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@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 16 insertions, 1 deletions

diff --git a/include/net/strparser.h b/include/net/strparser.h
index d96b59f45eba..f177c87ce38b 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 092bebc70048..1a9695183599 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 839e1e165a0c..8ca57d01b18f 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;
 }