From: Vakul Garg <vakul.garg@nxp.com>
Date: Tue, 12 Mar 2019 08:22:57 +0000
Subject: net/tls: Inform user space about send buffer availability
Patch-mainline: v5.1-rc1
Git-commit: 4504ab0e6eb801555368cbb3011ab0530f659d4b
References: bsc#1109837

A previous fix ("tls: Fix write space handling") assumed that
user space application gets informed about the socket send buffer
availability when tls_push_sg() gets called. Inside tls_push_sg(), in
case do_tcp_sendpages() returns 0, the function returns without calling
ctx->sk_write_space. Further, the new function tls_sw_write_space()
did not invoke ctx->sk_write_space. This leads to situation that user
space application encounters a lockup always waiting for socket send
buffer to become available.

Rather than call ctx->sk_write_space from tls_push_sg(), it should be
called from tls_write_space. So whenever tcp stack invokes
sk->sk_write_space after freeing socket send buffer, we always declare
the same to user space by the way of invoking ctx->sk_write_space.

Fixes: 7463d3a2db0ef ("tls: Fix write space handling")
Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Reviewed-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/tls/tls_device.c |    3 ---
 net/tls/tls_main.c   |    3 ++-
 2 files changed, 2 insertions(+), 4 deletions(-)

--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -555,9 +555,6 @@ void tls_device_write_space(struct sock
 					     MSG_DONTWAIT | MSG_NOSIGNAL);
 		sk->sk_allocation = sk_allocation;
 	}
-
-	if (!rc)
-		ctx->sk_write_space(sk);
 }
 
 void handle_device_resync(struct sock *sk, u32 seq, u64 rcd_sn)
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -144,7 +144,6 @@ retry:
 	}
 
 	ctx->in_tcp_sendpages = false;
-	ctx->sk_write_space(sk);
 
 	return 0;
 }
@@ -226,6 +225,8 @@ static void tls_write_space(struct sock
 	else
 #endif
 		tls_sw_write_space(sk, ctx);
+
+	ctx->sk_write_space(sk);
 }
 
 static void tls_ctx_free(struct tls_context *ctx)