GCC nested functions?

From: Stephen Hemminger
Date: Wed May 12 2004 - 13:02:26 EST

I used GCC nested functions in the (not released) bridge sysfs interface for 2.6.6.
It seemed like a nice way to express the sysfs related interface without doing
lots of code copying (or worse lots of macros).

The code in question looks like:
static ssize_t store_bridge_parm(struct class_device *cd,
const char *buf, size_t len,
void (*store)(struct net_bridge *, unsigned long))
struct net_bridge *br = to_bridge(cd);
char *endp;
unsigned long val;

if (!capable(CAP_NET_ADMIN))
return -EPERM;

val = simple_strtoul(buf, &endp, 0);
if (endp == buf)
return -EINVAL;

store(br, val);
return len;

static ssize_t store_forward_delay(struct class_device *cd, const char *buf,
size_t len)
void store(struct net_bridge *br, unsigned long val)
unsigned long delay = clock_t_to_jiffies(val);
br->forward_delay = delay;
if (br_is_root_bridge(br))
br->bridge_forward_delay = delay;

return store_bridge_parm(cd, buf, len, store);

This works fine for GCC 2.95 and 3.X for i386 and x86_64 architectures, but the ia64
(cross compiler) pukes with:

In function `store_forward_delay':
: undefined reference to `__ia64_trampoline'

Redoing it as separate functions is easy enough, but the questions are:
- Are gcc nested functions allowed in the kernel? If not where should
this restriction be put in Documentation? CodingStyles?
- Or is gcc on ia64 just too stupid? or do some more support routines
need to exist in arch/ia64?
- Do other architectures (sparc, ppc) have similar problems?


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