropping packets
+ *
+ *      Get the next packet from a free list and complete setup of the
+ *      sk_buff.  If the packet is small we make a copy and recycle the
+ *      original buffer, otherwise we use the original buffer itself.  If a
+ *      positive drop threshold is supplied packets are dropped and their
+ *      buffers recycled if (a) the number of remaining buffers is under the
+ *      threshold and the packet is too big to copy, or (b) the packet should
+ *      be copied but there is no memory for the copy.
+ */
+static struct sk_buff *get_packet(struct adapter *adap, struct sge_fl *fl,
+                                  unsigned int len, unsigned int drop_thres)
+{
+        struct sk_buff *skb = NULL;
+        struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
+
+        prefetch(sd->skb->data);
+        fl->credits--;
+
+        if (len <= SGE_RX_COPY_THRES) {
+                skb = alloc_skb(len, GFP_ATOMIC);
+                if (likely(skb != NULL)) {
+                        __skb_put(skb, len);
+                        pci_dma_sync_single_for_cpu(adap->pdev,
+                                            pci_unmap_addr(sd, dma_addr), len,
+                                            PCI_DMA_FROMDEVICE);
+                        memcpy(skb->data, sd->skb->data, len);
+                        pci_dma_sync_single_for_device(adap->pdev,
+                                            pci_unmap_addr(sd, dma_addr), len,
+                                            PCI_DMA_FROMDEVICE);
+                } else if (!drop_thres)
+                        goto use_orig_buf;
+recycle:
+                recycle_rx_buf(adap, fl, fl->cidx);
+                return skb;
+        }
+
+        if (unlikely(fl->credits < drop_thres))
+                goto recycle;
+
+use_orig_buf:
+        pci_unmap_single(adap->pdev, pci_unmap_addr(sd, dma_addr),
+                         fl->buf_size, PCI_DMA_FROMDEVICE);
+        skb = sd->skb;
+        skb_put(skb, len);
+        __refill_fl(adap, fl);
+        return skb;
+}
+
+/**
+ *      get_packet_pg - return the next ingress packet buffer from a free list
+ *      @adap: the adapter that received the packet
+ *      @fl: the SGE free list holding the packet
+ *      @len: the packet length including any SGE padding
+ *      @drop_thres: # of remaining buffers before we start dropping packets
+ *
+ *      Get the next packet from a free list populated with page chunks.
+ *      If the packet is small we make a copy and recycle the original buffer,
+ *      otherwise we attach the original buffer as a page fragment to a fresh
+ *      sk_buff.  If a positive drop threshold is supplied packets are dropped
+ *      and their buffers recycled if (a) the number of remaining buffers is
+ *      under the threshold and the packet is too big to copy, or (b) there's
+ *      no system memory.
+ *
+ *      Note: this function is similar to @get_packet but deals with Rx buffers
+ *      that are page chunks rather than sk_buffs.
+ */
+static struct sk_buff *get_packet_pg(struct adapter *adap, struct sge_fl *fl,
+                                     unsigned int len, unsigned int drop_thres)
+{
+        struct sk_buff *skb = NULL;
+        struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
+
+        if (len <= SGE_RX_COPY_THRES) {
+                skb = alloc_skb(len, GFP_ATOMIC);
+                if (likely(skb != NULL)) {
+                        __skb_put(skb, len);
+                        pci_dma_sync_single_for_cpu(adap->pdev,
+                                            pci_unmap_addr(sd, dma_addr), len,
+                                            PCI_DMA_FROMDEVICE);
+                        memcpy(skb->data, sd->pg_chunk.va, len);
+                        pci_dma_sync_single_for_device(adap->pdev,
+                                            pci_unmap_addr(sd, dma_addr), len,
+                                            PCI_DMA_FROMDEVICE);
+                } else if (!drop_thres)
+                        return NULL;
+recycle:
+                fl->credits--;
+                recycle_rx_buf(adap, fl, fl->cidx);
+                return skb;
+        }
+
+        if (unlikely(fl->credits <= drop_thres))
+                goto recycle;
+
+        skb = alloc_skb(SGE_RX_PULL_LEN, GFP_ATOMIC);
+        if (unlikely(!skb)) {
+                if (!drop_thres)
+                        return NULL;
+                goto recycle;
+        }
+
+        pci_unmap_single(adap->pdev, pci_unmap_addr(sd, dma_addr),
+                         fl->buf_size, PCI_DMA_FROMDEVICE);
+        __skb_put(skb, SGE_RX_PULL_LEN);
+        memcpy(skb->data, sd->pg_chunk.va, SGE_RX_PULL_LEN);
+        skb_fill_page_desc(skb, 0, sd->pg_chunk.page,
+                           sd->pg_chunk.offset + SGE_RX_PULL_LEN,
+                           len - SGE_RX_PULL_LEN);
+        skb->len = len;
+        skb->data_len = len - SGE_RX_PULL_LEN;
+        skb->truesize += skb->data_len;
+
+        fl->credits--;
+        /*
+         * We do not refill FLs here, we let the caller do it to overlap a
+         * prefetch.
+         */
+        return skb;
+}
+
+/**
  *      get_imm_packet - return the next ingress packet buffer from a response
  *      @resp: the response descriptor containing the packet data
  *
@@ -1715,85 +1834,6 @@ static void rx_eth(struct adapter *adap, struct sge_rspq *rq,
                 netif_rx(skb);
 }
 
