On Tue, Jun 25, 2019 at 09:36:15PM -0400, Willem de Bruijn wrote:
On Tue, Jun 25, 2019 at 2:00 PM Ivan Khoronzhuk
<ivan.khoronzhuk@xxxxxxxxxx> wrote:
Add user counter allowing to delete pool only when no users.
It doesn't prevent pool from flush, only prevents freeing the
pool instance. Helps when no need to delete the pool and now
it's user responsibility to free it by calling page_pool_free()
while destroying procedure. It also makes to use page_pool_free()
explicitly, not fully hidden in xdp unreg, which looks more
correct after page pool "create" routine.
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
---
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index f07c518ef8a5..1ec838e9927e 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -101,6 +101,7 @@ struct page_pool {
struct ptr_ring ring;
atomic_t pages_state_release_cnt;
+ atomic_t user_cnt;
refcount_t?
yes, thanks.
};
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
@@ -183,6 +184,12 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
return page->dma_addr;
}
+/* used to prevent pool from deallocation */
+static inline void page_pool_get(struct page_pool *pool)
+{
+ atomic_inc(&pool->user_cnt);
+}
+
static inline bool is_page_pool_compiled_in(void)
{
#ifdef CONFIG_PAGE_POOL
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index b366f59885c1..169b0e3c870e 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -48,6 +48,7 @@ static int page_pool_init(struct page_pool *pool,
return -ENOMEM;
atomic_set(&pool->pages_state_release_cnt, 0);
+ atomic_set(&pool->user_cnt, 0);
if (pool->p.flags & PP_FLAG_DMA_MAP)
get_device(pool->p.dev);
@@ -70,6 +71,8 @@ struct page_pool *page_pool_create(const struct page_pool_params *params)
kfree(pool);
return ERR_PTR(err);
}
+
+ page_pool_get(pool);
return pool;
}
EXPORT_SYMBOL(page_pool_create);
@@ -356,6 +359,10 @@ static void __warn_in_flight(struct page_pool *pool)
void __page_pool_free(struct page_pool *pool)
{
+ /* free only if no users */
+ if (!atomic_dec_and_test(&pool->user_cnt))
+ return;
+
WARN(pool->alloc.count, "API usage violation");
WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty");
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 829377cc83db..04bdcd784d2e 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -372,6 +372,9 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
mutex_unlock(&mem_id_lock);
+ if (type == MEM_TYPE_PAGE_POOL)
+ page_pool_get(xdp_alloc->page_pool);
+
need an analogous page_pool_put in xdp_rxq_info_unreg_mem_model? mlx5
does not use that inverse function, but intel drivers do.
no need, it's put after call to page_pool_free() in unreg workqueue.
trace_mem_connect(xdp_alloc, xdp_rxq);
return 0;
err:
--
2.17.1
--
Regards,
Ivan Khoronzhuk
