Hi,
This patch series teaches KUnit to handle kthread faults as errors, and
it brings a few related fixes and improvements.
Shuah, everything should be OK now, could you please merge this series?
All these tests pass (on top of v6.8):
/tools/testing/kunit/kunit.py run --alltests
/tools/testing/kunit/kunit.py run --alltests --arch x86_64
/tools/testing/kunit/kunit.py run --alltests --arch arm64 \
--cross_compile=aarch64-linux-gnu-
I added Reviewed-by, Tested-by and Fixes tags according to previous
review. I improved a commit message and added a comment.
A new test case check NULL pointer dereference, which wasn't possible
before.
This is useful to test current kernel self-protection mechanisms or
future ones such as Heki: https://github.com/heki-linux
Previous version:
v2: https://lore.kernel.org/r/[email protected]
v1: https://lore.kernel.org/r/[email protected]
Regards,
Mickaël Salaün (7):
kunit: Handle thread creation error
kunit: Fix kthread reference
kunit: Fix timeout message
kunit: Handle test faults
kunit: Fix KUNIT_SUCCESS() calls in iov_iter tests
kunit: Print last test location on fault
kunit: Add tests for fault
include/kunit/test.h | 24 ++++++++++++++++++---
include/kunit/try-catch.h | 3 ---
lib/kunit/kunit-test.c | 45 ++++++++++++++++++++++++++++++++++++++-
lib/kunit/try-catch.c | 38 ++++++++++++++++++++++-----------
lib/kunit_iov_iter.c | 18 ++++++++--------
5 files changed, 100 insertions(+), 28 deletions(-)
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
--
2.44.0
There is a race condition when a kthread finishes after the deadline and
before the call to kthread_stop(), which may lead to use after free.
Cc: Brendan Higgins <[email protected]>
Cc: Shuah Khan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Fixes: adf505457032 ("kunit: fix UAF when run kfence test case test_gfpzero")
Reviewed-by: David Gow <[email protected]>
Reviewed-by: Rae Moar <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
Changes since v2:
* Add Fixes tag as suggested by David.
* Add David's and Rae's Reviewed-by.
Changes since v1:
* Add Kees's Reviewed-by.
---
lib/kunit/try-catch.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index a5cb2ef70a25..73f5007f20ea 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -11,6 +11,7 @@
#include <linux/completion.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
+#include <linux/sched/task.h>
#include "try-catch-impl.h"
@@ -65,14 +66,15 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
try_catch->context = context;
try_catch->try_completion = &try_completion;
try_catch->try_result = 0;
- task_struct = kthread_run(kunit_generic_run_threadfn_adapter,
- try_catch,
- "kunit_try_catch_thread");
+ 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);
+ wake_up_process(task_struct);
time_remaining = wait_for_completion_timeout(&try_completion,
kunit_test_timeout());
@@ -82,6 +84,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
kthread_stop(task_struct);
}
+ put_task_struct(task_struct);
exit_code = try_catch->try_result;
if (!exit_code)
--
2.44.0
Previously, if a thread creation failed (e.g. -ENOMEM), the function was
called (kunit_catch_run_case or kunit_catch_run_case_cleanup) without
marking the test as failed. Instead, fill try_result with the error
code returned by kthread_run(), which will mark the test as failed and
print "internal error occurred...".
Cc: Brendan Higgins <[email protected]>
Cc: Shuah Khan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Rae Moar <[email protected]>
Reviewed-by: David Gow <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
Changes since v2:
* Add Rae's and David's Reviewed-by.
Changes since v1:
* Add Kees's Reviewed-by.
---
lib/kunit/try-catch.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index f7825991d576..a5cb2ef70a25 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -69,6 +69,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
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;
}
--
2.44.0
This helps identify the location of test faults with opportunistic calls
to _KUNIT_SAVE_LOC(). This can be useful while writing tests or
debugging them. It is possible to call KUNIT_SUCCESS() to explicit save
last location.
Cc: Brendan Higgins <[email protected]>
Cc: David Gow <[email protected]>
Cc: Rae Moar <[email protected]>
Cc: Shuah Khan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
Changes since v2:
* Extend the commit message according to discussion with David.
Changes since v1:
* Add Kees's Reviewed-by.