-#define SKB_DATA_SIZE 128
-
-static void skb_data_init(struct sk_buff *skb, struct sge_fl_page *p,
-                          unsigned int len)
-{
-        skb->len = len;
-        if (len <= SKB_DATA_SIZE) {
-                skb_copy_to_linear_data(skb, p->va, len);
-                skb->tail += len;
-                put_page(p->frag.page);
-        } else {
-                skb_copy_to_linear_data(skb, p->va, SKB_DATA_SIZE);
-                skb_shinfo(skb)->frags[0].page = p->frag.page;
-                skb_shinfo(skb)->frags[0].page_offset =
-                    p->frag.page_offset + SKB_DATA_SIZE;
-                skb_shinfo(skb)->frags[0].size = len - SKB_DATA_SIZE;
-                skb_shinfo(skb)->nr_frags = 1;
-                skb->data_len = len - SKB_DATA_SIZE;
-                skb->tail += SKB_DATA_SIZE;
-                skb->truesize += skb->data_len;
-        }
-}
-
-/**
-*      get_packet - return the next ingress packet buffer from a free list
-*      @adap: the adapter that received the packet
-*      @fl: the SGE free list holding the packet
-*      @len: the packet length including any SGE padding
-*      @drop_thres: # of remaining buffers before we start dropping packets
-*
-*      Get the next packet from a free list and complete setup of the
-*      sk_buff.  If the packet is small we make a copy and recycle the
-*      original buffer, otherwise we use the original buffer itself.  If a
-*      positive drop threshold is supplied packets are dropped and their
-*      buffers recycled if (a) the number of remaining buffers is under the
-*      threshold and the packet is too big to copy, or (b) the packet should
-*      be copied but there is no memory for the copy.
-*/
-static struct sk_buff *get_packet(struct adapter *adap, struct sge_fl *fl,
-                                  unsigned int len, unsigned int drop_thres)
-{
-        struct sk_buff *skb = NULL;
-        struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
-
-        prefetch(sd->t.skb->data);
-
-        if (len <= SGE_RX_COPY_THRES) {
-                skb = alloc_skb(len, GFP_ATOMIC);
-                if (likely(skb != NULL)) {
-                        struct rx_desc *d = &fl->desc[fl->cidx];
-                        dma_addr_t mapping =
-                            (dma_addr_t)((u64) be32_to_cpu(d->addr_hi) << 32 |
-                                         be32_to_cpu(d->addr_lo));
-
-                        __skb_put(skb, len);
-                        pci_dma_sync_single_for_cpu(adap->pdev, mapping, len,
-                                                    PCI_DMA_FROMDEVICE);
-                        skb_copy_from_linear_data(sd->t.skb, skb->data, len);
-                        pci_dma_sync_single_for_device(adap->pdev, mapping, len,
-                                                       PCI_DMA_FROMDEVICE);
-                } else if (!drop_thres)
-                        goto use_orig_buf;
-recycle:
-                recycle_rx_buf(adap, fl, fl->cidx);
-                return skb;
-        }
-
-        if (unlikely(fl->credits < drop_thres))
-                goto recycle;
-
-use_orig_buf:
-        pci_unmap_single(adap->pdev, pci_unmap_addr(sd, dma_addr),
-                         fl->buf_size, PCI_DMA_FROMDEVICE);
-        skb = sd->t.skb;
-        skb_put(skb, len);
-        __refill_fl(adap, fl);
-        return skb;
-}
-
 /**
  *      handle_rsp_cntrl_info - handles control information in a response
  *      @qs: the queue set corresponding to the response
@@ -1935,7 +1975,7 @@ static int process_responses(struct adapter *adap, struct sge_qset *qs,
                 } else if (flags & F_RSPD_IMM_DATA_VALID) {
                         skb = get_imm_packet(r);
                         if (unlikely(!skb)) {
-                              no_mem:
+no_mem:
                                 q->next_holdoff = NOMEM_INTR_DELAY;
                                 q->nomem++;
                                 /* consume one credit since we tried */
@@ -1945,53 +1985,29 @@ static int process_responses(struct adapter *adap, struct sge_qset *qs,
                         q->imm_data++;
                         ethpad = 0;
                 } else if ((len = ntohl(r->len_cq)) != 0) {
-                        struct sge_fl *fl =
-                            (len & F_RSPD_FLQ) ? &qs->fl[1] : &qs->fl[0];
+                        struct sge_fl *fl;
 
