linux/lib/kunit/try-catch.c
David Gow 1eb69ded80 kunit: Fix race condition in try-catch completion
KUnit's try-catch infrastructure now uses vfork_done, which is always
set to a valid completion when a kthread is created, but which is set to
NULL once the thread terminates. This creates a race condition, where
the kthread exits before we can wait on it.

Keep a copy of vfork_done, which is taken before we wake_up_process()
and so valid, and wait on that instead.

Fixes: 93533996100c ("kunit: Handle test faults")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/lkml/20240410102710.35911-1-naresh.kamboju@linaro.org/
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Acked-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Tested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2024-05-06 14:22:02 -06:00

117 lines
3.4 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* An API to allow a function, that may fail, to be executed, and recover in a
* controlled manner.
*
* Copyright (C) 2019, Google LLC.
* Author: Brendan Higgins <brendanhiggins@google.com>
*/
#include <kunit/test.h>
#include <linux/completion.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/sched/task.h>
#include "try-catch-impl.h"
void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
{
try_catch->try_result = -EFAULT;
kthread_exit(0);
}
EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
static int kunit_generic_run_threadfn_adapter(void *data)
{
struct kunit_try_catch *try_catch = data;
try_catch->try_result = -EINTR;
try_catch->try(try_catch->context);
if (try_catch->try_result == -EINTR)
try_catch->try_result = 0;
return 0;
}
static unsigned long kunit_test_timeout(void)
{
/*
* TODO(brendanhiggins@google.com): We should probably have some type of
* variable timeout here. The only question is what that timeout value
* should be.
*
* The intention has always been, at some point, to be able to label
* tests with some type of size bucket (unit/small, integration/medium,
* large/system/end-to-end, etc), where each size bucket would get a
* default timeout value kind of like what Bazel does:
* https://docs.bazel.build/versions/master/be/common-definitions.html#test.size
* There is still some debate to be had on exactly how we do this. (For
* one, we probably want to have some sort of test runner level
* timeout.)
*
* For more background on this topic, see:
* https://mike-bland.com/2011/11/01/small-medium-large.html
*
* If tests timeout due to exceeding sysctl_hung_task_timeout_secs,
* the task will be killed and an oops generated.
*/
return 300 * msecs_to_jiffies(MSEC_PER_SEC); /* 5 min */
}
void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
{
struct kunit *test = try_catch->test;
struct task_struct *task_struct;
struct completion *task_done;
int exit_code, time_remaining;
try_catch->context = context;
try_catch->try_result = 0;
task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
try_catch, "kunit_try_catch_thread");
if (IS_ERR(task_struct)) {
try_catch->try_result = PTR_ERR(task_struct);
try_catch->catch(try_catch->context);
return;
}
get_task_struct(task_struct);
/*
* As for a vfork(2), task_struct->vfork_done (pointing to the
* underlying kthread->exited) can be used to wait for the end of a
* kernel thread. It is set to NULL when the thread exits, so we
* keep a copy here.
*/
task_done = task_struct->vfork_done;
wake_up_process(task_struct);
time_remaining = wait_for_completion_timeout(task_done,
kunit_test_timeout());
if (time_remaining == 0) {
try_catch->try_result = -ETIMEDOUT;
kthread_stop(task_struct);
}
put_task_struct(task_struct);
exit_code = try_catch->try_result;
if (!exit_code)
return;
if (exit_code == -EFAULT)
try_catch->try_result = 0;
else if (exit_code == -EINTR) {
if (test->last_seen.file)
kunit_err(test, "try faulted: last line seen %s:%d\n",
test->last_seen.file, test->last_seen.line);
else
kunit_err(test, "try faulted\n");
} else if (exit_code == -ETIMEDOUT)
kunit_err(test, "try timed out\n");
else if (exit_code)
kunit_err(test, "Unknown error: %d\n", exit_code);
try_catch->catch(try_catch->context);
}
EXPORT_SYMBOL_GPL(kunit_try_catch_run);