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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: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Dangaard Brouer 2019-11-16 12:22:43 +01:00 committed by David S. Miller
parent c491eae8f9
commit 7c9e69428d
3 changed files with 19 additions and 5 deletions
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2
include/net/page_pool.h
View File

@ -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);

9
include/trace/events/page_pool.h
View File

@ -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,

13
net/core/page_pool.c
View File

@ -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.