Re: [PATCH 10/10] ARM: FIQ: Get rid of init_FIQ()

Anton Vorontsov
2012-11-23T05:56:42Z

On Fri, Nov 23, 2012 at 07:40:30AM +0400, Alexander Shiyan wrote:
[...]
> > static unsigned long no_fiq_insn;
> > +static int got_no_fiq_insn;
> > @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec)
> >
> > void set_fiq_handler(void *start, unsigned int length)
> > {
> > -#if defined(CONFIG_CPU_USE_DOMAINS)
> > - memcpy((void *)0xffff001c, start, length);
> > -#else
> > - memcpy(vectors_page + 0x1c, start, length);
> > + unsigned long *addr = (void *)0xffff001c;
> > +
> > +#ifndef CONFIG_CPU_USE_DOMAINS
> > + addr = vectors_page + 0x1c;
> > #endif
> > + if (!cmpxchg(&got_no_fiq_insn, 0, 1))
> > + no_fiq_insn = *addr;
> > + memcpy(addr, start, length);
> > flush_icache_range(0xffff001c, 0xffff001c + length);
> > if (!vectors_high())
> > flush_icache_range(0x1c, 0x1c + length);
> > @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */
> > -
> > -void __init init_FIQ(void)
> > -{
> > - no_fiq_insn = *(unsigned long *)0xffff001c;
>
> it seems that this is wrong. In this case we have an uninitialized variable and
> sequential call claim_fiq and release_fiq could be fatal. FIXME please.

Um... I don't think I understand, can you please elaborate?

Thanks,
Anton.