On Tue, 4 Apr 2023 at 21:32, Maxime Ripard <maxime@xxxxxxxxxx> wrote: > > Hi David, > > Looks great, thanks for sending a second version > > On Fri, Mar 31, 2023 at 04:04:09PM +0800, David Gow wrote: > > Many uses of the KUnit resource system are intended to simply defer > > calling a function until the test exits (be it due to success or > > failure). The existing kunit_alloc_resource() function is often used for > > this, but was awkward to use (requiring passing NULL init functions, etc), > > and returned a resource without incrementing its reference count, which > > -- while okay for this use-case -- could cause problems in others. > > > > Instead, introduce a simple kunit_add_action() API: a simple function > > (returning nothing, accepting a single void* argument) can be scheduled > > to be called when the test exits. Deferred actions are called in the > > opposite order to that which they were registered. > > > > This mimics the devres API, devm_add_action(), and also provides > > kunit_remove_action(), to cancel a deferred action, and > > kunit_release_action() to trigger one early. > > > > This is implemented as a resource under the hood, so the ordering > > between resource cleanup and deferred functions is maintained. > > > > Signed-off-by: David Gow <davidgow@xxxxxxxxxx> > > --- > > > > Changes since RFC v1: > > https://lore.kernel.org/linux-kselftest/20230325043104.3761770-2-davidgow@xxxxxxxxxx/ > > - Rename functions to better match the devm_* APIs. (Thanks Maxime) > > - Embed the kunit_resource in struct kunit_action_ctx to avoid an extra > > allocation (Thanks Benjamin) > > - Use 'struct kunit_action_ctx' as the type for cancellation tokens > > (Thanks Benjamin) > > - Add tests. > > > > --- > > include/kunit/resource.h | 89 ++++++++++++++++++++++++++++ > > lib/kunit/kunit-test.c | 123 ++++++++++++++++++++++++++++++++++++++- > > lib/kunit/resource.c | 99 +++++++++++++++++++++++++++++++ > > 3 files changed, 310 insertions(+), 1 deletion(-) > > > > diff --git a/include/kunit/resource.h b/include/kunit/resource.h > > index c0d88b318e90..15efd8924666 100644 > > --- a/include/kunit/resource.h > > +++ b/include/kunit/resource.h > > @@ -387,4 +387,93 @@ static inline int kunit_destroy_named_resource(struct kunit *test, > > */ > > void kunit_remove_resource(struct kunit *test, struct kunit_resource *res); > > > > +typedef void (*kunit_defer_function_t)(void *ctx); > > + > > +/* An opaque token to a deferred action. */ > > +struct kunit_action_ctx; > > + > > +/** > > + * kunit_add_action() - Defer an 'action' (function call) until the test ends. > > + * @test: Test case to associate the action with. > > + * @func: The function to run on test exit > > + * @ctx: Data passed into @func > > + * @internal_gfp: gfp to use for internal allocations, if unsure, use GFP_KERNEL > > + * > > + * Defer the execution of a function until the test exits, either normally or > > + * due to a failure. @ctx is passed as additional context. All functions > > + * registered with kunit_add_action() will execute in the opposite order to that > > + * they were registered in. > > + * > > + * This is useful for cleaning up allocated memory and resources. > > + * > > + * Returns: > > + * An opaque "cancellation token", or NULL on error. Pass this token to > > + * kunit_remove_action_token() in order to cancel the deferred execution of > > + * func(). > > + */ > > +struct kunit_action_ctx *kunit_add_action(struct kunit *test, kunit_defer_function_t func, > > + void *ctx, gfp_t internal_gfp); > > Do we expect any other context than GFP_KERNEL? > > If so, then maybe we can have kunit_add_action() assume GFP_KERNEL and > add a variant for the odd case where we would actually need a different > GFP flag. > That'd be fine. The only cases which don't directly pass GFP_KERNEL in are in the kunit_kmalloc() functions, which themselves accept a gfp to pass down to kmalloc(). We didn't want to add an extra GFP_KERNEL allocation there. This definitely could be relegated to a separate variant of the function, though (or we could keep using the old implementation of