git: 80458e3874ea - stable/13 - cxgbei: Add support for zero-copy iSCSI target transmission/read.
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Date: Fri, 29 Oct 2021 23:58:08 UTC
The branch stable/13 has been updated by jhb:
URL: https://cgit.FreeBSD.org/src/commit/?id=80458e3874eaa92c704b2196fb2987deed55207e
commit 80458e3874eaa92c704b2196fb2987deed55207e
Author: John Baldwin <jhb@FreeBSD.org>
AuthorDate: 2021-05-14 19:17:20 +0000
Commit: John Baldwin <jhb@FreeBSD.org>
CommitDate: 2021-10-29 22:55:20 +0000
cxgbei: Add support for zero-copy iSCSI target transmission/read.
- Switch to allocating the cxgbei version of icl_pdu explicitly
as a separate refcounted object allocated via malloc/free
instead of storing it in the bhs mbuf prior to the bhs.
- Support the icl_conn_pdu_queue_cb() method to set a callback
on a PDU to be invoked when the PDU is freed.
- For ICL_NOCOPY buffers, use an external mbuf to manage the
storage for the buffer via m_extaddref(). Each external mbuf
holds a reference on the associated PDU, so the callback is
invoked once all of the external mbufs have been freed.
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D29910
(cherry picked from commit a1c687347a7f983dadec10949938ee4d1b321120)
---
sys/dev/cxgbe/cxgbei/cxgbei.h | 4 +
sys/dev/cxgbe/cxgbei/icl_cxgbei.c | 161 ++++++++++++++++++++++++++++++--------
2 files changed, 132 insertions(+), 33 deletions(-)
diff --git a/sys/dev/cxgbe/cxgbei/cxgbei.h b/sys/dev/cxgbe/cxgbei/cxgbei.h
index 3b17a4f2b36a..9941e817b9cb 100644
--- a/sys/dev/cxgbe/cxgbei/cxgbei.h
+++ b/sys/dev/cxgbe/cxgbei/cxgbei.h
@@ -96,6 +96,10 @@ struct icl_cxgbei_pdu {
uint32_t icp_signature;
uint32_t icp_seq; /* For debug only */
u_int icp_flags;
+
+ u_int ref_cnt;
+ icl_pdu_cb cb;
+ int error;
};
static inline struct icl_cxgbei_pdu *
diff --git a/sys/dev/cxgbe/cxgbei/icl_cxgbei.c b/sys/dev/cxgbe/cxgbei/icl_cxgbei.c
index f91b9ee38616..f661d0a9d7d7 100644
--- a/sys/dev/cxgbe/cxgbei/icl_cxgbei.c
+++ b/sys/dev/cxgbe/cxgbei/icl_cxgbei.c
@@ -100,6 +100,8 @@ __FBSDID("$FreeBSD$");
#include "tom/t4_tom.h"
#include "cxgbei.h"
+static MALLOC_DEFINE(M_CXGBEI, "cxgbei", "cxgbei(4)");
+
SYSCTL_NODE(_kern_icl, OID_AUTO, cxgbei, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
"Chelsio iSCSI offload");
static int coalesce = 1;
@@ -130,6 +132,7 @@ static icl_conn_pdu_data_segment_length_t
static icl_conn_pdu_append_data_t icl_cxgbei_conn_pdu_append_data;
static icl_conn_pdu_get_data_t icl_cxgbei_conn_pdu_get_data;
static icl_conn_pdu_queue_t icl_cxgbei_conn_pdu_queue;
+static icl_conn_pdu_queue_cb_t icl_cxgbei_conn_pdu_queue_cb;
static icl_conn_handoff_t icl_cxgbei_conn_handoff;
static icl_conn_free_t icl_cxgbei_conn_free;
static icl_conn_close_t icl_cxgbei_conn_close;
@@ -146,6 +149,7 @@ static kobj_method_t icl_cxgbei_methods[] = {
KOBJMETHOD(icl_conn_pdu_append_data, icl_cxgbei_conn_pdu_append_data),
KOBJMETHOD(icl_conn_pdu_get_data, icl_cxgbei_conn_pdu_get_data),
KOBJMETHOD(icl_conn_pdu_queue, icl_cxgbei_conn_pdu_queue),
+ KOBJMETHOD(icl_conn_pdu_queue_cb, icl_cxgbei_conn_pdu_queue_cb),
KOBJMETHOD(icl_conn_handoff, icl_cxgbei_conn_handoff),
KOBJMETHOD(icl_conn_free, icl_cxgbei_conn_free),
KOBJMETHOD(icl_conn_close, icl_cxgbei_conn_close),
@@ -161,54 +165,108 @@ DEFINE_CLASS(icl_cxgbei, icl_cxgbei_methods, sizeof(struct icl_cxgbei_conn));
void
icl_cxgbei_conn_pdu_free(struct icl_conn *ic, struct icl_pdu *ip)
{
-#ifdef INVARIANTS
