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Message-Id: <5b693dc83bbe115a020af81faa4439d0fdf44abf.1518718761.git.sowmini.varadhan@oracle.com>
Date: Thu, 15 Feb 2018 10:49:35 -0800
From: Sowmini Varadhan <sowmini.varadhan@...cle.com>
To: sowmini.varadhan@...cle.com, netdev@...r.kernel.org,
willemdebruijn.kernel@...il.com
Cc: davem@...emloft.net, rds-devel@....oracle.com,
santosh.shilimkar@...cle.com
Subject: [PATCH v3 net-next 4/7] rds: support for zcopy completion notification
RDS removes a datagram (rds_message) from the retransmit queue when
an ACK is received. The ACK indicates that the receiver has queued
the RDS datagram, so that the sender can safely forget the datagram.
When all references to the rds_message are quiesced, rds_message_purge
is called to release resources used by the rds_message
If the datagram to be removed had pinned pages set up, add
an entry to the rs->rs_znotify_queue so that the notifcation
will be sent up via rds_rm_zerocopy_callback() when the
rds_message is eventually freed by rds_message_purge.
rds_rm_zerocopy_callback() attempts to batch the number of cookies
sent with each notification to a max of SO_EE_ORIGIN_MAX_ZCOOKIES.
This is achieved by checking the tail skb in the sk_error_queue:
if this has room for one more cookie, the cookie from the
current notification is added; else a new skb is added to the
sk_error_queue. Every invocation of rds_rm_zerocopy_callback() will
trigger a ->sk_error_report to notify the application.
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
---
v2:
- make sure to always sock_put m_rs even if there is no znotifier.
- major rewrite of notification, resulting in much simplification.
v3:
- fix fragile use of skb->cb[], do not set ee_code incorrectly.
include/uapi/linux/errqueue.h | 2 +
net/rds/af_rds.c | 2 +
net/rds/message.c | 83 +++++++++++++++++++++++++++++++++++++---
net/rds/rds.h | 14 +++++++
net/rds/recv.c | 2 +
5 files changed, 96 insertions(+), 7 deletions(-)
diff --git a/include/uapi/linux/errqueue.h b/include/uapi/linux/errqueue.h
index dc64cfa..28812ed 100644
--- a/include/uapi/linux/errqueue.h
+++ b/include/uapi/linux/errqueue.h
@@ -20,11 +20,13 @@ struct sock_extended_err {
#define SO_EE_ORIGIN_ICMP6 3
#define SO_EE_ORIGIN_TXSTATUS 4
#define SO_EE_ORIGIN_ZEROCOPY 5
+#define SO_EE_ORIGIN_ZCOOKIE 6
#define SO_EE_ORIGIN_TIMESTAMPING SO_EE_ORIGIN_TXSTATUS
#define SO_EE_OFFENDER(ee) ((struct sockaddr*)((ee)+1))
#define SO_EE_CODE_ZEROCOPY_COPIED 1
+#define SO_EE_ORIGIN_MAX_ZCOOKIES 8
/**
* struct scm_timestamping - timestamps exposed through cmsg
diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index 0a8eefd..a937f18 100644
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -182,6 +182,8 @@ static __poll_t rds_poll(struct file *file, struct socket *sock,
mask |= (EPOLLIN | EPOLLRDNORM);
if (rs->rs_snd_bytes < rds_sk_sndbuf(rs))
mask |= (EPOLLOUT | EPOLLWRNORM);
+ if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
+ mask |= POLLERR;
read_unlock_irqrestore(&rs->rs_recv_lock, flags);
/* clear state any time we wake a seen-congested socket */
diff --git a/net/rds/message.c b/net/rds/message.c
index ef3daaf..bf1a656 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -33,6 +33,9 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/export.h>
+#include <linux/skbuff.h>
+#include <linux/list.h>
+#include <linux/errqueue.h>
#include "rds.h"
@@ -53,29 +56,95 @@ void rds_message_addref(struct rds_message *rm)
}
EXPORT_SYMBOL_GPL(rds_message_addref);
+static inline bool skb_zcookie_add(struct sk_buff *skb, u32 cookie)
+{
+ struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
+ int ncookies;
+ u32 *ptr;
+
+ if (serr->ee.ee_origin != SO_EE_ORIGIN_ZCOOKIE)