kunit_kmalloc_array() which creates resources manually). Trying to match the devm_add_action() API, which assumed GFP_KERNEL probably makes sense... > > +/** > > + * kunit_remove_action_token() - Cancel a deferred action. > > + * @test: Test case the action is associated with. > > + * @cancel_token: The cancellation token returned by kunit_add_action() > > + * > > + * Prevent an action deferred using kunit_add_action() from executing when the > > + * test ends. > > + * > > + * You can also use the (test, function, context) triplet to remove an action > > + * with kunit_remove_action(). > > + */ > > +void kunit_remove_action_token(struct kunit *test, struct kunit_action_ctx *cancel_token); > > It's not clear to me why we still need the token. If > kunit_remove_action() works fine, why would we need to store the token? > > Can't we just make kunit_add_action() return an int to indicate whether > it failed or not, and that's it? > So the distinction here is that the (function, context) pair doesn't uniquely identify an action, as you can add the same action multiple times, with other actions interleaved. A token encodes _which_ of these actions is being triggered/cancelled: the non-token variants always cancel the most recent matching function. Without the token, there's no way of removing an action "further down the stack". Take, for example, two functions, add_one() and double(), which are (*ctx)++ and (*ctx) *= 2, respectively. int var = 0; tok1 = kunit_add_action(test, add_one, &var); kunit_add_action(test, double, &var); tok3 = kunit_add_action(test, add_one, &var); // The call: kunit_remove_action(test, add_one, &var); // is equivalent to kunit_remove_action_token(test, tok3); // and gives var = 1 as a final result // If instead we want to remove the first add_one, we use: kunit_remove_action_token(test, tok1); // which cannot be done using kunit_remove_action() // gives var = 2 instead. There's also a (minor) performance benefit to using the token versions, as we don't need to do a (currently O(n)) search through the list of KUnit resources to find the matching entry. I doubt too many tests will defer enough to make this a problem. That being said, given no-one actually needs this behaviour yet, it's definitely something we could add later if it becomes necessary. I doubt it'd be useful for most of the normal resource management use-cases. > > +/** > > + * kunit_release_action_token() - Trigger a deferred action immediately. > > + * @test: Test case the action is associated with. > > + * @cancel_token: The cancellation token returned by kunit_add_action() > > + * > > + * Execute an action immediately, instead of waiting for the test to end. > > + * > > + * You can also use the (test, function, context) triplet to trigger an action > > + * with kunit_release_action(). > > + */ > > +void kunit_release_action_token(struct kunit *test, struct kunit_action_ctx *cancel_token); > > + > > +/** > > + * kunit_remove_action() - Cancel a matching deferred action. > > + * @test: Test case the action is associated with. > > + * @func: The deferred function to cancel. > > + * @ctx: The context passed to the deferred function to trigger. > > + * > > + * Prevent an action deferred via kunit_add_action() from executing when the > > + * test terminates.. > > + * Unlike kunit_remove_action_token(), this takes the (func, ctx) pair instead of > > + * the cancellation token. If that function/context pair was deferred multiple > > + * times, only the most recent one will be cancelled. > > + */ > > +void kunit_remove_action(struct kunit *test, > > + kunit_defer_function_t func, > > + void *ctx); > > + > > +/** > > + * kunit_release_action() - Run a matching action call immediately. > > + * @test: Test case the action is associated with. > > + * @func: The deferred function to trigger. > > + * @ctx: The context passed to the deferred function to trigger. > > + * > > + * Execute a function deferred via kunit_add_action()) immediately, rather than > > + * when the test ends. > > + * Unlike kunit_release_action_token(), this takes the (func, ctx) pair instead of > > + * the cancellation token. If that function/context pair was deferred multiple > > + * times, it will only be executed once here. The most recent deferral will > > + * no longer execute when the test ends. > > + * > > + * kunit_release_action(test, func, ctx); > > + * is equivalent to > > + * func(ctx); > > + * kunit_remove_action(test, func, ctx); > > + */ > > +void kunit_release_action(struct kunit *test, > > + kunit_defer_function_t func, > > + void *ctx); > > #endif /* _KUNIT_RESOURCE_H */ > > diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c > > index b63595d3e241..eaca1b133922 100644 > > --- a/lib/kunit/kunit-test.c > > +++ b/lib/kunit/kunit-test.c > > @@ -111,7 +111,7 @@ struct kunit_test_resource_context { > > struct kunit test; > > bool is_resource_initialized; > > int allocate_order[2]; > > - int free_order[2]; > > + int free_order[4]; > > }; > > > > static int fake_resource_init(struct kunit_resource *res, void *context) > > @@ -402,6 +402,123 @@ static void kunit_resource_test_named(struct kunit *test) > > KUNIT_EXPECT_TRUE(test, list_empty(&test->resources)); > > } > > > > +static void increment_int(void *ctx) > > +{ > > + int *i = (int *)ctx; > > + (*i)++; > > +} > > + > > +static void kunit_resource_test_action(struct kunit *test) > > +{ > > + int num_actions = 0; > > + > > + kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + KUNIT_EXPECT_EQ(test, num_actions, 0); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 1); > > + > > + /* Once we've cleaned up, the action queue is empty. */ > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 1); > > + > > + /* Check the same function can be deferred multiple times. */ > > + kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 3); > > +} > > +static void kunit_resource_test_remove_action(struct kunit *test) > > +{ > > + int num_actions = 0; > > + struct kunit_action_ctx *cancel_token; > > + struct kunit_action_ctx *cancel_token2; > > + > > + cancel_token = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + KUNIT_EXPECT_EQ(test, num_actions, 0); > > + > > + kunit_remove_action_token(test, cancel_token); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 0); > > + > > + /* Check calls from the same function/context pair can be cancelled independently*/ > > + cancel_token = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + cancel_token2 = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_remove_action_token(test, cancel_token); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 1); > > + > > + /* Also check that we can cancel just one of the identical function/context pairs. */ > > + cancel_token = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + cancel_token2 = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_remove_action(test, increment_int, &num_actions); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 2); > > +} > > +static void kunit_resource_test_release_action(struct kunit *test) > > +{ > > + int num_actions = 0; > > + struct kunit_action_ctx *cancel_token; > > + struct kunit_action_ctx *cancel_token2; > > + > > + cancel_token = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + KUNIT_EXPECT_EQ(test, num_actions, 0); > > + /* Runs immediately on trigger. */ > > + kunit_release_action_token(test, cancel_token); > > + KUNIT_EXPECT_EQ(test, num_actions, 1); > > + > > + /* Doesn't run again on test exit. */ > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 1); > > + > > + /* Check calls from the same function/context pair can be triggered independently*/ > > + cancel_token = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + cancel_token2 = kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_release_action_token(test, cancel_token); > > + KUNIT_EXPECT_EQ(test, num_actions, 2); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 3); > > + > > + /* Also check that we can trigger just one of the identical function/context pairs. */ > > + kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_add_action(test, increment_int, &num_actions, GFP_KERNEL); > > + kunit_release_action(test, increment_int, &num_actions); > > + KUNIT_EXPECT_EQ(test, num_actions, 