Messages in this thread | | | Date | Fri, 5 Dec 2008 23:41:05 -0800 | From | Andrew Morton <> | Subject | Re: [RFC] Recursive printk |
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On Sat, 6 Dec 2008 08:33:05 +0100 Willy Tarreau <w@1wt.eu> wrote:
> On Fri, Dec 05, 2008 at 11:20:16PM -0800, Andrew Morton wrote: > > > void snd_verbose_printk(const char *file, int line, const char *format, ...) > > > { > > > va_list args; > > > > > > if (format[0] == '<' && format[1] >= '0' && format[1] <= '7' && format[2] == '>') { > > > char tmp[] = "<0>"; > > > tmp[1] = format[1]; > > > printk("%sALSA %s:%d: ", tmp, file, line); > > > format += 3; > > > > That's racy. Two threads can fight over tmp[1]. It should do: > > > > printk("<%c>ALSA %s:%d: ", format[1], tmp, file, line); > > > > (I didn't know that you can even modify literal strings - shouldn't > > they be in read-only storage?) > > no Andrew, this tmp[] is declared on the stack, and gcc emits code to > copy the constant "<0>" onto the stack every time this code is called
Good heavens, so it does. It is unusual for C to cater to such stupid code by generating such inefficient code. A bit of a trap, really.
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