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Richard Fitzgerald
fcbac39b7d
Swap the arguments to typecheck_fn() in kunit_activate_static_stub()
so that real_fn_addr can be either the function itself or a pointer
to that function.
This is useful to simplify redirecting static functions in a module.
Having to pass the actual function meant that it must be exported
from the module. Either making the 'static' and EXPORT_SYMBOL*()
conditional (which makes the code messy), or change it to always
exported (which increases the export namespace and prevents the
compiler inlining a trivial stub function in non-test builds).
With the original definition of kunit_activate_static_stub() the
address of real_fn_addr was passed to typecheck_fn() as the type to
be passed. This meant that if real_fn_addr was a pointer-to-function
it would resolve to a ** instead of a *, giving an error like this:
error: initialization of ‘int (**)(int)’ from incompatible pointer
type ‘int (*)(int)’ [-Werror=incompatible-pointer-types]
kunit_activate_static_stub(test, add_one_fn_ptr, subtract_one);
| ^~~~~~~~~~~~
./include/linux/typecheck.h:21:25: note: in definition of macro
‘typecheck_fn’
21 | ({ typeof(type) __tmp = function; \
Swapping the arguments to typecheck_fn makes it take the type of a
pointer to the replacement function. Either a function or a pointer
to function can be assigned to that. For example:
static int some_function(int x)
{
/* whatever */
}
int (* some_function_ptr)(int) = some_function;
static int replacement(int x)
{
/* whatever */
}
Then:
kunit_activate_static_stub(test, some_function, replacement);
yields:
typecheck_fn(typeof(&replacement), some_function);
and:
kunit_activate_static_stub(test, some_function_ptr, replacement);
yields:
typecheck_fn(typeof(&replacement), some_function_ptr);
The two typecheck_fn() then resolve to:
int (*__tmp)(int) = some_function;
and
int (*__tmp)(int) = some_function_ptr;
Both of these are valid. In the first case the compiler inserts
an implicit '&' to take the address of the supplied function, and
in the second case the RHS is already a pointer to the same type.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.