Merge patch series "Uthreads"

Jerome Forissier <jerome.forissier@linaro.org> says:

This series introduces threads and uses them to improve the performance
of the USB bus scanning code and to implement background jobs in the
shell via two new commands: 'spawn' and 'wait'.

The threading framework is called 'uthread' and is inspired from the
barebox threads [2]. setjmp() and longjmp() are used to save and
restore contexts, as well as a non-standard extension called initjmp().
This new function is added in several patches, one for each
architecture that supports HAVE_SETJMP. A new symbol is defined:
HAVE_INITJMP. Two tests, one for initjmp() and one for the uthread
scheduling, are added to the lib suite.

After introducing threads and making schedule() and udelay() a thread
re-scheduling point, the USB stack initialization is modified to benefit
from concurrency when UTHREAD is enabled, where uthreads are used in
usb_init() to initialize and scan multiple busses at the same time.
The code was tested on arm64 and arm QEMU with 4 simulated XHCI buses
and some devices. On this platform the USB scan takes 2.2 s instead of
5.6 s. Tested on i.MX93 EVK with two USB hubs, one ethernet adapter and
one webcam on each, "usb start" takes 2.4 s instead of 4.6 s.

Finally, the spawn and wait commands are introduced, allowing the use of
threads from the shell. Tested on the i.MX93 EVK with a spinning HDD
connected to USB1 and the network connected to ENET1. The USB plus DHCP
init sequence "spawn usb start; spawn dhcp; wait" takes 4.5 seconds
instead of 8 seconds for "usb start; dhcp".

[1] https://patchwork.ozlabs.org/project/uboot/list/?series=446674
[2] https://github.com/barebox/barebox/blob/master/common/bthread.c

Link: https://lore.kernel.org/r/20250418141114.2056981-1-jerome.forissier@linaro.org

1 files changed, 32 insertions, 0 deletions

diff --git a/test/cmd/spawn.c b/test/cmd/spawn.c
new file mode 100644
index 00000000000..8f48f5ee25c
--- /dev/null
+++ b/test/cmd/spawn.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Tests for spawn and wait commands
+ *
+ * Copyright 2025, Linaro Ltd.
+ */
+
+#include <command.h>
+#include <test/cmd.h>
+#include <test/test.h>
+#include <test/ut.h>
+
+static int test_cmd_spawn(struct unit_test_state *uts)
+{
+	ut_assertok(run_command("wait; spawn sleep 2; setenv j ${job_id}; "
+				"spawn setenv spawned true; "
+				"setenv jj ${job_id}; wait; "
+				"echo ${j} ${jj} ${spawned}", 0));
+	console_record_readline(uts->actual_str, sizeof(uts->actual_str));
+	ut_asserteq_ptr(uts->actual_str,
+			strstr(uts->actual_str, "1 2 true"));
+
+	ut_assertok(run_command("spawn true; wait; setenv t $?; spawn false; "
+				"wait; setenv f $?; wait; echo $t $f $?", 0));
+	console_record_readline(uts->actual_str, sizeof(uts->actual_str));
+	ut_asserteq_ptr(uts->actual_str,
+			strstr(uts->actual_str, "0 1 0"));
+	ut_assert_console_end();
+
+	return 0;
+}
+CMD_TEST(test_cmd_spawn, UTF_CONSOLE);