On 2016年06月01日 20:54, Michael S. Tsirkin wrote:
A simple array based FIFO of pointers. Intended for net stack so uses
skbs for type safety. Implemented as a set of wrappers around ptr_array.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
include/linux/skb_array.h | 129 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 129 insertions(+)
create mode 100644 include/linux/skb_array.h
diff --git a/include/linux/skb_array.h b/include/linux/skb_array.h
new file mode 100644
index 0000000..cb67076
--- /dev/null
+++ b/include/linux/skb_array.h
@@ -0,0 +1,129 @@
+/*
+ * Definitions for the 'struct skb_array' datastructure.
+ *
+ * Author:
+ * Michael S. Tsirkin <mst@xxxxxxxxxx>
+ *
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * Limited-size FIFO of skbs. Can be used more or less whenever
+ * sk_buff_head can be used, except you need to know the queue size in
+ * advance.
+ * Implemented as a type-safe wrapper around ptr_ring.
+ */
+
+#ifndef _LINUX_SKB_ARRAY_H
+#define _LINUX_SKB_ARRAY_H 1
+
+#ifdef __KERNEL__
+#include <linux/ptr_ring.h>
+#include <linux/skbuff.h>
+#endif
+
+struct skb_array {
+ struct ptr_ring ring;
+};
+
+/* Might be slightly faster than skb_array_full below, but callers invoking
+ * this in a loop must use a compiler barrier, for example cpu_relax().
+ */
+static inline bool __skb_array_full(struct skb_array *a)
+{
+ return __ptr_ring_full(&a->ring);
+}
+
+static inline bool skb_array_full(struct skb_array *a)
+{
+ return ptr_ring_full(&a->ring);
+}
+
+static inline int skb_array_produce(struct skb_array *a, struct sk_buff *skb)
+{
+ return ptr_ring_produce(&a->ring, skb);
+}
+
+static inline int skb_array_produce_irq(struct skb_array *a, struct sk_buff *skb)
+{
+ return ptr_ring_produce_irq(&a->ring, skb);
+}
+
+static inline int skb_array_produce_bh(struct skb_array *a, struct sk_buff *skb)
+{
+ return ptr_ring_produce_bh(&a->ring, skb);
+}
+
+static inline int skb_array_produce_any(struct skb_array *a, struct sk_buff *skb)
+{
+ return ptr_ring_produce_any(&a->ring, skb);
+}
+
+/* Might be slightly faster than skb_array_empty below, but callers invoking
+ * this in a loop must take care to use a compiler barrier, for example
+ * cpu_relax().
+ */
+static inline bool __skb_array_empty(struct skb_array *a)
+{
+ return !__ptr_ring_peek(&a->ring);
+}
+
+static inline bool skb_array_empty(struct skb_array *a)
+{
+ return ptr_ring_empty(&a->ring);
+}
+
+static inline struct sk_buff *skb_array_consume(struct skb_array *a)
+{
+ return ptr_ring_consume(&a->ring);
+}
+
+static inline struct sk_buff *skb_array_consume_irq(struct skb_array *a)
+{
+ return ptr_ring_consume_irq(&a->ring);
+}
+
+static inline struct sk_buff *skb_array_consume_any(struct skb_array *a)
+{
+ return ptr_ring_consume_any(&a->ring);
+}
+
+static inline struct sk_buff *skb_array_consume_bh(struct skb_array *a)
+{
+ return ptr_ring_consume_bh(&a->ring);
+}
+
+static inline int skb_array_peek_len(struct skb_array *a)
+{
+ return PTR_RING_PEEK_FIELD(&a->ring, struct sk_buff, len, 0);
+}
An interesting case for tun is peek the length of a tagged packet. In
this case, len should be increased accordingly. So this simple filed
peeking won't work.
Do we need a callback here?
+
+static inline int skb_array_peek_len_irq(struct skb_array *a)
+{
+ return PTR_RING_PEEK_FIELD_IRQ(&a->ring, struct sk_buff, len, 0);
+}
+
+static inline int skb_array_peek_len_bh(struct skb_array *a)
+{
+ return PTR_RING_PEEK_FIELD_BH(&a->ring, struct sk_buff, len, 0);
+}
+
+static inline int skb_array_peek_len_any(struct skb_array *a)
+{
+ return PTR_RING_PEEK_FIELD_ANY(&a->ring, struct sk_buff, len, 0);
+}
+
+static inline int skb_array_init(struct skb_array *a, int size, gfp_t gfp)
+{
+ return ptr_ring_init(&a->ring, size, gfp);
+}
+
+static inline void skb_array_cleanup(struct skb_array *a)
+{
+ ptr_ring_cleanup(&a->ring);
+}
+
+#endif /* _LINUX_SKB_ARRAY_H */
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