On Wed, 2012-10-10 at 14:05 +0200, Andreas Schwab wrote:
> Joe Perches <joe@xxxxxxxxxxx> writes:
>
> > @@ -589,16 +589,15 @@ isdn_ppp_ioctl(int min, struct file *file, unsigned int cmd, unsigned long arg)
> > break;
> > case PPPIOCGCOMPRESSORS:
> > {
> > - unsigned long protos[8] = {0,};
> > + DECLARE_BITMAP(protos, BITS_PER_LONG * 8) = { 0, };
> > struct isdn_ppp_compressor *ipc = ipc_head;
> > +
> > while (ipc) {
> > - j = ipc->num / (sizeof(long) * 8);
> > - i = ipc->num % (sizeof(long) * 8);
> > - if (j < 8)
> > - protos[j] |= (0x1 << i);
> > + if (ipc->num < BITS_PER_LONG * 8)
> > + set_bit(ipc->num, protos);
> > ipc = ipc->next;
> > }
> > - if ((r = set_arg(argp, protos, 8 * sizeof(long))))
> > + if ((r = set_arg(argp, protos, sizeof(protos))))
>
> This changes the bit endianess.
How does it do that?
include/linux/bitops.h:#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
include/linux/bitops.h:#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
include/asm-generic/bitops/atomic.h:static inline void set_bit(int nr, volatile unsigned long *addr)
include/asm-generic/bitops/atomic.h-{
include/asm-generic/bitops/atomic.h- unsigned long mask = BIT_MASK(nr);
include/asm-generic/bitops/atomic.h- unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
include/asm-generic/bitops/atomic.h- unsigned long flags;
include/asm-generic/bitops/atomic.h-
include/asm-generic/bitops/atomic.h- _atomic_spin_lock_irqsave(p, flags);
include/asm-generic/bitops/atomic.h- *p |= mask;
include/asm-generic/bitops/atomic.h- _atomic_spin_unlock_irqrestore(p, flags);
include/asm-generic/bitops/atomic.h-}
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