From: Joe Perches <joe@perches.com>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
Karsten Keil <isdn@linux-pingi.de>,
"David S. Miller" <davem@davemloft.net>,
Masanari Iida <standby24x7@gmail.com>,
netdev@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] isdn: fix a wrapping bug in isdn_ppp_ioctl()
Date: Wed, 10 Oct 2012 06:00:07 -0700 [thread overview]
Message-ID: <1349874007.2386.42.camel@joe-AO722> (raw)
In-Reply-To: <m21uh67csy.fsf@igel.home>
On Wed, 2012-10-10 at 14:05 +0200, Andreas Schwab wrote:
> Joe Perches <joe@perches.com> 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-}
next prev parent reply other threads:[~2012-10-10 13:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 9:42 [patch] isdn: fix a wrapping bug in isdn_ppp_ioctl() Dan Carpenter
2012-10-10 10:19 ` Joe Perches
2012-10-10 10:41 ` Joe Perches
2012-10-10 10:42 ` David Laight
2012-10-10 11:15 ` Joe Perches
2012-10-10 12:05 ` Andreas Schwab
2012-10-10 13:00 ` Joe Perches [this message]
2012-10-10 13:58 ` Andreas Schwab
2012-10-10 14:41 ` Joe Perches
2012-10-10 14:59 ` David Laight
2012-10-10 15:19 ` Joe Perches
2012-10-10 15:44 ` David Laight
2012-10-10 15:52 ` Joe Perches
2012-10-12 7:49 ` Karsten Keil
2012-10-11 2:46 ` David Miller
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