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Date: Tue, 13 Feb 2024 20:53:52 -0800
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Subject: [PATCH v4 4/8] tools subcmd: Add a no exec function call option
From: Ian Rogers <irogers@google.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, 
	Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung Kim <namhyung@kernel.org>, 
	Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Ian Rogers <irogers@google.com>, Adrian Hunter <adrian.hunter@intel.com>, 
	Nathan Chancellor <nathan@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, 
	Bill Wendling <morbo@google.com>, Justin Stitt <justinstitt@google.com>, 
	James Clark <james.clark@arm.com>, Athira Jajeev <atrajeev@linux.vnet.ibm.com>, 
	Kan Liang <kan.liang@linux.intel.com>, Yang Jihong <yangjihong1@huawei.com>, 
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, 
	llvm@lists.linux.dev
Content-Type: text/plain; charset="UTF-8"

Tools like perf fork tests in case they crash, but they don't want to
exec a full binary. Add an option to call a function rather than do an
exec. The child process exits with the result of the function call and
is passed the struct of the run_command, things like container_of can
then allow the child process function to determine additional
arguments.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/subcmd/run-command.c | 2 ++
 tools/lib/subcmd/run-command.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
index 5cdac2162532..d435eb42354b 100644
--- a/tools/lib/subcmd/run-command.c
+++ b/tools/lib/subcmd/run-command.c
@@ -122,6 +122,8 @@ int start_command(struct child_process *cmd)
 		}
 		if (cmd->preexec_cb)
 			cmd->preexec_cb();
+		if (cmd->no_exec_cmd)
+			exit(cmd->no_exec_cmd(cmd));
 		if (cmd->exec_cmd) {
 			execv_cmd(cmd->argv);
 		} else {
diff --git a/tools/lib/subcmd/run-command.h b/tools/lib/subcmd/run-command.h
index 17d969c6add3..d794138a797f 100644
--- a/tools/lib/subcmd/run-command.h
+++ b/tools/lib/subcmd/run-command.h
@@ -47,6 +47,8 @@ struct child_process {
 	unsigned exec_cmd:1; /* if this is to be external sub-command */
 	unsigned stdout_to_stderr:1;
 	void (*preexec_cb)(void);
+	 /* If set, call function in child rather than doing an exec. */
+	int (*no_exec_cmd)(struct child_process *process);
 };
 
 int start_command(struct child_process *);
-- 
2.43.0.687.g38aa6559b0-goog