resource: add helpers for fetching rlimits

commit 3e10e716abf3c71bdb5d86b8f507f9e72236c9cd upstream.

We want to be sure that compiler fetches the limit variable only
once, so add helpers for fetching current and maximal resource
limits which do that.

Add them to sched.h (instead of resource.h) due to circular dependency
 sched.h->resource.h->task_struct
Alternative would be to create a separate res_access.h or similar.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: James Morris <jmorris@namei.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d3e910b36c727bb15fd7b1554d5e7d84aaf2a4fa..338733b03c8fd0691e98b84d6da817c33abb2ca1 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2485,6 +2485,28 @@ static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
 
 #define TASK_STATE_TO_CHAR_STR "RSDTtZX"
 
+static inline unsigned long task_rlimit(const struct task_struct *tsk,
+               unsigned int limit)
+{
+       return ACCESS_ONCE(tsk->signal->rlim[limit].rlim_cur);
+}
+
+static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
+               unsigned int limit)
+{
+       return ACCESS_ONCE(tsk->signal->rlim[limit].rlim_max);
+}
+
+static inline unsigned long rlimit(unsigned int limit)
+{
+       return task_rlimit(current, limit);
+}
+
+static inline unsigned long rlimit_max(unsigned int limit)
+{
+       return task_rlimit_max(current, limit);
+}
+
 #endif /* __KERNEL__ */
 
 #endif