xdp: add tracepoints for XDP mem

These tracepoints make it easier to troubleshoot XDP mem id disconnect.

The xdp:mem_disconnect tracepoint cannot be replaced via kprobe. It is
placed at the last stable place for the pointer to struct xdp_mem_allocator,
just before it's scheduled for RCU removal. It also extract info on
'safe_to_remove' and 'force'.

Detailed info about in-flight pages is not available at this layer. The next
patch will added tracepoints needed at the page_pool layer for this.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 138 insertions, 0 deletions

diff --git a/include/net/xdp_priv.h b/include/net/xdp_priv.h
new file mode 100644
index 000000000000..6a8cba6ea79a
--- /dev/null
+++ b/include/net/xdp_priv.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_NET_XDP_PRIV_H__
+#define __LINUX_NET_XDP_PRIV_H__
+
+#include <linux/rhashtable.h>
+
+/* Private to net/core/xdp.c, but used by trace/events/xdp.h */
+struct xdp_mem_allocator {
+	struct xdp_mem_info mem;
+	union {
+		void *allocator;
+		struct page_pool *page_pool;
+		struct zero_copy_allocator *zc_alloc;
+	};
+	int disconnect_cnt;
+	unsigned long defer_start;
+	struct rhash_head node;
+	struct rcu_head rcu;
+	struct delayed_work defer_wq;
+	unsigned long defer_warn;
+};
+
+#endif /* __LINUX_NET_XDP_PRIV_H__ */
diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index e95cb86b65cf..bb5e380e2ef3 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -269,6 +269,121 @@ TRACE_EVENT(xdp_devmap_xmit,
 		  __entry->from_ifindex, __entry->to_ifindex, __entry->err)
 );
 
+/* Expect users already include <net/xdp.h>, but not xdp_priv.h */
+#include <net/xdp_priv.h>
+
+#define __MEM_TYPE_MAP(FN)	\
+	FN(PAGE_SHARED)		\
+	FN(PAGE_ORDER0)		\
+	FN(PAGE_POOL)		\
+	FN(ZERO_COPY)
+
+#define __MEM_TYPE_TP_FN(x)	\
+	TRACE_DEFINE_ENUM(MEM_TYPE_##x);
+#define __MEM_TYPE_SYM_FN(x)	\
+	{ MEM_TYPE_##x, #x },
+#define __MEM_TYPE_SYM_TAB	\
+	__MEM_TYPE_MAP(__MEM_TYPE_SYM_FN) { -1, 0 }
+__MEM_TYPE_MAP(__MEM_TYPE_TP_FN)
+
+TRACE_EVENT(mem_disconnect,
+
+	TP_PROTO(const struct xdp_mem_allocator *xa,
+		 bool safe_to_remove, bool force),
+
+	TP_ARGS(xa, safe_to_remove, force),
+
+	TP_STRUCT__entry(
+		__field(const struct xdp_mem_allocator *,	xa)
+		__field(u32,		mem_id)
+		__field(u32,		mem_type)
+		__field(const void *,	allocator)
+		__field(bool,		safe_to_remove)
+		__field(bool,		force)
+		__field(int,		disconnect_cnt)
+	),
+
+	TP_fast_assign(
+		__entry->xa		= xa;
+		__entry->mem_id		= xa->mem.id;
+		__entry->mem_type	= xa->mem.type;
+		__entry->allocator	= xa->allocator;
+		__entry->safe_to_remove	= safe_to_remove;
+		__entry->force		= force;
+		__entry->disconnect_cnt	= xa->disconnect_cnt;
+	),
+
+	TP_printk("mem_id=%d mem_type=%s allocator=%p"
+		  " safe_to_remove=%s force=%s disconnect_cnt=%d",
+		  __entry->mem_id,
+		  __print_symbolic(__entry->mem_type, __MEM_TYPE_SYM_TAB),
+		  __entry->allocator,
+		  __entry->safe_to_remove ? "true" : "false",
+		  __entry->force ? "true" : "false",
+		  __entry->disconnect_cnt
+	)
+);
+
+TRACE_EVENT(mem_connect,
+
+	TP_PROTO(const struct xdp_mem_allocator *xa,
+		 const struct xdp_rxq_info *rxq),
+
+	TP_ARGS(xa, rxq),
+
+	TP_STRUCT__entry(
+		__field(const struct xdp_mem_allocator *,	xa)
+		__field(u32,		mem_id)
+		__field(u32,		mem_type)
+		__field(const void *,	allocator)
+		__field(const struct xdp_rxq_info *,		rxq)
+		__field(int,		ifindex)
+	),
+
+	TP_fast_assign(
+		__entry->xa		= xa;
+		__entry->mem_id		= xa->mem.id;
+		__entry->mem_type	= xa->mem.type;
+		__entry->allocator	= xa->allocator;
+		__entry->rxq		= rxq;
+		__entry->ifindex	= rxq->dev->ifindex;
+	),
+
+	TP_printk("mem_id=%d mem_type=%s allocator=%p"
+		  " ifindex=%d",
+		  __entry->mem_id,
+		  __print_symbolic(__entry->mem_type, __MEM_TYPE_SYM_TAB),
+		  __entry->allocator,
+		  __entry->ifindex
+	)
+);
+
+TRACE_EVENT(mem_return_failed,
+
+	TP_PROTO(const struct xdp_mem_info *mem,
+		 const struct page *page),
+
+	TP_ARGS(mem, page),
+
+	TP_STRUCT__entry(
+		__field(const struct page *,	page)
+		__field(u32,		mem_id)
+		__field(u32,		mem_type)
+	),
+
+	TP_fast_assign(
+		__entry->page		= page;
+		__entry->mem_id		= mem->id;
+		__entry->mem_type	= mem->type;
+	),
+
+	TP_printk("mem_id=%d mem_type=%s page=%p",
+		  __entry->mem_id,
+		  __print_symbolic(__entry->mem_type, __MEM_TYPE_SYM_TAB),
+		  __entry->page
+	)
+);
+
 #endif /* _TRACE_XDP_H */
 
 #include <trace/define_trace.h>