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authorPeter Zijlstra <peterz@infradead.org>2013-11-20 16:52:19 +0100
committerIngo Molnar <mingo@kernel.org>2014-01-13 13:47:37 +0100
commit62b94a08da1bae9d187d49dfcd6665af393750f8 (patch)
treec3e66c87005da3aa35e367523ee869d5c3902e70
parent9ea4c380066fbe23fe0da7f4abfabc444f2467f4 (diff)
downloadop-kernel-dev-62b94a08da1bae9d187d49dfcd6665af393750f8.zip
op-kernel-dev-62b94a08da1bae9d187d49dfcd6665af393750f8.tar.gz
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 <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com> Cc: rui.zhang@intel.com Cc: jacob.jun.pan@linux.intel.com Cc: Mike Galbraith <bitbucket@online.de> Cc: hpa@zytor.com Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: lenb@kernel.org Cc: rjw@rjwysocki.net Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-fn7h6vu8wtgxk0ih402qcijx@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--include/linux/preempt.h22
-rw-r--r--include/linux/uaccess.h5
2 files changed, 24 insertions, 3 deletions
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index a3d9dc8..dd9ddf8 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 9d8cf05..ecd3319 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
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