Commit 7c9e6942 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by David S. Miller
Browse files

page_pool: add destroy attempts counter and rename tracepoint 



When Jonathan change the page_pool to become responsible to its
own shutdown via deferred work queue, then the disconnect_cnt
counter was removed from xdp memory model tracepoint.

This patch change the page_pool_inflight tracepoint name to
page_pool_release, because it reflects the new responsability
better.  And it reintroduces a counter that reflect the number of
times page_pool_release have been tried.

The counter is also used by the code, to only empty the alloc
cache once.  With a stuck work queue running every second and
counter being 64-bit, it will overrun in approx 584 billion
years. For comparison, Earth lifetime expectancy is 7.5 billion
years, before the Sun will engulf, and destroy, the Earth.

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c491eae8

include/net/page_pool.h

+2 −0
Original line number Diff line number Diff line
@@ -112,6 +112,8 @@ struct page_pool { 
	 * refcnt serves purpose is to simplify drivers error handling.

	 */

	refcount_t user_cnt;



	u64 destroy_cnt;

};



struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);

include/trace/events/page_pool.h

+6 −3
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ 


#include <net/page_pool.h>



TRACE_EVENT(page_pool_inflight,

TRACE_EVENT(page_pool_release,



	TP_PROTO(const struct page_pool *pool,

		 s32 inflight, u32 hold, u32 release),
@@ -22,6 +22,7 @@ TRACE_EVENT(page_pool_inflight, 
		__field(s32,	inflight)

		__field(u32,	hold)

		__field(u32,	release)

		__field(u64,	cnt)

	),



	TP_fast_assign(
@@ -29,10 +30,12 @@ TRACE_EVENT(page_pool_inflight, 
		__entry->inflight	= inflight;

		__entry->hold		= hold;

		__entry->release	= release;

		__entry->cnt		= pool->destroy_cnt;

	),



	TP_printk("page_pool=%p inflight=%d hold=%u release=%u",

	  __entry->pool, __entry->inflight, __entry->hold, __entry->release)

	TP_printk("page_pool=%p inflight=%d hold=%u release=%u cnt=%llu",

		__entry->pool, __entry->inflight, __entry->hold,

		__entry->release, __entry->cnt)

);



TRACE_EVENT(page_pool_state_release,

net/core/page_pool.c

+11 −2
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ static s32 page_pool_inflight(struct page_pool *pool) 


	inflight = _distance(hold_cnt, release_cnt);



	trace_page_pool_inflight(pool, inflight, hold_cnt, release_cnt);

	trace_page_pool_release(pool, inflight, hold_cnt, release_cnt);

	WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight);



	return inflight;
@@ -349,10 +349,13 @@ static void page_pool_free(struct page_pool *pool) 
	kfree(pool);

}



static void page_pool_scrub(struct page_pool *pool)

static void page_pool_empty_alloc_cache_once(struct page_pool *pool)

{

	struct page *page;



	if (pool->destroy_cnt)

		return;



	/* Empty alloc cache, assume caller made sure this is

	 * no-longer in use, and page_pool_alloc_pages() cannot be

	 * call concurrently.
@@ -361,6 +364,12 @@ static void page_pool_scrub(struct page_pool *pool) 
		page = pool->alloc.cache[--pool->alloc.count];

		__page_pool_return_page(pool, page);

	}

}



static void page_pool_scrub(struct page_pool *pool)

{

	page_pool_empty_alloc_cache_once(pool);

	pool->destroy_cnt++;



	/* No more consumers should exist, but producers could still

	 * be in-flight.

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