V4L/DVB (13946): proc_fops: convert av7110

[safe/jmp/linux-2.6] / kernel / srcu.c

diff --git a/kernel/srcu.c b/kernel/srcu.c
index 7e1979f..818d7d9 100644 (file)
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -42,12 +42,14 @@
  * to any other function.  Each srcu_struct represents a separate domain
  * of SRCU protection.
  */
-void init_srcu_struct(struct srcu_struct *sp)
+int init_srcu_struct(struct srcu_struct *sp)
 {
        sp->completed = 0;
-       sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
        mutex_init(&sp->mutex);
+       sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
+       return (sp->per_cpu_ref ? 0 : -ENOMEM);
 }
+EXPORT_SYMBOL_GPL(init_srcu_struct);
 
 /*
  * srcu_readers_active_idx -- returns approximate number of readers
@@ -73,7 +75,7 @@ static int srcu_readers_active_idx(struct srcu_struct *sp, int idx)
  * severe errors when invoked on an active srcu_struct.  That said, it
  * can be useful as an error check at cleanup time.
  */
-int srcu_readers_active(struct srcu_struct *sp)
+static int srcu_readers_active(struct srcu_struct *sp)
 {
        return srcu_readers_active_idx(sp, 0) + srcu_readers_active_idx(sp, 1);
 }
@@ -96,6 +98,7 @@ void cleanup_srcu_struct(struct srcu_struct *sp)
        free_percpu(sp->per_cpu_ref);
        sp->per_cpu_ref = NULL;
 }
+EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
 
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
@@ -117,6 +120,7 @@ int srcu_read_lock(struct srcu_struct *sp)
        preempt_enable();
        return idx;
 }
+EXPORT_SYMBOL_GPL(srcu_read_lock);
 
 /**
  * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
@@ -135,22 +139,12 @@ void srcu_read_unlock(struct srcu_struct *sp, int idx)
        per_cpu_ptr(sp->per_cpu_ref, smp_processor_id())->c[idx]--;
        preempt_enable();
 }
+EXPORT_SYMBOL_GPL(srcu_read_unlock);
 
-/**
- * synchronize_srcu - wait for prior SRCU read-side critical-section completion
- * @sp: srcu_struct with which to synchronize.
- *
- * Flip the completed counter, and wait for the old count to drain to zero.
- * As with classic RCU, the updater must use some separate means of
- * synchronizing concurrent updates.  Can block; must be called from
- * process context.
- *
- * Note that it is illegal to call synchornize_srcu() from the corresponding
- * SRCU read-side critical section; doing so will result in deadlock.
- * However, it is perfectly legal to call synchronize_srcu() on one
- * srcu_struct from some other srcu_struct's read-side critical section.
+/*
+ * Helper function for synchronize_srcu() and synchronize_srcu_expedited().
  */
-void synchronize_srcu(struct srcu_struct *sp)
+void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
 {
        int idx;
 
@@ -172,7 +166,7 @@ void synchronize_srcu(struct srcu_struct *sp)
                return;
        }
 
-       synchronize_sched();  /* Force memory barrier on all CPUs. */
+       sync_func();  /* Force memory barrier on all CPUs. */
 
        /*
         * The preceding synchronize_sched() ensures that any CPU that
@@ -189,7 +183,7 @@ void synchronize_srcu(struct srcu_struct *sp)
        idx = sp->completed & 0x1;
        sp->completed++;
 
-       synchronize_sched();  /* Force memory barrier on all CPUs. */
+       sync_func();  /* Force memory barrier on all CPUs. */
 
        /*
         * At this point, because of the preceding synchronize_sched(),
@@ -202,7 +196,7 @@ void synchronize_srcu(struct srcu_struct *sp)
        while (srcu_readers_active_idx(sp, idx))
                schedule_timeout_interruptible(1);
 
-       synchronize_sched();  /* Force memory barrier on all CPUs. */
+       sync_func();  /* Force memory barrier on all CPUs. */
 
        /*
         * The preceding synchronize_sched() forces all srcu_read_unlock()
@@ -236,6 +230,47 @@ void synchronize_srcu(struct srcu_struct *sp)
 }
 
 /**
+ * synchronize_srcu - wait for prior SRCU read-side critical-section completion
+ * @sp: srcu_struct with which to synchronize.
+ *
+ * Flip the completed counter, and wait for the old count to drain to zero.
+ * As with classic RCU, the updater must use some separate means of
+ * synchronizing concurrent updates.  Can block; must be called from
+ * process context.
+ *
+ * Note that it is illegal to call synchronize_srcu() from the corresponding
+ * SRCU read-side critical section; doing so will result in deadlock.
+ * However, it is perfectly legal to call synchronize_srcu() on one
+ * srcu_struct from some other srcu_struct's read-side critical section.
+ */
+void synchronize_srcu(struct srcu_struct *sp)
+{
+       __synchronize_srcu(sp, synchronize_sched);
+}
+EXPORT_SYMBOL_GPL(synchronize_srcu);
+
+/**
+ * synchronize_srcu_expedited - like synchronize_srcu, but less patient
+ * @sp: srcu_struct with which to synchronize.
+ *
+ * Flip the completed counter, and wait for the old count to drain to zero.
+ * As with classic RCU, the updater must use some separate means of
+ * synchronizing concurrent updates.  Can block; must be called from
+ * process context.
+ *
+ * Note that it is illegal to call synchronize_srcu_expedited()
+ * from the corresponding SRCU read-side critical section; doing so
+ * will result in deadlock.  However, it is perfectly legal to call
+ * synchronize_srcu_expedited() on one srcu_struct from some other
+ * srcu_struct's read-side critical section.
+ */
+void synchronize_srcu_expedited(struct srcu_struct *sp)
+{
+       __synchronize_srcu(sp, synchronize_sched_expedited);
+}
+EXPORT_SYMBOL_GPL(synchronize_srcu_expedited);
+
+/**
  * srcu_batches_completed - return batches completed.
  * @sp: srcu_struct on which to report batch completion.
  *
@@ -247,11 +282,4 @@ long srcu_batches_completed(struct srcu_struct *sp)
 {
        return sp->completed;
 }
-
-EXPORT_SYMBOL_GPL(init_srcu_struct);
-EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
-EXPORT_SYMBOL_GPL(srcu_read_lock);
-EXPORT_SYMBOL_GPL(srcu_read_unlock);
-EXPORT_SYMBOL_GPL(synchronize_srcu);
 EXPORT_SYMBOL_GPL(srcu_batches_completed);
-EXPORT_SYMBOL_GPL(srcu_readers_active);