From 62b94a08da1bae9d187d49dfcd6665af393750f8 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 20 Nov 2013 16:52:19 +0100 Subject: [PATCH] sched/preempt: Take away preempt_enable_no_resched() from modules 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. Reviewed-by: Thomas Gleixner Signed-off-by: Peter Zijlstra Cc: Eliezer Tamir Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith Cc: hpa@zytor.com Cc: Rusty Russell Cc: Arjan van de Ven Cc: lenb@kernel.org Cc: rjw@rjwysocki.net Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/n/tip-fn7h6vu8wtgxk0ih402qcijx@git.kernel.org Signed-off-by: Ingo Molnar --- include/linux/preempt.h | 22 ++++++++++++++++++++-- include/linux/uaccess.h | 5 ++++- 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/include/linux/preempt.h b/include/linux/preempt.h index a3d9dc8c2c0..dd9ddf8af20 100644 --- 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 @@ -93,7 +97,11 @@ do { \ __preempt_schedule_context(); \ } while (0) #else -#define preempt_enable_notrace() preempt_enable_no_resched_notrace() +#define preempt_enable_notrace() \ +do { \ + barrier(); \ + __preempt_count_dec(); \ +} while (0) #endif #else /* !CONFIG_PREEMPT_COUNT */ @@ -116,6 +124,16 @@ do { \ #endif /* CONFIG_PREEMPT_COUNT */ +#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; diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 9d8cf056e66..ecd3319dac3 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -25,13 +25,16 @@ static inline void pagefault_disable(void) static inline void pagefault_enable(void) { +#ifndef CONFIG_PREEMPT /* * make sure to issue those last loads/stores before enabling * the pagefault handler again. */ barrier(); preempt_count_dec(); - preempt_check_resched(); +#else + preempt_enable(); +#endif } #ifndef ARCH_HAS_NOCACHE_UACCESS -- 2.43.2