cxgb3 - fix interaction with pktgen

Do not use skb->cb to stash unmap info,
save the info to the descriptor state.

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

diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index c15e43a8543b983f82b0517010979d5eb782bbf8..7b13d8a31e38c1bcc5af6fc0dadb9dd9e3632f76 100644 (file)
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -91,6 +91,10 @@ struct rx_desc {
 
 struct tx_sw_desc {            /* SW state per Tx descriptor */
        struct sk_buff *skb;
+       u8 eop;       /* set if last descriptor for packet */
+       u8 addr_idx;  /* buffer index of first SGL entry in descriptor */
+       u8 fragidx;   /* first page fragment associated with descriptor */
+       s8 sflit;     /* start flit of first SGL entry in descriptor */
 };
 
 struct rx_sw_desc {                /* SW state per Rx descriptor */
@@ -109,13 +113,6 @@ struct rsp_desc {          /* response queue descriptor */
        u8 intr_gen;
 };
 
-struct unmap_info {            /* packet unmapping info, overlays skb->cb */
-       int sflit;              /* start flit of first SGL entry in Tx descriptor */
-       u16 fragidx;            /* first page fragment in current Tx descriptor */
-       u16 addr_idx;           /* buffer index of first SGL entry in descriptor */
-       u32 len;                /* mapped length of skb main body */
-};
-
 /*
  * Holds unmapping information for Tx packets that need deferred unmapping.
  * This structure lives at skb->head and must be allocated by callers.
@@ -209,32 +206,36 @@ static inline int need_skb_unmap(void)
  *
  *     Unmap the main body of an sk_buff and its page fragments, if any.
  *     Because of the fairly complicated structure of our SGLs and the desire
- *     to conserve space for metadata, we keep the information necessary to
- *     unmap an sk_buff partly in the sk_buff itself (in its cb), and partly
- *     in the Tx descriptors (the physical addresses of the various data
- *     buffers).  The send functions initialize the state in skb->cb so we
- *     can unmap the buffers held in the first Tx descriptor here, and we
- *     have enough information at this point to update the state for the next
- *     Tx descriptor.
+ *     to conserve space for metadata, the information necessary to unmap an
+ *     sk_buff is spread across the sk_buff itself (buffer lengths), the HW Tx
+ *     descriptors (the physical addresses of the various data buffers), and
+ *     the SW descriptor state (assorted indices).  The send functions
+ *     initialize the indices for the first packet descriptor so we can unmap
+ *     the buffers held in the first Tx descriptor here, and we have enough
+ *     information at this point to set the state for the next Tx descriptor.
+ *
+ *     Note that it is possible to clean up the first descriptor of a packet
+ *     before the send routines have written the next descriptors, but this
+ *     race does not cause any problem.  We just end up writing the unmapping
+ *     info for the descriptor first.
  */
 static inline void unmap_skb(struct sk_buff *skb, struct sge_txq *q,
                             unsigned int cidx, struct pci_dev *pdev)
 {
        const struct sg_ent *sgp;
-       struct unmap_info *ui = (struct unmap_info *)skb->cb;
-       int nfrags, frag_idx, curflit, j = ui->addr_idx;
+       struct tx_sw_desc *d = &q->sdesc[cidx];
+       int nfrags, frag_idx, curflit, j = d->addr_idx;
 
-       sgp = (struct sg_ent *)&q->desc[cidx].flit[ui->sflit];
+       sgp = (struct sg_ent *)&q->desc[cidx].flit[d->sflit];
+       frag_idx = d->fragidx;
 
-       if (ui->len) {
-               pci_unmap_single(pdev, be64_to_cpu(sgp->addr[0]), ui->len,
-                                PCI_DMA_TODEVICE);
-               ui->len = 0;    /* so we know for next descriptor for this skb */
+       if (frag_idx == 0 && skb_headlen(skb)) {
+               pci_unmap_single(pdev, be64_to_cpu(sgp->addr[0]),
+                                skb_headlen(skb), PCI_DMA_TODEVICE);
                j = 1;
        }
 
-       frag_idx = ui->fragidx;
-       curflit = ui->sflit + 1 + j;
+       curflit = d->sflit + 1 + j;
        nfrags = skb_shinfo(skb)->nr_frags;
 
        while (frag_idx < nfrags && curflit < WR_FLITS) {
@@ -250,10 +251,11 @@ static inline void unmap_skb(struct sk_buff *skb, struct sge_txq *q,
                frag_idx++;
        }
 
