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    SubjectRe: [RFC] Recursive printk
    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
    (which is basically just a 32-bit integer copy). So there's no race
    either.

    Regards,
    Willy



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