Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1290005

Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode

Show all headers | View raw

On Fri, Dec 11, 2015 at 08:49:24AM +0100, Rasmus Villemoes wrote:

> union delayed_call_fn {
> 	void (*fn)(void *);
> 	void (*kfree_like)(const void *);
> } __attribute__((__transparent_union__));
>
> void
> set_delayed_call(struct delayed_call *call, union delayed_call_fn u, void *arg)
> {
> 	call->fn = u.fn;
> 	call->arg = arg;
> }

	Yecchhhh...  If we are into that kind of gccisms, I'd rather use
__builtin_choose_expr/__builtin_types_compatible_p.  At least that is
used elsewhere in the kernel; __transparent_union__ kludge isn't.  Sure, it
means having set_delayed_call() a macro, but IMO it's less nasty that way...

	FWIW, another possibility is to have
#define CLOSURE_CALLBACK(f,type) \
	static inline void __closure_##f(void *p) {return f((type)p);}

#define set_delayed_type(call, f, arg) \
	sizeof(f(arg),0), \
	__set_delayed_type(call, __closure_##f, (void *)arg)

That could be reused for timers with typechecking - we have a lot of timer
callbacks that start with casting the argument (unsigned long, not void *,
but that's not a big deal) to whatever it is that callback really wants,
with setup_timer() callers explicitly casting that whatever the callback
really wants to unsigned long.  Which, of course, defeats the typechecking
by both cc(1) and sparse(1)...

I still hope for better solution, though...  Comments?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 02/11] logfs: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 08/11] teach page_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 10/11] teach proc_self_get_link()/proc_thread_self_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 11/11] teach nfs_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 06/11] don't put symlink bodies in pagecache into highmem Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 01/11] switch befs long symlinks to page_symlink_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 03/11] udf: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 09/11] teach shmem_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 04/11] ufs: get rid of ->setattr() for symlinks Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-09 18:30 +0100
    Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 19:30 +0100
      Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-10 01:20 +0100
        Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-10 03:50 +0100
          Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-12-11 08:50 +0100
            Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-12 00:20 +0100
              Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-12 03:10 +0100
                Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-12-13 19:50 +0100
          Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-13 04:50 +0100
  Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode NeilBrown <neilb@suse.com> - 2015-12-09 23:00 +0100

csiph-web