[PATCH v4 12/14] cmd: add spawn and wait commands
Ilias Apalodimas
ilias.apalodimas at linaro.org
Tue Mar 18 12:16:57 CET 2025
On Tue, 18 Mar 2025 at 12:47, Jerome Forissier
<jerome.forissier at linaro.org> wrote:
>
> Add a spawn command which runs another command in the background, as
> well as a wait command to suspend the shell until one or more background
> jobs have completed. The job_id environment variable is set by spawn and
> wait accepts optional job ids, so that one can selectively wait on any
> job.
>
> Example:
>
> => date; spawn sleep 5; spawn sleep 3; date; echo "waiting..."; wait; date
> Date: 2025-02-21 (Friday) Time: 17:04:52
> Date: 2025-02-21 (Friday) Time: 17:04:52
> waiting...
> Date: 2025-02-21 (Friday) Time: 17:04:57
> =>
>
> Another example showing how background jobs can make initlizations
> faster. The board is i.MX93 EVK, with one spinning HDD connected to
> USB1 via a hub, and a network cable plugged into ENET1.
>
> # From power up / reset
> u-boot=> setenv autoload 0
> u-boot=> setenv ud "usb start; dhcp"
> u-boot=> time run ud
> [...]
> time: 8.058 seconds
>
> # From power up / reset
> u-boot=> setenv autoload 0
> u-boot=> setenv ud "spawn usb start; spawn dhcp; wait"
> u-boot=> time run ud
> [...]
> time: 4.475 seconds
>
> Signed-off-by: Jerome Forissier <jerome.forissier at linaro.org>
> ---
> cmd/Kconfig | 17 +++++
> cmd/Makefile | 2 +
> cmd/spawn.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 207 insertions(+)
> create mode 100644 cmd/spawn.c
>
> diff --git a/cmd/Kconfig b/cmd/Kconfig
> index cd391d422ae..0cbb75edfbe 100644
> --- a/cmd/Kconfig
> +++ b/cmd/Kconfig
> @@ -3079,4 +3079,21 @@ config CMD_MESON
> help
> Enable useful commands for the Meson Soc family developed by Amlogic Inc.
>
> +config CMD_SPAWN
> + bool "spawn and wait commands"
> + depends on UTHREAD
> + help
> + spawn runs a command in the background and sets the job_id environment
> + variable. wait is used to suspend the shell execution until one or more
> + jobs are complete.
> +
> +config CMD_SPAWN_NUM_JOBS
> + int "Maximum number of simultaneous jobs for spawn"
> + default 16
> + help
> + Job identifiers are in the range 1..CMD_SPAWN_NUM_JOBS. In other words
> + there can be no more that CMD_SPAWN_NUM_JOBS running simultaneously.
> + When a jobs exits, its identifier is available to be re-used by the next
> + spawn command.
> +
> endif
> diff --git a/cmd/Makefile b/cmd/Makefile
> index c1275d466c8..b61f6586157 100644
> --- a/cmd/Makefile
> +++ b/cmd/Makefile
> @@ -239,6 +239,8 @@ obj-$(CONFIG_CMD_SCP03) += scp03.o
>
> obj-$(CONFIG_HUSH_SELECTABLE) += cli.o
>
> +obj-$(CONFIG_CMD_SPAWN) += spawn.o
> +
> obj-$(CONFIG_ARM) += arm/
> obj-$(CONFIG_RISCV) += riscv/
> obj-$(CONFIG_SANDBOX) += sandbox/
> diff --git a/cmd/spawn.c b/cmd/spawn.c
> new file mode 100644
> index 00000000000..f7a9f225f93
> --- /dev/null
> +++ b/cmd/spawn.c
> @@ -0,0 +1,188 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2011 The Chromium OS Authors.
> + */
> +
> +#include <command.h>
> +#include <console.h>
> +#include <malloc.h>
> +#include <vsprintf.h>
> +#include <uthread.h>
> +
> +/* Spawn arguments and job index */
> +struct spa {
> + int argc;
> + char **argv;
> + unsigned int job_idx;
> +};
> +
> +/*
> + * uthread group identifiers for each running job
> + * 0: job slot available, != 0: uthread group id
> + * Note that job[0] is job_id 1, job[1] is job_id 2 etc.