---
include/kunit/test.h | 24 +++++++++++++++++++++---
lib/kunit/try-catch.c | 10 +++++++---
2 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/include/kunit/test.h b/include/kunit/test.h
index fcb4a4940ace..f3aa66eb0087 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -301,6 +301,8 @@ struct kunit {
struct list_head resources; /* Protected by lock. */
char status_comment[KUNIT_STATUS_COMMENT_SIZE];
+ /* Saves the last seen test. Useful to help with faults. */
+ struct kunit_loc last_seen;
};
static inline void kunit_set_failure(struct kunit *test)
@@ -567,6 +569,15 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
#define kunit_err(test, fmt, ...) \
kunit_printk(KERN_ERR, test, fmt, ##__VA_ARGS__)
+/*
+ * Must be called at the beginning of each KUNIT_*_ASSERTION().
+ * Cf. KUNIT_CURRENT_LOC.
+ */
+#define _KUNIT_SAVE_LOC(test) do { \
+ WRITE_ONCE(test->last_seen.file, __FILE__); \
+ WRITE_ONCE(test->last_seen.line, __LINE__); \
+} while (0)
+
/**
* KUNIT_SUCCEED() - A no-op expectation. Only exists for code clarity.
* @test: The test context object.
@@ -575,7 +586,7 @@ void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt,
* words, it does nothing and only exists for code clarity. See
* KUNIT_EXPECT_TRUE() for more information.
*/
-#define KUNIT_SUCCEED(test) do {} while (0)
+#define KUNIT_SUCCEED(test) _KUNIT_SAVE_LOC(test)
void __noreturn __kunit_abort(struct kunit *test);
@@ -601,14 +612,16 @@ void __kunit_do_failed_assertion(struct kunit *test,
} while (0)
-#define KUNIT_FAIL_ASSERTION(test, assert_type, fmt, ...) \
+#define KUNIT_FAIL_ASSERTION(test, assert_type, fmt, ...) do { \
+ _KUNIT_SAVE_LOC(test); \
_KUNIT_FAILED(test, \
assert_type, \
kunit_fail_assert, \
kunit_fail_assert_format, \
{}, \
fmt, \
- ##__VA_ARGS__)
+ ##__VA_ARGS__); \
+} while (0)
/**
* KUNIT_FAIL() - Always causes a test to fail when evaluated.
@@ -637,6 +650,7 @@ void __kunit_do_failed_assertion(struct kunit *test,
fmt, \
...) \
do { \
+ _KUNIT_SAVE_LOC(test); \
if (likely(!!(condition_) == !!expected_true_)) \
break; \
\
@@ -698,6 +712,7 @@ do { \
.right_text = #right, \
}; \
\
+ _KUNIT_SAVE_LOC(test); \
if (likely(__left op __right)) \
break; \
\
@@ -758,6 +773,7 @@ do { \
.right_text = #right, \
}; \
\
+ _KUNIT_SAVE_LOC(test); \
if (likely((__left) && (__right) && (strcmp(__left, __right) op 0))) \
break; \
\
@@ -791,6 +807,7 @@ do { \
.right_text = #right, \
}; \
\
+ _KUNIT_SAVE_LOC(test); \
if (likely(__left && __right)) \
if (likely(memcmp(__left, __right, __size) op 0)) \
break; \
@@ -815,6 +832,7 @@ do { \
do { \
const typeof(ptr) __ptr = (ptr); \
\
+ _KUNIT_SAVE_LOC(test); \
if (!IS_ERR_OR_NULL(__ptr)) \
break; \
\
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index 7a3910dd78a6..d36e78095fdc 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -96,9 +96,13 @@ 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, "try faulted\n");
- else if (exit_code == -ETIMEDOUT)
+ else if (exit_code == -EINTR) {
+ if (test->last_seen.file)
+ kunit_err(test, "try faulted after %s:%d\n",
+ test->last_seen.file, test->last_seen.line);
+ else
+ kunit_err(test, "try faulted before the first test\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);
--
2.44.0
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.
Fix the -EINTR error message, which couldn't be reached until now.
This is tested with a following patch.
Cc: Brendan Higgins <[email protected]>
Cc: Shuah Khan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: David Gow <[email protected]>
Tested-by: Rae Moar <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
Changes since v2:
* s/-EFAULT/-EINTR/ in commit message as spotted by Rae.
* Add a comment explaining vfork_done as suggested by David.
* Add David's Reviewed-by.
* Add Rae's Tested-by.
Changes since v1:
* Add Kees's Reviewed-by.
