On Sun, Aug 26, 2018 at 11:35:17PM -0400, Julia Lawall wrote:

* x = \(kmalloc\|kzalloc\|devm_kmalloc\|devm_kzalloc\)(...)

I can name several you've missed right off the top of my head -
vmalloc, kvmalloc, kmem_cache_alloc, kmem_cache_zalloc, variants
with _trace slapped on, and that is not to mention the things like
get_free_page or

void *my_k3wl_alloc(u64 n) // 'cause all artificial limits suck, that's why
{
	lots and lots of home-grown stats collection
	some tracepoints thrown in just for fun
	return kmalloc(n);
}

(and no, I'm not implying that net/sched folks had done anything of that
sort; I have seen that and worse in drivers, though)

The * at the beginning of the line means to highlight what you are looking
for, which is done by making a diff in which the highlighted line
appears to be removed.

Umm...  Does that cover return, BTW?  Or something like
	T *barf;
	extern void foo(T *p);
	foo(kmalloc(sizeof(*barf)));

The limitation is the ability to figure out the type of x.  If it is a
local variable, Coccinelle should have no problem.  If it is a structure
field, it may be necessary to provide command line arguments like

--all-includes --include-headers-for-types

--all-includes means to try to find all include files that are mentioned
in the .c file.  The next stronger option is --recursive includes, which
means include what all of the mentioned files include as well,
recursively.  This tends to cause a major performance hit, because a lot
of code is being parsed.  --include-headers-for-types heals a bit with
that, as it only considers the header files when computing type
information, and now when applying the rules.

With respect to ifdefs around variable declarations and structure field
declaration, in these cases Coccinelle considers that it cannot make the
ifdef have an if-like control flow, and so if considers the #ifdef, #else
and #endif to be comments.  Thus it takes into account only the last type
provided for a given variable.

[snip]

What about several variants of structure definition?  Because ifdefs around
includes do occur in the wild...