-       if (frag_idx < nfrags) {        /* SGL continues into next Tx descriptor */
-               ui->fragidx = frag_idx;
-               ui->addr_idx = j;
-               ui->sflit = curflit - WR_FLITS - j;     /* sflit can be -1 */
+       if (frag_idx < nfrags) {   /* SGL continues into next Tx descriptor */
+               d = cidx + 1 == q->size ? q->sdesc : d + 1;
+               d->fragidx = frag_idx;
+               d->addr_idx = j;
+               d->sflit = curflit - WR_FLITS - j; /* sflit can be -1 */
        }
 }
 
@@ -281,7 +283,7 @@ static void free_tx_desc(struct adapter *adapter, struct sge_txq *q,
                if (d->skb) {   /* an SGL is present */
                        if (need_unmap)
                                unmap_skb(d->skb, q, cidx, pdev);
-                       if (d->skb->priority == cidx)
+                       if (d->eop)
                                kfree_skb(d->skb);
                }
                ++d;
@@ -912,15 +914,13 @@ static void write_wr_hdr_sgl(unsigned int ndesc, struct sk_buff *skb,
 
        sd->skb = skb;
        if (need_skb_unmap()) {
-               struct unmap_info *ui = (struct unmap_info *)skb->cb;
-
-               ui->fragidx = 0;
-               ui->addr_idx = 0;
-               ui->sflit = flits;
+               sd->fragidx = 0;
+               sd->addr_idx = 0;
+               sd->sflit = flits;
        }
 
        if (likely(ndesc == 1)) {
-               skb->priority = pidx;
+               sd->eop = 1;
                wrp->wr_hi = htonl(F_WR_SOP | F_WR_EOP | V_WR_DATATYPE(1) |
                                   V_WR_SGLSFLT(flits)) | wr_hi;
                wmb();
@@ -948,6 +948,7 @@ static void write_wr_hdr_sgl(unsigned int ndesc, struct sk_buff *skb,
 
                        fp += avail;
                        d++;
+                       sd->eop = 0;
                        sd++;
                        if (++pidx == q->size) {
                                pidx = 0;
@@ -966,7 +967,7 @@ static void write_wr_hdr_sgl(unsigned int ndesc, struct sk_buff *skb,
                        wr_gen2(d, gen);
                        flits = 1;
                }
-               skb->priority = pidx;
+               sd->eop = 1;
                wrp->wr_hi |= htonl(F_WR_EOP);
                wmb();
                wp->wr_lo = htonl(V_WR_LEN(WR_FLITS) | V_WR_GEN(ogen)) | wr_lo;
@@ -1051,8 +1052,6 @@ static void write_tx_pkt_wr(struct adapter *adap, struct sk_buff *skb,
 
        sgp = ndesc == 1 ? (struct sg_ent *)&d->flit[flits] : sgl;
        sgl_flits = make_sgl(skb, sgp, skb->data, skb_headlen(skb), adap->pdev);
-       if (need_skb_unmap())
-               ((struct unmap_info *)skb->cb)->len = skb_headlen(skb);
 
        write_wr_hdr_sgl(ndesc, skb, d, pidx, q, sgl, flits, sgl_flits, gen,
                         htonl(V_WR_OP(FW_WROPCODE_TUNNEL_TX_PKT) | compl),
@@ -1380,13 +1379,14 @@ static void deferred_unmap_destructor(struct sk_buff *skb)
        const dma_addr_t *p;
        const struct skb_shared_info *si;
        const struct deferred_unmap_info *dui;
-       const struct unmap_info *ui = (struct unmap_info *)skb->cb;
 
        dui = (struct deferred_unmap_info *)skb->head;
        p = dui->addr;
 
-       if (ui->len)
-               pci_unmap_single(dui->pdev, *p++, ui->len, PCI_DMA_TODEVICE);
+       if (skb->tail - skb->transport_header)
+               pci_unmap_single(dui->pdev, *p++,
+                                skb->tail - skb->transport_header,
+                                PCI_DMA_TODEVICE);
 
        si = skb_shinfo(skb);
        for (i = 0; i < si->nr_frags; i++)
@@ -1451,8 +1451,6 @@ static void write_ofld_wr(struct adapter *adap, struct sk_buff *skb,
        if (need_skb_unmap()) {
                setup_deferred_unmapping(skb, adap->pdev, sgp, sgl_flits);
                skb->destructor = deferred_unmap_destructor;
-               ((struct unmap_info *)skb->cb)->len = (skb->tail -
-                                                      skb->transport_header);
        }
 
        write_wr_hdr_sgl(ndesc, skb, d, pidx, q, sgl, flits, sgl_flits,