kunit_kfree() exists to clean up allocations from kunit_kmalloc() and
friends early instead of waiting for this to happen automatically at the
end of the test.
But it can be used on *anything* registered with the kunit resource API.
E.g. the last 2 statements are equivalent:
struct kunit_resource *res = something();
kfree(res->data);
kunit_put_resource(res);
The problem is that there could be multiple resources that point to the
same `data`.
E.g. you can have a named resource acting as a pseudo-global variable in
a test. If you point it to data allocated with kunit_kmalloc(), then
calling `kunit_kfree(ptr)` has the chance to delete either the named
resource or to kfree `ptr`.
Which one it does depends on the order the resources are registered as
kunit_kfree() will delete resources in LIFO order.
So this patch restricts kunit_kfree() to only working on resources
created by kunit_kmalloc(). Calling it is therefore guaranteed to free
the memory, not do anything else.
Note: kunit_resource_instance_match() wasn't used outside of KUnit, so
it should be safe to remove from the public interface. It's also
generally dangerous, as shown above, and shouldn't be used.
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
KUnit's test-managed resources can be created in two ways:
- Using the kunit_add_resource() family of functions, which accept a
struct kunit_resource pointer, typically allocated statically or on
the stack during the test.
- Using the kunit_alloc_resource() family of functions, which allocate a
struct kunit_resource using kzalloc() behind the scenes.
Both of these families of functions accept a 'free' function to be
called when the resource is finally disposed of.
At present, KUnit will kfree() the resource if this 'free' function is
specified, and will not if it is NULL. However, this can lead
kunit_alloc_resource() to leak memory (if no 'free' function is passed
in), or kunit_add_resource() to incorrectly kfree() memory which was
allocated by some other means (on the stack, as part of a larger
allocation, etc), if a 'free' function is provided.
Instead, always kfree() if the resource was allocated with
kunit_alloc_resource(), and never kfree() if it was passed into
kunit_add_resource() by the user. (If the user of kunit_add_resource()
wishes the resource be kfree()ed, they can call kfree() on the resource
from within the 'free' function.
This is implemented by adding a 'should_free' member to
struct kunit_resource and setting it appropriately. To facilitate this,
the various resource add/alloc functions have been refactored somewhat,
making them all call a __kunit_add_resource() helper after setting the
'should_free' member appropriately. In the process, all other functions
have been made static inline functions.
Signed-off-by: David Gow <davidgow@google.com>
Tested-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Background:
Currently, a reader looking at kunit/test.h will find the file is quite
long, and the first meaty comment is a doc comment about struct
kunit_resource.
Most users will not ever use the KUnit resource API directly.
They'll use kunit_kmalloc() and friends, or decide it's simpler to do
cleanups via labels (it often can be) instead of figuring out how to use
the API.
It's also logically separate from everything else in test.h.
Removing it from the file doesn't cause any compilation errors (since
struct kunit has `struct list_head resources` to store them).
This commit:
Let's move it into a kunit/resource.h file and give it a separate page
in the docs, kunit/api/resource.rst.
We include resource.h at the bottom of test.h since
* don't want to force existing users to add a new include if they use the API
* it accesses `lock` inside `struct kunit` in a inline func
* so we can't just forward declare, and the alternatives require
uninlining the func, adding hepers to lock/unlock, or other more
invasive changes.
Now the first big comment in test.h is about kunit_case, which is a lot
more relevant to what a new user wants to know.
A side effect of this is git blame won't properly track history by
default, users need to run
$ git blame -L ,1 -C17 include/kunit/resource.h
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
