RDS: rewrite rds_ib_xmit
Now that the header always goes first, it is possible to
simplify rds_ib_xmit. Instead of having a path to handle 0-byte
dgrams and another path to handle >0, these can both be handled
in one path. This lets us eliminate xmit_populate_wr().
Rename sent to bytes_sent, to differentiate better from other
variable named "send".
Signed-off-by: Andy Grover <andy.grover@oracle.com>
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index 46026d9..06c1d7e 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -425,38 +425,6 @@
set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
}
-static inline void
-rds_ib_xmit_populate_wr(struct rds_ib_connection *ic,
- struct rds_ib_send_work *send, unsigned int pos,
- unsigned long buffer, unsigned int length,
- int send_flags)
-{
- struct ib_sge *sge;
-
- WARN_ON(pos != send - ic->i_sends);
-
- send->s_wr.send_flags = send_flags;
- send->s_wr.opcode = IB_WR_SEND;
- send->s_wr.num_sge = 1;
- send->s_wr.next = NULL;
- send->s_queued = jiffies;
- send->s_op = NULL;
-
- sge = &send->s_sge[0];
- sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header));
- sge->length = sizeof(struct rds_header);
- sge->lkey = ic->i_mr->lkey;
-
- if (length != 0) {
- send->s_wr.num_sge = 2;
-
- sge = &send->s_sge[1];
- sge->addr = buffer;
- sge->length = length;
- sge->lkey = ic->i_mr->lkey;
- }
-}
-
/*
* This can be called multiple times for a given message. The first time
* we see a message we map its scatterlist into the IB device so that
@@ -483,11 +451,11 @@
u32 pos;
u32 i;
u32 work_alloc;
- u32 credit_alloc;
+ u32 credit_alloc = 0;
u32 posted;
u32 adv_credits = 0;
int send_flags = 0;
- int sent;
+ int bytes_sent = 0;
int ret;
int flow_controlled = 0;
@@ -515,7 +483,6 @@
goto out;
}
- credit_alloc = work_alloc;
if (ic->i_flowctl) {
credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
adv_credits += posted;
@@ -591,13 +558,6 @@
BUG_ON(adv_credits > 255);
}
- send = &ic->i_sends[pos];
- first = send;
- prev = NULL;
- scat = &rm->data.m_sg[sg];
- sent = 0;
- i = 0;
-
/* Sometimes you want to put a fence between an RDMA
* READ and the following SEND.
* We could either do this all the time
@@ -607,31 +567,45 @@
if (rm->rdma.m_rdma_op.r_active && rm->rdma.m_rdma_op.r_fence)
send_flags = IB_SEND_FENCE;
- /*
- * We could be copying the header into the unused tail of the page.
- * That would need to be changed in the future when those pages might
- * be mapped userspace pages or page cache pages. So instead we always
- * use a second sge and our long-lived ring of mapped headers. We send
- * the header after the data so that the data payload can be aligned on
- * the receiver.
- */
+ /* Each frag gets a header. Msgs may be 0 bytes */
+ send = &ic->i_sends[pos];
+ first = send;
+ prev = NULL;
+ scat = &rm->data.m_sg[sg];
+ i = 0;
+ do {
+ unsigned int len = 0;
- /* handle a 0-len message */
- if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) {
- rds_ib_xmit_populate_wr(ic, send, pos, 0, 0, send_flags);
- goto add_header;
- }
+ /* Set up the header */
+ send->s_wr.send_flags = send_flags;
+ send->s_wr.opcode = IB_WR_SEND;
+ send->s_wr.num_sge = 1;
+ send->s_wr.next = NULL;
+ send->s_queued = jiffies;
+ send->s_op = NULL;
- /* if there's data reference it with a chain of work reqs */
- for (; i < work_alloc && scat != &rm->data.m_sg[rm->data.m_count]; i++) {
- unsigned int len;
+ send->s_sge[0].addr = ic->i_send_hdrs_dma
+ + (pos * sizeof(struct rds_header));
+ send->s_sge[0].length = sizeof(struct rds_header);
- send = &ic->i_sends[pos];
+ memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
- len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
- rds_ib_xmit_populate_wr(ic, send, pos,
- ib_sg_dma_address(dev, scat) + off, len,
- send_flags);
+ /* Set up the data, if present */
+ if (i < work_alloc
+ && scat != &rm->data.m_sg[rm->data.m_count]) {
+ len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
+ send->s_wr.num_sge = 2;
+
+ send->s_sge[1].addr = ib_sg_dma_address(dev, scat) + off;
+ send->s_sge[1].length = len;
+
+ bytes_sent += len;
+ off += len;
+ if (off == ib_sg_dma_len(dev, scat)) {
+ scat++;
+ off = 0;
+ }
+ }
/*
* We want to delay signaling completions just enough to get
@@ -658,18 +632,6 @@
rdsdebug("send %p wr %p num_sge %u next %p\n", send,
&send->s_wr, send->s_wr.num_sge, send->s_wr.next);
- sent += len;
- off += len;
- if (off == ib_sg_dma_len(dev, scat)) {
- scat++;
- off = 0;
- }
-
-add_header:
- /* Tack on the header after the data. The header SGE should already
- * have been set up to point to the right header buffer. */
- memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
-
if (adv_credits) {
struct rds_header *hdr = &ic->i_send_hdrs[pos];
@@ -685,12 +647,16 @@
prev = send;
pos = (pos + 1) % ic->i_send_ring.w_nr;
- }
+ send = &ic->i_sends[pos];
+ i++;
+
+ } while (i < work_alloc
+ && scat != &rm->data.m_sg[rm->data.m_count]);
/* Account the RDS header in the number of bytes we sent, but just once.
* The caller has no concept of fragmentation. */
if (hdr_off == 0)
- sent += sizeof(struct rds_header);
+ bytes_sent += sizeof(struct rds_header);
/* if we finished the message then send completion owns it */
if (scat == &rm->data.m_sg[rm->data.m_count]) {
@@ -699,6 +665,7 @@
ic->i_rm = NULL;
}
+ /* Put back wrs & credits we didn't use */
if (i < work_alloc) {
rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
work_alloc = i;
@@ -725,7 +692,7 @@
goto out;
}
- ret = sent;
+ ret = bytes_sent;
out:
BUG_ON(adv_credits);
return ret;