-                        if (fl->buf_size == RX_PAGE_SIZE) {
-                                struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
-                                struct sge_fl_page *p = &sd->t.page;
-
-                                prefetch(p->va);
-                                prefetch(p->va + L1_CACHE_BYTES);
+                        fl = (len & F_RSPD_FLQ) ? &qs->fl[1] : &qs->fl[0];
+                        if (fl->use_pages) {
+                                void *addr = fl->sdesc[fl->cidx].pg_chunk.va;
 
+                                prefetch(addr);
+#if L1_CACHE_BYTES < 128
+                                prefetch(addr + L1_CACHE_BYTES);
+#endif
                                 __refill_fl(adap, fl);
 
-                                pci_unmap_single(adap->pdev,
-                                                 pci_unmap_addr(sd, dma_addr),
-                                                 fl->buf_size,
-                                                 PCI_DMA_FROMDEVICE);
-
-                                if (eth) {
-                                        if (unlikely(fl->credits <
-                                                     SGE_RX_DROP_THRES))
-                                                goto eth_recycle;
-
-                                        skb = alloc_skb(SKB_DATA_SIZE,
-                                                        GFP_ATOMIC);
-                                        if (unlikely(!skb)) {
-eth_recycle:
-                                                q->rx_drops++;
-                                                recycle_rx_buf(adap, fl,
-                                                               fl->cidx);
-                                                goto eth_done;
-                                        }
-                                } else {
-                                        skb = alloc_skb(SKB_DATA_SIZE,
-                                                        GFP_ATOMIC);
-                                        if (unlikely(!skb))
-                                                goto no_mem;
-                                }
-
-                                skb_data_init(skb, p, G_RSPD_LEN(len));
-eth_done:
-                                fl->credits--;
-                                q->eth_pkts++;
-                        } else {
-                                fl->credits--;
+                                skb = get_packet_pg(adap, fl, G_RSPD_LEN(len),
+                                                 eth ? SGE_RX_DROP_THRES : 0);
+                        } else
                                 skb = get_packet(adap, fl, G_RSPD_LEN(len),
                                                  eth ? SGE_RX_DROP_THRES : 0);
-                        }
+                        if (unlikely(!skb)) {
+                                if (!eth)
+                                        goto no_mem;
+                                q->rx_drops++;
+                        } else if (unlikely(r->rss_hdr.opcode == CPL_TRACE_PKT))
+                                __skb_pull(skb, 2);
 
                         if (++fl->cidx == fl->size)
                                 fl->cidx = 0;
@@ -2016,20 +2032,15 @@ eth_done:
                         q->credits = 0;
                 }
 
-                if (skb) {
-                        /* Preserve the RSS info in csum & priority */
-                        skb->csum = rss_hi;
-                        skb->priority = rss_lo;
-
+                if (likely(skb != NULL)) {
                         if (eth)
                                 rx_eth(adap, q, skb, ethpad);
                         else {
-                                if (unlikely(r->rss_hdr.opcode ==
-                                             CPL_TRACE_PKT))
-                                        __skb_pull(skb, ethpad);
-
-                                ngathered = rx_offload(&adap->tdev, q,
-                                                       skb, offload_skbs,
+                                /* Preserve the RSS info in csum & priority */
+                                skb->csum = rss_hi;
+                                skb->priority = rss_lo;
+                                ngathered = rx_offload(&adap->tdev, q, skb,
+                                                       offload_skbs,
                                                        ngathered);
                         }
                 }
@@ -2635,25 +2646,15 @@ int t3_sge_alloc_qset(struct adapter *adapter, unsigned int id, int nports,
         q->txq[TXQ_ETH].stop_thres = nports *
             flits_to_desc(sgl_len(MAX_SKB_FRAGS + 1) + 3);
 
-        if (!is_offload(adapter)) {
-#ifdef USE_RX_PAGE
-                q->fl[0].buf_size = RX_PAGE_SIZE;
+#if FL0_PG_CHUNK_SIZE > 0
+        q->fl[0].buf_size = FL0_PG_CHUNK_SIZE;
 #else
-                q->fl[0].buf_size = SGE_RX_SM_BUF_SIZE + 2 +
-                    sizeof(struct cpl_rx_pkt);
+        q->fl[0].buf_size = SGE_RX_SM_BUF_SIZE + sizeof(struct cpl_rx_data);
 #endif
-                q->fl[1].buf_size = MAX_FRAME_SIZE + 2 +
-                    sizeof(struct cpl_rx_pkt);
-        } else {
-#ifdef USE_RX_PAGE
-                q->fl[0].buf_size = RX_PAGE_SIZE;
-#else
-                q->fl[0].buf_size = SGE_RX_SM_BUF_SIZE +
-                    sizeof(struct cpl_rx_data);
-#endif
-                q->fl[1].buf_size = (16 * 1024) -
-                    SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
-        }
+        q->fl[0].use_pages = FL0_PG_CHUNK_SIZE > 0;
+        q->fl[1].buf_size = is_offload(adapter) ?
+                (16 * 1024) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) :
+                MAX_FRAME_SIZE + 2 + sizeof(struct cpl_rx_pkt);
 
         spin_lock(&adapter->sge.reg_lock);