struct icl_cxgbei_pdu *icp = ip_to_icp(ip);
-#endif
+ KASSERT(icp->ref_cnt != 0, ("freeing deleted PDU"));
MPASS(icp->icp_signature == CXGBEI_PDU_SIGNATURE);
MPASS(ic == ip->ip_conn);
- MPASS(ip->ip_bhs_mbuf != NULL);
m_freem(ip->ip_ahs_mbuf);
m_freem(ip->ip_data_mbuf);
- m_freem(ip->ip_bhs_mbuf); /* storage for icl_cxgbei_pdu itself */
+ m_freem(ip->ip_bhs_mbuf);
+
+ KASSERT(ic != NULL || icp->ref_cnt == 1,
+ ("orphaned PDU has oustanding references"));
+ if (atomic_fetchadd_int(&icp->ref_cnt, -1) != 1)
+ return;
+
+ free(icp, M_CXGBEI);
#ifdef DIAGNOSTIC
if (__predict_true(ic != NULL))
refcount_release(&ic->ic_outstanding_pdus);
#endif
}
+static void
+icl_cxgbei_pdu_call_cb(struct icl_pdu *ip)
+{
+ struct icl_cxgbei_pdu *icp = ip_to_icp(ip);
+
+ MPASS(icp->icp_signature == CXGBEI_PDU_SIGNATURE);
+
+ if (icp->cb != NULL)
+ icp->cb(ip, icp->error);
+#ifdef DIAGNOSTIC
+ if (__predict_true(ip->ip_conn != NULL))
+ refcount_release(&ip->ip_conn->ic_outstanding_pdus);
+#endif
+ free(icp, M_CXGBEI);
+}
+
+static void
+icl_cxgbei_pdu_done(struct icl_pdu *ip, int error)
+{
+ struct icl_cxgbei_pdu *icp = ip_to_icp(ip);
+
+ if (error != 0)
+ icp->error = error;
+
+ m_freem(ip->ip_ahs_mbuf);
+ ip->ip_ahs_mbuf = NULL;
+ m_freem(ip->ip_data_mbuf);
+ ip->ip_data_mbuf = NULL;
+ m_freem(ip->ip_bhs_mbuf);
+ ip->ip_bhs_mbuf = NULL;
+
+ /*
+ * All other references to this PDU should have been dropped
+ * by the m_freem() of ip_data_mbuf.
+ */
+ if (atomic_fetchadd_int(&icp->ref_cnt, -1) == 1)
+ icl_cxgbei_pdu_call_cb(ip);
+ else
+ __assert_unreachable();
+}
+
+static void
+icl_cxgbei_mbuf_done(struct mbuf *mb)
+{
+
+ struct icl_cxgbei_pdu *icp = (struct icl_cxgbei_pdu *)mb->m_ext.ext_arg1;
+
+ /*
+ * NB: mb_free_mext() might leave ref_cnt as 1 without
+ * decrementing it if it hits the fast path in the ref_cnt
+ * check.
+ */
+ icl_cxgbei_pdu_call_cb(&icp->ip);
+}
+
struct icl_pdu *
icl_cxgbei_new_pdu(int flags)
{
struct icl_cxgbei_pdu *icp;
struct icl_pdu *ip;
struct mbuf *m;
- uintptr_t a;
- m = m_gethdr(flags, MT_DATA);
- if (__predict_false(m == NULL))
+ icp = malloc(sizeof(*icp), M_CXGBEI, flags | M_ZERO);
+ if (__predict_false(icp == NULL))
return (NULL);
- a = roundup2(mtod(m, uintptr_t), _Alignof(struct icl_cxgbei_pdu));
- icp = (struct icl_cxgbei_pdu *)a;
- bzero(icp, sizeof(*icp));
-
icp->icp_signature = CXGBEI_PDU_SIGNATURE;
+ icp->ref_cnt = 1;
ip = &icp->ip;
- ip->ip_bhs_mbuf = m;
- a = roundup2((uintptr_t)(icp + 1), _Alignof(struct iscsi_bhs *));
- ip->ip_bhs = (struct iscsi_bhs *)a;
-#ifdef INVARIANTS
- /* Everything must fit entirely in the mbuf. */
- a = (uintptr_t)(ip->ip_bhs + 1);
- MPASS(a <= (uintptr_t)m + MSIZE);
-#endif
- bzero(ip->ip_bhs, sizeof(*ip->ip_bhs));
+ m = m_gethdr(flags, MT_DATA);
+ if (__predict_false(m == NULL)) {
+ free(icp, M_CXGBEI);
+ return (NULL);
+ }
- m->m_data = (void *)ip->ip_bhs;
+ ip->ip_bhs_mbuf = m;
+ ip->ip_bhs = mtod(m, struct iscsi_bhs *);
+ memset(ip->ip_bhs, 0, sizeof(*ip->ip_bhs));
m->m_len = sizeof(struct iscsi_bhs);
m->m_pkthdr.len = m->m_len;
@@ -306,16 +364,22 @@ finalize_pdu(struct icl_cxgbei_conn *icc, struct icl_cxgbei_pdu *icp)
bhs->bhs_data_segment_len[1] = ip->ip_data_len >> 8;
bhs->bhs_data_segment_len[0] = ip->ip_data_len >> 16;
- /* "Convert" PDU to mbuf chain. Do not use icp/ip after this. */
- m->m_pkthdr.len = sizeof(struct iscsi_bhs) + ip->ip_data_len + padding;
+ /*
+ * Extract mbuf chain from PDU.
