On Wed, 20 Nov 2013 17:04:57 +0100 Peter Zijlstra <[email protected]> wrote:
> Discourage drivers/modules to be creative with preemption. > > Sadly all is implemented in macros and inline so if they want to do > evil they still can, but at least try and discourage some. > > Cc: Rusty Russell <[email protected]> > Cc: Arjan van de Ven <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: Eliezer Tamir <[email protected]> > Cc: Chris Leech <[email protected]> > Cc: David S. Miller <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: Mike Galbraith <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: [email protected] > Reviewed-by: Thomas Gleixner <[email protected]> > Signed-off-by: Peter Zijlstra <[email protected]> > --- > include/linux/preempt.h | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > --- a/include/linux/preempt.h > +++ b/include/linux/preempt.h > @@ -64,7 +64,11 @@ do { \ > } while (0) > > #else > -#define preempt_enable() preempt_enable_no_resched() > +#define preempt_enable() \ > +do { \ > + barrier(); \ > + preempt_count_dec(); \ > +} while (0) > #define preempt_check_resched() do { } while (0) > #endif > > @@ -126,6 +130,16 @@ do { \ > #define preempt_fold_need_resched() do { } while (0) > #endif > > +#ifdef MODULE > +/* > + * Modules have no business playing preemption tricks. > + */ > +#undef sched_preempt_enable_no_resched > +#undef preempt_enable_no_resched > +#undef preempt_enable_no_resched_notrace > +#undef preempt_check_resched > +#endif > + > #ifdef CONFIG_PREEMPT_NOTIFIERS > > struct preempt_notifier; > > run into a couple of compile issues. 1) include/linux/rcupdate.h: In function ‘rcu_read_unlock_sched_notrace’: include/linux/rcupdate.h:889:2: error: implicit declaration of function ‘preempt_enable_no_resched_notrace’ [-Werror=implicit-function-declaration] 2) In file included from drivers/cpufreq/acpi-cpufreq.c:41:0: include/linux/uaccess.h: In function ‘pagefault_enable’: include/linux/uaccess.h:34:2: error: implicit declaration of function ‘preempt_check_resched’ [-Werror=implicit-function-declaration] 1) happens when CONFIG_PREEMPT is not set, perhaps add a dummy function? 2) I am not sure if we should take pagefault_enable away from modules -- 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/