+ return false;
+ ncookies = serr->ee.ee_data;
+ if (ncookies == SO_EE_ORIGIN_MAX_ZCOOKIES)
+ return false;
+ ptr = skb_put(skb, sizeof(u32));
+ *ptr = cookie;
+ serr->ee.ee_data = ++ncookies;
+ return true;
+}
+
+static void rds_rm_zerocopy_callback(struct rds_sock *rs,
+ struct rds_znotifier *znotif)
+{
+ struct sock *sk = rds_rs_to_sk(rs);
+ struct sk_buff *skb, *tail;
+ struct sock_exterr_skb *serr;
+ unsigned long flags;
+ struct sk_buff_head *q;
+ u32 cookie = znotif->z_cookie;
+
+ q = &sk->sk_error_queue;
+ spin_lock_irqsave(&q->lock, flags);
+ tail = skb_peek_tail(q);
+
+ if (tail && skb_zcookie_add(tail, cookie)) {
+ spin_unlock_irqrestore(&q->lock, flags);
+ mm_unaccount_pinned_pages(&znotif->z_mmp);
+ consume_skb(rds_skb_from_znotifier(znotif));
+ sk->sk_error_report(sk);
+ return;
+ }
+
+ skb = rds_skb_from_znotifier(znotif);
+ serr = SKB_EXT_ERR(skb);
+ memset(&serr->ee, 0, sizeof(serr->ee));
+ serr->ee.ee_errno = 0;
+ serr->ee.ee_origin = SO_EE_ORIGIN_ZCOOKIE;
+ serr->ee.ee_info = 0;
+ WARN_ON(!skb_zcookie_add(skb, cookie));
+
+ __skb_queue_tail(q, skb);
+
+ spin_unlock_irqrestore(&q->lock, flags);
+ sk->sk_error_report(sk);
+
+ mm_unaccount_pinned_pages(&znotif->z_mmp);
+}
+
/*
* This relies on dma_map_sg() not touching sg[].page during merging.
*/
static void rds_message_purge(struct rds_message *rm)
{
unsigned long i, flags;
+ bool zcopy = false;
if (unlikely(test_bit(RDS_MSG_PAGEVEC, &rm->m_flags)))
return;
- for (i = 0; i < rm->data.op_nents; i++) {
- rdsdebug("putting data page %p\n", (void *)sg_page(&rm->data.op_sg[i]));
- /* XXX will have to put_page for page refs */
- __free_page(sg_page(&rm->data.op_sg[i]));
- }
- rm->data.op_nents = 0;
spin_lock_irqsave(&rm->m_rs_lock, flags);
if (rm->m_rs) {
- sock_put(rds_rs_to_sk(rm->m_rs));
+ struct rds_sock *rs = rm->m_rs;
+
+ if (rm->data.op_mmp_znotifier) {
+ zcopy = true;
+ rds_rm_zerocopy_callback(rs, rm->data.op_mmp_znotifier);
+ rm->data.op_mmp_znotifier = NULL;
+ }
+ sock_put(rds_rs_to_sk(rs));
rm->m_rs = NULL;
}
spin_unlock_irqrestore(&rm->m_rs_lock, flags);
+ for (i = 0; i < rm->data.op_nents; i++) {
+ /* XXX will have to put_page for page refs */
+ if (!zcopy)
+ __free_page(sg_page(&rm->data.op_sg[i]));
+ else
+ put_page(sg_page(&rm->data.op_sg[i]));
+ }
+ rm->data.op_nents = 0;
+
if (rm->rdma.op_active)
rds_rdma_free_op(&rm->rdma);
if (rm->rdma.op_rdma_mr)
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 7301b9b..24576bc 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -356,6 +356,19 @@ static inline u32 rds_rdma_cookie_offset(rds_rdma_cookie_t cookie)
#define RDS_MSG_PAGEVEC 7
#define RDS_MSG_FLUSH 8
+struct rds_znotifier {
+ struct list_head z_list;
+ struct mmpin z_mmp;
+ u32 z_cookie;
+};
+
+#define RDS_ZCOPY_SKB(__skb) ((struct rds_znotifier *)&((__skb)->cb[0]))
+
+static inline struct sk_buff *rds_skb_from_znotifier(struct rds_znotifier *z)
+{
+ return container_of((void *)z, struct sk_buff, cb);
+}
+
struct rds_message {
refcount_t m_refcount;
struct list_head m_sock_item;
@@ -436,6 +449,7 @@ struct rds_message {
unsigned int op_count;
unsigned int op_dmasg;
unsigned int op_dmaoff;
+ struct rds_znotifier *op_mmp_znotifier;
struct scatterlist *op_sg;
} data;
};
diff --git a/net/rds/recv.c b/net/rds/recv.c
index b25bcfe..b080961 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -594,6 +594,8 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
if (msg_flags & MSG_OOB)
goto out;
+ if (msg_flags & MSG_ERRQUEUE)
+ return sock_recv_errqueue(sk, msg, size, SOL_IP, IP_RECVERR);
while (1) {
/* If there are pending notifications, do those - and nothing else */
--
1.7.1
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