linux-kernel - reference counting gcc plugin

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Message-ID: <77f98dae-815f-2191-0a1d-63e2a0886d9e@gmail.com>
Date:   Sat, 17 Jun 2023 18:02:24 -0400
From:   Aravind Ceyardass <aravind.pub@...il.com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org
Subject: reference counting gcc plugin

2nd attempt. I hope this is the right mailing list. :-)

Hello Kernel People,

I have developed a gcc plugin for implementing reference counting. I see that the kernel has implemented many different techniques over the years, but I couldn't find any with compiler support.

I would like your ideas, inputs before I release the plugin for everyone hoping that it would benefit the Linux kernel.

Here is a sample code to give you an idea of usage and the code transformation done by the plugin.

#include "hrcmm.h"
/*
  REFTRACK_STRUCT macro defines the following declarations

  struct foo;
  void foo_addref(const struct foo *const);
  void foo_removeref(const struct foo *const);
  void foo_destroy(struct foo *const);
*/

REFTRACK_STRUCT(foo){
    int bar;
};

/*
  REFTRACK_EPILOG_WITH_DTOR macro calls foo_destroy when reference count is zero.
  This is optional, if there is no special cleanup to be done, use REFTRACK_EPILOG. 
*/
REFTRACK_EPILOG_WITH_DTOR(foo);

// This function is called when the reference count for object pointed to by p is zero
void foo_destroy(struct foo *p){
    if (p)
        printf("foo destroyed:%p\n", p);
}

typedef struct foo foo;

// statements commented out are injected by the plugin

void baz(foo *p){
    printf("%d\n", p->bar);
    // foo_removeref(p);
}

int main(int argc, char *argv[]){
    foo *p = rc_malloc(sizeof(foo)); // rc_malloc is a default wrapper provided
    // foo_addref(p); 
    p->bar = 123;

    // foo_addref(p); 
    foo *q = p;

    // foo_addref(q); 
    baz(q);

    // foo_removeref(p); 
    // foo_removeref(q); 
}

Aravind