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-rw-r--r--include/linux/cpuset.h43
1 files changed, 43 insertions, 0 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index a73454aec333..20b51cab6593 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -86,9 +86,44 @@ extern void rebuild_sched_domains(void);
extern void cpuset_print_task_mems_allowed(struct task_struct *p);
+/*
+ * reading current mems_allowed and mempolicy in the fastpath must protected
+ * by get_mems_allowed()
+ */
+static inline void get_mems_allowed(void)
+{
+ current->mems_allowed_change_disable++;
+
+ /*
+ * ensure that reading mems_allowed and mempolicy happens after the
+ * update of ->mems_allowed_change_disable.
+ *
+ * the write-side task finds ->mems_allowed_change_disable is not 0,
+ * and knows the read-side task is reading mems_allowed or mempolicy,
+ * so it will clear old bits lazily.
+ */
+ smp_mb();
+}
+
+static inline void put_mems_allowed(void)
+{
+ /*
+ * ensure that reading mems_allowed and mempolicy before reducing
+ * mems_allowed_change_disable.
+ *
+ * the write-side task will know that the read-side task is still
+ * reading mems_allowed or mempolicy, don't clears old bits in the
+ * nodemask.
+ */
+ smp_mb();
+ --ACCESS_ONCE(current->mems_allowed_change_disable);
+}
+
static inline void set_mems_allowed(nodemask_t nodemask)
{
+ task_lock(current);
current->mems_allowed = nodemask;
+ task_unlock(current);
}
#else /* !CONFIG_CPUSETS */
@@ -187,6 +222,14 @@ static inline void set_mems_allowed(nodemask_t nodemask)
{
}
+static inline void get_mems_allowed(void)
+{
+}
+
+static inline void put_mems_allowed(void)
+{
+}
+
#endif /* !CONFIG_CPUSETS */
#endif /* _LINUX_CPUSET_H */