From 9767c4db0ed9dd6fe96bc784db4e210875a96fd3 Mon Sep 17 00:00:00 2001
From: Sebastian Sumpf <sebastian.sumpf@genode-labs.com>
Date: Fri, 6 Dec 2019 14:12:04 +0100
Subject: [PATCH] vfs_lwip/lwip: Lwip::lock for concurrent access

This is required in case the send and receive of IP packets is
performed by multiple thread because lwip is not thread safe.

issue #3568
---
 repos/libports/include/lwip/genode_init.h     |  6 ++++-
 repos/libports/include/lwip/nic_netif.h       |  2 ++
 .../src/lib/lwip/platform/sys_arch.cc         | 13 ++++++++--
 repos/libports/src/lib/vfs/lwip/vfs.cc        | 25 ++++++++++---------
 4 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/repos/libports/include/lwip/genode_init.h b/repos/libports/include/lwip/genode_init.h
index 531c6ac3e..e315e9f43 100644
--- a/repos/libports/include/lwip/genode_init.h
+++ b/repos/libports/include/lwip/genode_init.h
@@ -17,6 +17,10 @@
 #include <timer/timeout.h>
 #include <base/allocator.h>
 
-namespace Lwip { void genode_init(Genode::Allocator &heap, Genode::Timeout_scheduler &timer); }
+namespace Lwip {
+	void genode_init(Genode::Allocator &heap, Genode::Timeout_scheduler &timer);
+
+	Genode::Lock &lock();
+}
 
 #endif
diff --git a/repos/libports/include/lwip/nic_netif.h b/repos/libports/include/lwip/nic_netif.h
index 2ee932bfc..b6579bbfd 100644
--- a/repos/libports/include/lwip/nic_netif.h
+++ b/repos/libports/include/lwip/nic_netif.h
@@ -26,6 +26,7 @@
 #endif
 
 /* Genode includes */
+#include <lwip/genode_init.h>
 #include <nic/packet_allocator.h>
 #include <nic_session/connection.h>
 #include <base/log.h>
@@ -140,6 +141,7 @@ class Lwip::Nic_netif
 
 		void handle_rx_packets()
 		{
+			Genode::Lock::Guard g { Lwip::lock() };
 			auto &rx = *_nic.rx();
 
 			while (rx.packet_avail() && rx.ready_to_ack()) {
diff --git a/repos/libports/src/lib/lwip/platform/sys_arch.cc b/repos/libports/src/lib/lwip/platform/sys_arch.cc
index c3b7087f3..2963b1480 100644
--- a/repos/libports/src/lib/lwip/platform/sys_arch.cc
+++ b/repos/libports/src/lib/lwip/platform/sys_arch.cc
@@ -36,8 +36,11 @@ namespace Lwip {
 
 	struct Sys_timer
 	{
-		void check_timeouts(Genode::Duration) {
-			sys_check_timeouts(); }
+		void check_timeouts(Genode::Duration)
+		{
+			Genode::Lock::Guard g{ Lwip::lock() };
+			sys_check_timeouts();
+		}
 
 		Genode::Timeout_scheduler &timer;
 
@@ -62,6 +65,12 @@ namespace Lwip {
 
 		lwip_init();
 	}
+
+	Genode::Lock &lock()
+	{
+		static Genode::Lock _lwip_lock;
+		return _lwip_lock;
+	}
 }
 
 
diff --git a/repos/libports/src/lib/vfs/lwip/vfs.cc b/repos/libports/src/lib/vfs/lwip/vfs.cc
index 51df283c9..86ab57f01 100644
--- a/repos/libports/src/lib/vfs/lwip/vfs.cc
+++ b/repos/libports/src/lib/vfs/lwip/vfs.cc
@@ -898,6 +898,7 @@ class Lwip::Udp_socket_dir final :
 		                 char *dst, file_size count,
 		                 file_size &out_count) override
 		{
+			Genode::Lock::Guard g { Lwip::lock() };
 			Read_result result = Read_result::READ_ERR_INVALID;
 
 			switch(handle.kind) {
@@ -983,6 +984,8 @@ class Lwip::Udp_socket_dir final :
 		                   char const *src, file_size count,
 		                   file_size &out_count) override
 		{
+			Genode::Lock::Guard g { Lwip::lock() };
+
 			switch(handle.kind) {
 
 			case Lwip_file_handle::DATA: {
@@ -1287,6 +1290,8 @@ class Lwip::Tcp_socket_dir final :
 		                 char *dst, file_size count,
 		                 file_size &out_count) override
 		{
+			Genode::Lock::Guard g { Lwip::lock() };
+
 			switch(handle.kind) {
 
 			case Lwip_file_handle::DATA:
@@ -1371,7 +1376,11 @@ class Lwip::Tcp_socket_dir final :
 
 					handle.kind = Lwip_file_handle::LOCATION;
 					/* read the location of the new socket directory */
-					return handle.read(dst, count, out_count);
+					Lwip::lock().unlock();
+					Read_result result = handle.read(dst, count, out_count);
+					Lwip::lock().lock();
+
+					return result;
 				}
 
 				return Read_result::READ_QUEUED;
@@ -1433,6 +1442,7 @@ class Lwip::Tcp_socket_dir final :
 		                   char const *src, file_size count,
 		                   file_size &out_count) override
 		{
+			Genode::Lock::Guard g { Lwip::lock() };
 			if (_pcb == NULL) {
 				/* socket is closed */
 				return Write_result::WRITE_ERR_IO;
@@ -1958,17 +1968,8 @@ class Lwip::File_system final : public Vfs::File_system, public Lwip::Directory
 			if ((vfs_handle->status_flags() & OPEN_MODE_ACCMODE) == OPEN_MODE_RDONLY)
 				return Write_result::WRITE_ERR_INVALID;
 			if (Lwip_handle *handle = dynamic_cast<Lwip_handle*>(vfs_handle)) {
-				while (true) {
-					res = handle->write(src, count, out_count);
-					if (res != WRITE_ERR_WOULD_BLOCK || out_count) break;
-
-					/*
-					 * XXX: block for signals until the write completes
-					 * or fails, this is not how it should be done, but
-					 * it's how lxip does it
-					 */
-					_ep.wait_and_dispatch_one_io_signal();
-				}
+				res = handle->write(src, count, out_count);
+				if (res == WRITE_ERR_WOULD_BLOCK) throw Insufficient_buffer();
 			}
 			return res;
 		}