+ */
+ m->m_pkthdr.len += ip->ip_data_len + padding;
m->m_next = ip->ip_data_mbuf;
set_mbuf_ulp_submode(m, ulp_submode);
-#ifdef INVARIANTS
- bzero(icp, sizeof(*icp));
-#endif
-#ifdef DIAGNOSTIC
- refcount_release(&icc->ic.ic_outstanding_pdus);
-#endif
+ ip->ip_bhs_mbuf = NULL;
+ ip->ip_data_mbuf = NULL;
+ ip->ip_bhs = NULL;
+
+ /*
+ * Drop PDU reference on icp. Additional references might
+ * still be held by zero-copy PDU buffers (ICL_NOCOPY).
+ */
+ if (atomic_fetchadd_int(&icp->ref_cnt, -1) == 1)
+ icl_cxgbei_pdu_call_cb(ip);
return (m);
}
@@ -324,9 +388,7 @@ int
icl_cxgbei_conn_pdu_append_data(struct icl_conn *ic, struct icl_pdu *ip,
const void *addr, size_t len, int flags)
{
-#ifdef INVARIANTS
struct icl_cxgbei_pdu *icp = ip_to_icp(ip);
-#endif
struct mbuf *m, *m_tail;
const char *src;
@@ -339,6 +401,29 @@ icl_cxgbei_conn_pdu_append_data(struct icl_conn *ic, struct icl_pdu *ip,
for (; m_tail->m_next != NULL; m_tail = m_tail->m_next)
;
+ if (flags & ICL_NOCOPY) {
+ m = m_get(flags & ~ICL_NOCOPY, MT_DATA);
+ if (m == NULL) {
+ ICL_WARN("failed to allocate mbuf");
+ return (ENOMEM);
+ }
+
+ m->m_flags |= M_RDONLY;
+ m_extaddref(m, __DECONST(char *, addr), len, &icp->ref_cnt,
+ icl_cxgbei_mbuf_done, icp, NULL);
+ m->m_len = len;
+ if (ip->ip_data_mbuf == NULL) {
+ ip->ip_data_mbuf = m;
+ ip->ip_data_len = len;
+ } else {
+ m_tail->m_next = m;
+ m_tail = m_tail->m_next;
+ ip->ip_data_len += len;
+ }
+
+ return (0);
+ }
+
src = (const char *)addr;
/* Allocate as jumbo mbufs of size MJUM16BYTES. */
@@ -403,6 +488,13 @@ icl_cxgbei_conn_pdu_get_data(struct icl_conn *ic, struct icl_pdu *ip,
void
icl_cxgbei_conn_pdu_queue(struct icl_conn *ic, struct icl_pdu *ip)
+{
+ icl_cxgbei_conn_pdu_queue_cb(ic, ip, NULL);
+}
+
+void
+icl_cxgbei_conn_pdu_queue_cb(struct icl_conn *ic, struct icl_pdu *ip,
+ icl_pdu_cb cb)
{
struct epoch_tracker et;
struct icl_cxgbei_conn *icc = ic_to_icc(ic);
@@ -418,9 +510,12 @@ icl_cxgbei_conn_pdu_queue(struct icl_conn *ic, struct icl_pdu *ip)
MPASS(ip->ip_ahs_mbuf == NULL && ip->ip_ahs_len == 0);
ICL_CONN_LOCK_ASSERT(ic);
+
+ icp->cb = cb;
+
/* NOTE: sowriteable without so_snd lock is a mostly harmless race. */
if (ic->ic_disconnecting || so == NULL || !sowriteable(so)) {
- icl_cxgbei_conn_pdu_free(ic, ip);
+ icl_cxgbei_pdu_done(ip, ENOTCONN);
return;
}
@@ -809,7 +904,7 @@ icl_cxgbei_conn_close(struct icl_conn *ic)
while (!STAILQ_EMPTY(&icc->rcvd_pdus)) {
ip = STAILQ_FIRST(&icc->rcvd_pdus);
STAILQ_REMOVE_HEAD(&icc->rcvd_pdus, ip_next);
- icl_cxgbei_conn_pdu_free(ic, ip);
+ icl_cxgbei_pdu_done(ip, ENOTCONN);
}
SOCKBUF_UNLOCK(sb);
}