netdev - [PATCH net-next] strparser: Add __strp

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Date:   Wed, 6 Jun 2018 09:33:28 -0700
From:   Doron Roberts-Kedes <doronrk@...com>
To:     "David S. Miller" <davem@...emloft.net>
CC:     Dave Watson <davejwatson@...com>, Tom Herbert <tom@...ntonium.net>,
        Vakul Garg <vakul.garg@....com>, <netdev@...r.kernel.org>,
        Doron Roberts-Kedes <doronrk@...com>
Subject: [PATCH net-next] strparser: Add __strp_unpause and use it in ktls.

strp_unpause queues strp_work in order to parse any messages that
arrived while the strparser was paused. However, the process invoking
strp_unpause could eagerly parse a buffered message itself if it held
the sock lock.

__strp_unpause is an alternative to strp_pause that avoids the scheduling
overhead that results when a receiving thread unpauses the strparser
and waits for the next message to be delivered by the workqueue thread.

This patch more than doubled the IOPS achieved in a benchmark of NBD
traffic encrypted using ktls.

Signed-off-by: Doron Roberts-Kedes <doronrk@...com>
---
 include/net/strparser.h   |  2 ++
 net/strparser/strparser.c | 13 +++++++++++++
 net/tls/tls_sw.c          |  2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/net/strparser.h b/include/net/strparser.h
index d96b59f..f177c87 100644
--- a/include/net/strparser.h
+++ b/include/net/strparser.h
@@ -90,6 +90,8 @@ static inline void strp_pause(struct strparser *strp)
 
 /* May be called without holding lock for attached socket */
 void strp_unpause(struct strparser *strp);
+/* Must be called with process lock held (lock_sock) */
+void __strp_unpause(struct strparser *strp);
 
 static inline void save_strp_stats(struct strparser *strp,
 				   struct strp_aggr_stats *agg_stats)
diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
index 092bebc..1a96951 100644
--- a/net/strparser/strparser.c
+++ b/net/strparser/strparser.c
@@ -512,6 +512,19 @@ int strp_init(struct strparser *strp, struct sock *sk,
 }
 EXPORT_SYMBOL_GPL(strp_init);
 
+/* Sock process lock held (lock_sock) */
+void __strp_unpause(struct strparser *strp)
+{
+	strp->paused = 0;
+
+	if (strp->need_bytes) {
+		if (strp_peek_len(strp) < strp->need_bytes)
+			return;
+	}
+	strp_read_sock(strp);
+}
+EXPORT_SYMBOL_GPL(__strp_unpause);
+
 void strp_unpause(struct strparser *strp)
 {
 	strp->paused = 0;
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 839e1e1..8ca57d0 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -735,7 +735,7 @@ static bool tls_sw_advance_skb(struct sock *sk, struct sk_buff *skb,
 	/* Finished with message */
 	ctx->recv_pkt = NULL;
 	kfree_skb(skb);
-	strp_unpause(&ctx->strp);
+	__strp_unpause(&ctx->strp);
 
 	return true;
 }
-- 
2.9.5