---
include/kunit/try-catch.h | 3 ---
lib/kunit/try-catch.c | 19 ++++++++++++-------
2 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h
index c507dd43119d..7c966a1adbd3 100644
--- a/include/kunit/try-catch.h
+++ b/include/kunit/try-catch.h
@@ -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;
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index cab8b24b5d5a..7a3910dd78a6 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -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)
--
2.44.0
On Tue, 19 Mar 2024 at 18:49, Mickaël Salaün <[email protected]> wrote:
>
> 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.
>
> Fix the -EINTR error message, which couldn't be reached until now.
>
> This is tested with a following patch.
>
> Cc: Brendan Higgins <[email protected]>
> Cc: Shuah Khan <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Reviewed-by: David Gow <[email protected]>
> Tested-by: Rae Moar <[email protected]>
> Signed-off-by: Mickaël Salaün <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> ---
>
> Changes since v2:
> * s/-EFAULT/-EINTR/ in commit message as spotted by Rae.
> * Add a comment explaining vfork_done as suggested by David.
> * Add David's Reviewed-by.
> * Add Rae's Tested-by.
>
> Changes since v1:
> * Add Kees's Reviewed-by.
> ---
> include/kunit/try-catch.h | 3 ---
> lib/kunit/try-catch.c | 19 ++++++++++++-------
> 2 files changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h
> index c507dd43119d..7c966a1adbd3 100644
> --- a/include/kunit/try-catch.h
> +++ b/include/kunit/try-catch.h
> @@ -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;
> diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
> index cab8b24b5d5a..7a3910dd78a6 100644
> --- a/lib/kunit/try-catch.c
> +++ b/lib/kunit/try-catch.c
> @@ -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);
It turns out kthread_exit() is not exported, so this doesn't work if
KUnit is built as a module.
I think the options we have are:
- Add EXPORT_SYMBOL(kthread_exit).
- Keep using out own completion, and kthread_complete_and_exit()
- try_get_module() before spawning the thread, and use
module_put_and_kthread_exit().
I think all of these would be okay, but I could've missed something.
-- David
> }
> 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)
> --
> 2.44.0
>
On Sat, Mar 23, 2024 at 03:37:21PM +0800, David Gow wrote:
> On Tue, 19 Mar 2024 at 18:49, Mickaël Salaün <[email protected]> wrote:
> >
> > 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.
> >
> > Fix the -EINTR error message, which couldn't be reached until now.
> >
> > This is tested with a following patch.
> >
> > Cc: Brendan Higgins <[email protected]>
> > Cc: Shuah Khan <[email protected]>
> > Reviewed-by: Kees Cook <[email protected]>
> > Reviewed-by: David Gow <[email protected]>
> > Tested-by: Rae Moar <[email protected]>
> > Signed-off-by: Mickaël Salaün <[email protected]>
> > Link: https://lore.kernel.org/r/[email protected]
> > ---
> >
> > Changes since v2:
> > * s/-EFAULT/-EINTR/ in commit message as spotted by Rae.
> > * Add a comment explaining vfork_done as suggested by David.
> > * Add David's Reviewed-by.
> > * Add Rae's Tested-by.
> >
> > Changes since v1:
> > * Add Kees's Reviewed-by.
> > ---
> > include/kunit/try-catch.h | 3 ---
> > lib/kunit/try-catch.c | 19 ++++++++++++-------
> > 2 files changed, 12 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h
> > index c507dd43119d..7c966a1adbd3 100644
> > --- a/include/kunit/try-catch.h
> > +++ b/include/kunit/try-catch.h
> > @@ -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;
> > diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
> > index cab8b24b5d5a..7a3910dd78a6 100644
> > --- a/lib/kunit/try-catch.c
> > +++ b/lib/kunit/try-catch.c
> > @@ -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);
>
> It turns out kthread_exit() is not exported, so this doesn't work if
> KUnit is built as a module.
>
> I think the options we have are:
> - Add EXPORT_SYMBOL(kthread_exit).
I'll go this way. This should not be an issue because
kthread_complete_and_exit() can already (only) call kthread_exit() if
the completion is NULL, but directly calling kthread_exit() is cleaner.
> - Keep using out own completion, and kthread_complete_and_exit()
> - try_get_module() before spawning the thread, and use
> module_put_and_kthread_exit().
>
> I think all of these would be okay, but I could've missed something.
>
> -- David