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kunit: Handle test faults 

Previously, when a kernel test thread crashed (e.g. NULL pointer
dereference, general protection fault), the KUnit test hanged for 30
seconds and exited with a timeout error.

Fix this issue by waiting on task_struct->vfork_done instead of the
custom kunit_try_catch.try_completion, and track the execution state by
initially setting try_result with -EINTR and only setting it to 0 if
the test passed.

Fix kunit_generic_run_threadfn_adapter() signature by returning 0
instead of calling kthread_complete_and_exit().  Because thread's exit
code is never checked, always set it to 0 to make it clear.  To make
this explicit, export kthread_exit() for KUnit tests built as module.

Fix the -EINTR error message, which couldn't be reached until now.

This is tested with a following patch.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Gow <davidgow@google.com>
Tested-by: Rae Moar <rmoar@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-5-mic@digikod.net
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
This commit is contained in:
Mickaël Salaün 2024-04-08 09:46:22 +02:00 committed by Shuah Khan
parent 53026ff63b
commit 3a35c13007
3 changed files with 13 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/kunit/try-catch.h
View File

@ -14,13 +14,11 @@
typedef void (*kunit_try_catch_func_t)(void *);
struct completion;
struct kunit;
/**
* struct kunit_try_catch - provides a generic way to run code which might fail.
* @test: The test case that is currently being executed.
* @try_completion: Completion that the control thread waits on while test runs.
* @try_result: Contains any errno obtained while running test case.
* @try: The function, the test case, to attempt to run.
* @catch: The function called if @try bails out.
@ -46,7 +44,6 @@ struct kunit;
struct kunit_try_catch {
/* private: internal use only. */
struct kunit *test;
struct completion *try_completion;
int try_result;
kunit_try_catch_func_t try;
kunit_try_catch_func_t catch;

1
kernel/kthread.c
View File

@ -315,6 +315,7 @@ void __noreturn kthread_exit(long result)
kthread->result = result;
do_exit(0);
}
EXPORT_SYMBOL(kthread_exit);
/**
* kthread_complete_and_exit - Exit the current kthread.

19
lib/kunit/try-catch.c
View File

@ -18,7 +18,7 @@
void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
{
try_catch->try_result = -EFAULT;
kthread_complete_and_exit(try_catch->try_completion, -EFAULT);
kthread_exit(0);
}
EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
@ -26,9 +26,12 @@ 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;
kthread_complete_and_exit(try_catch->try_completion, 0);
return 0;
}
static unsigned long kunit_test_timeout(void)
@ -58,13 +61,11 @@ static unsigned long kunit_test_timeout(void)
void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
{
DECLARE_COMPLETION_ONSTACK(try_completion);
struct kunit *test = try_catch->test;
struct task_struct *task_struct;
int exit_code, time_remaining;
try_catch->context = context;
try_catch->try_completion = &try_completion;
try_catch->try_result = 0;
task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
try_catch, "kunit_try_catch_thread");
@ -75,8 +76,12 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
}
get_task_struct(task_struct);
wake_up_process(task_struct);
time_remaining = wait_for_completion_timeout(&try_completion,
/*
* 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.
*/
time_remaining = wait_for_completion_timeout(task_struct->vfork_done,
kunit_test_timeout());
if (time_remaining == 0) {
try_catch->try_result = -ETIMEDOUT;
@ -92,7 +97,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
if (exit_code == -EFAULT)
try_catch->try_result = 0;
else if (exit_code == -EINTR)
kunit_err(test, "wake_up_process() was never called\n");
kunit_err(test, "try faulted\n");
else if (exit_code == -ETIMEDOUT)
kunit_err(test, "try timed out\n");
else if (exit_code)