4); > > + kunit_cleanup(test); > > + KUNIT_EXPECT_EQ(test, num_actions, 5); > > +} > > +static void action_order_1(void *ctx) > > +{ > > + struct kunit_test_resource_context *res_ctx = (struct kunit_test_resource_context *)ctx; > > + > > + KUNIT_RESOURCE_TEST_MARK_ORDER(res_ctx, free_order, 1); > > + kunit_log(KERN_INFO, current->kunit_test, "action_order_1"); > > +} > > +static void action_order_2(void *ctx) > > +{ > > + struct kunit_test_resource_context *res_ctx = (struct kunit_test_resource_context *)ctx; > > + > > + KUNIT_RESOURCE_TEST_MARK_ORDER(res_ctx, free_order, 2); > > + kunit_log(KERN_INFO, current->kunit_test, "action_order_2"); > > +} > > +static void kunit_resource_test_action_ordering(struct kunit *test) > > +{ > > + struct kunit_test_resource_context *ctx = test->priv; > > + struct kunit_action_ctx *cancel_token; > > + > > + kunit_add_action(test, action_order_1, ctx, GFP_KERNEL); > > + cancel_token = kunit_add_action(test, action_order_2, ctx, GFP_KERNEL); > > + kunit_add_action(test, action_order_1, ctx, GFP_KERNEL); > > + kunit_add_action(test, action_order_2, ctx, GFP_KERNEL); > > + kunit_remove_action(test, action_order_1, ctx); > > + kunit_release_action_token(test, cancel_token); > > + kunit_cleanup(test); > > + > > + /* [2 is triggered] [2], [(1 is cancelled)] [1] */ > > + KUNIT_EXPECT_EQ(test, ctx->free_order[0], 2); > > + KUNIT_EXPECT_EQ(test, ctx->free_order[1], 2); > > + KUNIT_EXPECT_EQ(test, ctx->free_order[2], 1); > > +} > > + > > static int kunit_resource_test_init(struct kunit *test) > > { > > struct kunit_test_resource_context *ctx = > > @@ -433,6 +550,10 @@ static struct kunit_case kunit_resource_test_cases[] = { > > KUNIT_CASE(kunit_resource_test_proper_free_ordering), > > KUNIT_CASE(kunit_resource_test_static), > > KUNIT_CASE(kunit_resource_test_named), > > + KUNIT_CASE(kunit_resource_test_action), > > + KUNIT_CASE(kunit_resource_test_remove_action), > > + KUNIT_CASE(kunit_resource_test_release_action), > > + KUNIT_CASE(kunit_resource_test_action_ordering), > > {} > > }; > > > > diff --git a/lib/kunit/resource.c b/lib/kunit/resource.c > > index c414df922f34..824cf91e306d 100644 > > --- a/lib/kunit/resource.c > > +++ b/lib/kunit/resource.c > > @@ -77,3 +77,102 @@ int kunit_destroy_resource(struct kunit *test, kunit_resource_match_t match, > > return 0; > > } > > EXPORT_SYMBOL_GPL(kunit_destroy_resource); > > + > > +struct kunit_action_ctx { > > + struct kunit_resource res; > > + kunit_defer_function_t func; > > + void *ctx; > > +}; > > + > > +static void __kunit_action_free(struct kunit_resource *res) > > +{ > > + struct kunit_action_ctx *action_ctx = container_of(res, struct kunit_action_ctx, res); > > + > > + action_ctx->func(action_ctx->ctx); > > +} > > + > > +struct kunit_action_ctx *kunit_add_action(struct kunit *test, kunit_defer_function_t func, > > + void *ctx, gfp_t internal_gfp) > > +{ > > + struct kunit_action_ctx *action_ctx; > > + > > + KUNIT_ASSERT_NOT_NULL_MSG(test, func, "Tried to action a NULL function!"); > > + > > + action_ctx = kzalloc(sizeof(*action_ctx), internal_gfp); > > + if (!action_ctx) > > + return NULL; > > + > > + action_ctx->func = func; > > + action_ctx->ctx = ctx; > > + > > + action_ctx->res.should_kfree = true; > > + /* As init is NULL, this cannot fail. */ > > + __kunit_add_resource(test, NULL, __kunit_action_free, &action_ctx->res, action_ctx); > > + > > + return action_ctx; > > +} > > One thing worth pointing is that if kunit_add_action() fails, the > cleanup function passed as an argument won't run. > > So, if the kzalloc call ever fails, patch 2 will leak its res->data() > resource for example. > > devm (and drmm) handles this using a variant called > devm_add_action_or_reset, we should either provide the same variant or > just go for that behavior by default. > Excellent point. I think I'll add a kunit_add_action_or_reset() variant to the next revision. If we've gone this far to match the devm_ API, continuing to do so probably is the best way of handling it. Cheers, -- David
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