> + */
> +static unsigned int job[CONFIG_CMD_SPAWN_NUM_JOBS];
> +/*
> + * Return values of the commands run as jobs */
> +static enum command_ret_t job_ret[CONFIG_CMD_SPAWN_NUM_JOBS];
> +
> +static void spa_free(struct spa *spa)
> +{
> + int i;
> +
> + if (!spa)
> + return;
> +
> + for (i = 0; i < spa->argc; i++)
> + free(spa->argv[i]);
> + free(spa->argv);
> + free(spa);
> +}
> +
> +static struct spa *spa_create(int argc, char *const argv[])
> +{
> + struct spa *spa;
> + int i;
> +
> + spa = calloc(1, sizeof(*spa));
> + if (!spa)
> + return NULL;
> + spa->argc = argc;
> + spa->argv = malloc(argc * sizeof(char *));
> + if (!spa->argv)
> + goto err;
> + for (i = 0; i < argc; i++) {
> + spa->argv[i] = strdup(argv[i]);
> + if (!spa->argv[i])
> + goto err;
> + }
> + return spa;
> +err:
> + spa_free(spa);
> + return NULL;
> +}
> +
> +static void spawn_thread(void *arg)
> +{
> + struct spa *spa = (struct spa *)arg;
> + ulong cycles = 0;
> + int repeatable = 0;
> +
> + job_ret[spa->job_idx] = cmd_process(0, spa->argc, spa->argv,
> + &repeatable, &cycles);
> + spa_free(spa);
> +}
> +
> +static unsigned int next_job_id(void)
> +{
> + int i;
> +
> + for (i = 0; i < CONFIG_CMD_SPAWN_NUM_JOBS; i++)
> + if (!job[i])
> + return i + 1;
> +
> + /* No job available */
> + return 0;
> +}
> +
> +static void refresh_jobs(void)
> +{
> + int i;
> +
> + for (i = 0; i < CONFIG_CMD_SPAWN_NUM_JOBS; i++)
> + if (job[i] && uthread_grp_done(job[i]))
> + job[i] = 0;
> +
> +}
> +
> +static int do_spawn(struct cmd_tbl *cmdtp, int flag, int argc,
> + char *const argv[])
> +{
> + unsigned int id;
> + unsigned int idx;
> + struct spa *spa;
> + int ret;
> +
> + if (argc == 1)
> + return CMD_RET_USAGE;
> +
> + spa = spa_create(argc - 1, argv + 1);
> + if (!spa)
> + return CMD_RET_FAILURE;
> +
> + refresh_jobs();
> +
> + id = next_job_id();
> + if (!id)
> + return CMD_RET_FAILURE;
> + idx = id - 1;
> +
> + job[idx] = uthread_grp_new_id();
> +
> + ret = uthread_create(NULL, spawn_thread, spa, 0, job[idx]);
> + if (ret) {
> + job[idx] = 0;
> + return CMD_RET_FAILURE;
> + }
> +
> + ret = env_set_ulong("job_id", id);
> + if (ret)
> + return CMD_RET_FAILURE;
> +
> + return CMD_RET_SUCCESS;
> +}
> +
> +U_BOOT_CMD(spawn, CONFIG_SYS_MAXARGS, 0, do_spawn,
> + "run commands and summarize execution time",
> + "command [args...]\n");
> +
> +static enum command_ret_t wait_job(unsigned int idx)
> +{
> + int prev = disable_ctrlc(false);
> +
> + while (!uthread_grp_done(job[idx])) {
> + if (ctrlc()) {
> + puts("<INTERRUPT>\n");
> + disable_ctrlc(prev);
> + return CMD_RET_FAILURE;
> + }
> + uthread_schedule();
> + }
> +
> + job[idx] = 0;
> + disable_ctrlc(prev);
> +
> + return job_ret[idx];
> +}
> +
> +static int do_wait(struct cmd_tbl *cmdtp, int flag, int argc,
> + char *const argv[])
> +{
> + enum command_ret_t ret = CMD_RET_SUCCESS;
> + unsigned long id;
> + unsigned int idx;
> + int i;
> +
> + if (argc == 1) {
> + for (i = 0; i < CONFIG_CMD_SPAWN_NUM_JOBS; i++)
> + if (job[idx])
> + ret = wait_job(i);
> + } else {
> + for (i = 1; i < argc; i++) {
> + id = dectoul(argv[i], NULL);
> + if (id < 0 || id > CONFIG_CMD_SPAWN_NUM_JOBS)
> + return CMD_RET_USAGE;
> + idx = (int)id - 1;
> + ret = wait_job(idx);
> + }
> + }
> +
> + return ret;
> +}
> +
> +U_BOOT_CMD(wait, CONFIG_SYS_MAXARGS, 0, do_wait,
> + "wait for one or more jobs to complete",
> + "[job_id ...]\n"
> + " - Wait until all specified jobs have exited and return the\n"
> + " exit status of the last job waited for. When no job_id is\n"
> + " given, wait for all the background jobs.\n");
> --
> 2.43.0
>
Acked-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
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