On Fri, 14 Feb 2014 14:18:46 -0600 Christoph Lameter <[email protected]> wrote:
> [Patch depends on another patch in this series that introduces raw_cpu_ops]
>
> We define a check function in order to avoid trouble with the
> include files. Then the higher level __this_cpu macros are
> modified to invoke the preemption check.
>
> --- linux.orig/lib/smp_processor_id.c 2014-01-30 14:40:50.936519233 -0600
> +++ linux/lib/smp_processor_id.c 2014-01-30 14:40:50.936519233 -0600
> @@ -7,7 +7,7 @@
> #include <linux/kallsyms.h>
> #include <linux/sched.h>
>
> -notrace unsigned int debug_smp_processor_id(void)
> +notrace static unsigned int check_preemption_disabled(char *what)
> {
> int this_cpu = raw_smp_processor_id();
>
> @@ -38,9 +38,9 @@
> if (!printk_ratelimit())
> goto out_enable;
>
> - printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] "
> - "code: %s/%d\n",
> - preempt_count() - 1, current->comm, current->pid);
> + printk(KERN_ERR "BUG: using %s in preemptible [%08x] code: %s/%d\n",
> + what, preempt_count() - 1, current->comm, current->pid);
> +
> print_symbol("caller is %s\n", (long)__builtin_return_address(0));
> dump_stack();
I wonder if there's any point in printing __builtin_return_address.
Doesn't dump_stack() tell us the same thing?
> @@ -50,5 +50,17 @@
> return this_cpu;
> }
>
> +notrace unsigned int debug_smp_processor_id(void)
> +{
> + return check_preemption_disabled("smp_processor_id()");
> +}
> EXPORT_SYMBOL(debug_smp_processor_id);
>
> +notrace void __this_cpu_preempt_check(const char *op)
> +{
> + char text[40];
> +
> + snprintf(text, sizeof(text), "__this_cpu_%s()", op);
> + check_preemption_disabled(text);
> +}
I'd like to see a comment here telling scared readers why this can
never overflow text[].
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
