Merge tag 'sched-rt-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git...

[thirdparty/kernel/linux.git] / include / linux / srcu.h

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 236610e4a8fa5d704b7e4bb243b720a7c5fc1283..835bbb2d1f88ad7efb4d5db4f4bf8e71fc8e22e9 100644 (file)
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -57,10 +57,45 @@ void cleanup_srcu_struct(struct srcu_struct *ssp);
 int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
 void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp);
 void synchronize_srcu(struct srcu_struct *ssp);
+
+#define SRCU_GET_STATE_COMPLETED 0x1
+
+/**
+ * get_completed_synchronize_srcu - Return a pre-completed polled state cookie
+ *
+ * Returns a value that poll_state_synchronize_srcu() will always treat
+ * as a cookie whose grace period has already completed.
+ */
+static inline unsigned long get_completed_synchronize_srcu(void)
+{
+       return SRCU_GET_STATE_COMPLETED;
+}
+
 unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp);
 unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp);
 bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie);
 
+// Maximum number of unsigned long values corresponding to
+// not-yet-completed SRCU grace periods.
+#define NUM_ACTIVE_SRCU_POLL_OLDSTATE 2
+
+/**
+ * same_state_synchronize_srcu - Are two old-state values identical?
+ * @oldstate1: First old-state value.
+ * @oldstate2: Second old-state value.
+ *
+ * The two old-state values must have been obtained from either
+ * get_state_synchronize_srcu(), start_poll_synchronize_srcu(), or
+ * get_completed_synchronize_srcu().  Returns @true if the two values are
+ * identical and @false otherwise.  This allows structures whose lifetimes
+ * are tracked by old-state values to push these values to a list header,
+ * allowing those structures to be slightly smaller.
+ */
+static inline bool same_state_synchronize_srcu(unsigned long oldstate1, unsigned long oldstate2)
+{
+       return oldstate1 == oldstate2;
+}
+
 #ifdef CONFIG_NEED_SRCU_NMI_SAFE
 int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp);
 void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) __releases(ssp);
@@ -343,6 +378,20 @@ static inline void smp_mb__after_srcu_read_unlock(void)
        /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
 }
 
+/**
+ * smp_mb__after_srcu_read_lock - ensure full ordering after srcu_read_lock
+ *
+ * Converts the preceding srcu_read_lock into a two-way memory barrier.
+ *
+ * Call this after srcu_read_lock, to guarantee that all memory operations
+ * that occur after smp_mb__after_srcu_read_lock will appear to happen after
+ * the preceding srcu_read_lock.
+ */
+static inline void smp_mb__after_srcu_read_lock(void)
+{
+       /* __srcu_read_lock has smp_mb() internally so nothing to do here. */
+}
+
 DEFINE_LOCK_GUARD_1(srcu, struct srcu_struct,
                    _T->idx = srcu_read_lock(_T->lock),
                    srcu_read_unlock(_T->lock, _T->idx),