page_pool: add tracepoints for page_pool with details need by XDP

The xdp tracepoints for mem id disconnect don't carry information about, why
it was not safe_to_remove.  The tracepoint page_pool:page_pool_inflight in
this patch can be used for extract this info for further debugging.

This patchset also adds tracepoint for the pages_state_* release/hold
transitions, including a pointer to the page.  This can be used for stats
about in-flight pages, or used to debug page leakage via keeping track of
page pointer and combining this with kprobe for __put_page().

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

diff --git a/include/trace/events/page_pool.h b/include/trace/events/page_pool.h
new file mode 100644 (file)
index 0000000..47b5ee8
--- /dev/null
+++ b/include/trace/events/page_pool.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM page_pool
+
+#if !defined(_TRACE_PAGE_POOL_H) || defined(TRACE_HEADER_MULTI_READ)
+#define      _TRACE_PAGE_POOL_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+#include <net/page_pool.h>
+
+TRACE_EVENT(page_pool_inflight,
+
+       TP_PROTO(const struct page_pool *pool,
+                s32 inflight, u32 hold, u32 release),
+
+       TP_ARGS(pool, inflight, hold, release),
+
+       TP_STRUCT__entry(
+               __field(const struct page_pool *, pool)
+               __field(s32,    inflight)
+               __field(u32,    hold)
+               __field(u32,    release)
+       ),
+
+       TP_fast_assign(
+               __entry->pool           = pool;
+               __entry->inflight       = inflight;
+               __entry->hold           = hold;
+               __entry->release        = release;
+       ),
+
+       TP_printk("page_pool=%p inflight=%d hold=%u release=%u",
+         __entry->pool, __entry->inflight, __entry->hold, __entry->release)
+);
+
+TRACE_EVENT(page_pool_state_release,
+
+       TP_PROTO(const struct page_pool *pool,
+                const struct page *page, u32 release),
+
+       TP_ARGS(pool, page, release),
+
+       TP_STRUCT__entry(
+               __field(const struct page_pool *,       pool)
+               __field(const struct page *,            page)
+               __field(u32,                            release)
+       ),
+
+       TP_fast_assign(
+               __entry->pool           = pool;
+               __entry->page           = page;
+               __entry->release        = release;
+       ),
+
+       TP_printk("page_pool=%p page=%p release=%u",
+                 __entry->pool, __entry->page, __entry->release)
+);
+
+TRACE_EVENT(page_pool_state_hold,
+
+       TP_PROTO(const struct page_pool *pool,
+                const struct page *page, u32 hold),
+
+       TP_ARGS(pool, page, hold),
+
+       TP_STRUCT__entry(
+               __field(const struct page_pool *,       pool)
+               __field(const struct page *,            page)
+               __field(u32,                            hold)
+       ),
+
+       TP_fast_assign(
+               __entry->pool   = pool;
+               __entry->page   = page;
+               __entry->hold   = hold;
+       ),
+
+       TP_printk("page_pool=%p page=%p hold=%u",
+                 __entry->pool, __entry->page, __entry->hold)
+);
+
+#endif /* _TRACE_PAGE_POOL_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

diff --git a/net/core/net-traces.c b/net/core/net-traces.c
index 470b179..283ddb2 100644 (file)
--- a/net/core/net-traces.c
+++ b/net/core/net-traces.c
@@ -43,6 +43,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(fdb_delete);
 EXPORT_TRACEPOINT_SYMBOL_GPL(br_fdb_update);
 #endif
 
+#if IS_ENABLED(CONFIG_PAGE_POOL)
+#include <trace/events/page_pool.h>
+#endif
+
 #include <trace/events/neigh.h>
 EXPORT_TRACEPOINT_SYMBOL_GPL(neigh_update);
 EXPORT_TRACEPOINT_SYMBOL_GPL(neigh_update_done);

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 42c3b0a..f55ab05 100644 (file)
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -4,6 +4,7 @@
  *     Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
  *     Copyright (C) 2016 Red Hat, Inc.
  */
+
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
@@ -14,6 +15,8 @@
 #include <linux/page-flags.h>
 #include <linux/mm.h> /* for __put_page() */
 
+#include <trace/events/page_pool.h>
+
 static int page_pool_init(struct page_pool *pool,
                          const struct page_pool_params *params)
 {
@@ -156,6 +159,8 @@ skip_dma_map:
        /* Track how many pages are held 'in-flight' */
        pool->pages_state_hold_cnt++;
 
+       trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
+
        /* When page just alloc'ed is should/must have refcnt 1. */
        return page;
 }
@@ -191,7 +196,7 @@ static s32 page_pool_inflight(struct page_pool *pool)
 
        distance = _distance(hold_cnt, release_cnt);
 
-       /* TODO: Add tracepoint here */
+       trace_page_pool_inflight(pool, distance, hold_cnt, release_cnt);
        return distance;
 }
 
@@ -222,6 +227,8 @@ static void __page_pool_clean_page(struct page_pool *pool,
        page->dma_addr = 0;
 skip_dma_unmap:
        atomic_inc(&pool->pages_state_release_cnt);
+       trace_page_pool_state_release(pool, page,
+                             atomic_read(&pool->pages_state_release_cnt));
 }
 
 /* unmap the page and clean our state */