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Date: Sat, 15 Mar 2003 13:09:33 -0800 (PST)
Subject: bitmaps/bitops
From: "Randy.Dunlap" <rddunlap@osdl.org>
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Hi,

Not picking on this code, but as an example:

drivers/ieee1394/ieee1394_transactions.c, line 152 (in 2.5.64),
uses:  test_and_set_bit(bit_number, tp->pool),

where tp->pool is declared by using a DECLARE_BITMAP(), like so:
struct hpsb_tlabel_pool {
	DECLARE_BITMAP(pool, 64);

That makes sense (at least to me), but gcc complains about the
type of <pool> when used in test_and_set_bit():
  drivers/ieee1394/ieee1394_transactions.c:152: warning: passing arg 2 of
`test_and_set_bit' from incompatible pointer type

Is this an error, a bug, a nuisance, or just another "ignore gcc 2.96"
problem?

For reference, DECLARE_BITMAP() generates an array of unsigned longs:
#define DECLARE_BITMAP(name,bits) \
	unsigned long name[BITS_TO_LONGS(bits)]
but the prototype for test_and_set_bit() depends on $(ARCH), and it's
not consistent, with the second arg (bitmap address) being one of:
  volatile void *
  void *
  volatile unsigned long *


If there's (kernel) surgery required here, unless it's trivial, I think
that I'd leave it for early 2.7.

~Randy