[PATCH net] page_pool: fix inconsistency for page_pool_ring_[un]lock()

Yunsheng Lin
2023-05-22T03:40:30Z

page_pool_ring_[un]lock() use in_softirq() to decide which
spin lock variant to use, and when they are called in the
context with in_softirq() being false, spin_lock_bh() is
called in page_pool_ring_lock() while spin_unlock() is
called in page_pool_ring_unlock(), because spin_lock_bh()
has disabled the softirq in page_pool_ring_lock(), which
causes inconsistency for spin lock pair calling.

This patch fixes it by returning in_softirq state from
page_pool_producer_lock(), and use it to decide which
spin lock variant to use in page_pool_producer_unlock().

As pool->ring has both producer and consumer lock, so
rename it to page_pool_producer_[un]lock() to reflect
the actual usage. Also move them to page_pool.c as they
are only used there, and remove the 'inline' as the
compiler may have better idea to do inlining or not.

Fixes: 7886244736a4 ("net: page_pool: Add bulk support for ptr_ring")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
include/net/page_pool.h | 18 ------------------
net/core/page_pool.c | 28 ++++++++++++++++++++++++++--
2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index c8ec2f34722b..126f9e294389 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -399,22 +399,4 @@ static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
page_pool_update_nid(pool, new_nid);
}

-static inline void page_pool_ring_lock(struct page_pool *pool)
- __acquires(&pool->ring.producer_lock)
-{
- if (in_softirq())
- spin_lock(&pool->ring.producer_lock);
- else
- spin_lock_bh(&pool->ring.producer_lock);
-}
-
-static inline void page_pool_ring_unlock(struct page_pool *pool)
- __releases(&pool->ring.producer_lock)
-{
- if (in_softirq())
- spin_unlock(&pool->ring.producer_lock);
- else
- spin_unlock_bh(&pool->ring.producer_lock);
-}
-
#endif /* _NET_PAGE_POOL_H */
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index e212e9d7edcb..a3e12a61d456 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -134,6 +134,29 @@ EXPORT_SYMBOL(page_pool_ethtool_stats_get);
#define recycle_stat_add(pool, __stat, val)
#endif

+static bool page_pool_producer_lock(struct page_pool *pool)
+ __acquires(&pool->ring.producer_lock)
+{
+ bool in_softirq = in_softirq();
+
+ if (in_softirq)
+ spin_lock(&pool->ring.producer_lock);
+ else
+ spin_lock_bh(&pool->ring.producer_lock);
+
+ return in_softirq;
+}
+
+static void page_pool_producer_unlock(struct page_pool *pool,
+ bool in_softirq)
+ __releases(&pool->ring.producer_lock)
+{
+ if (in_softirq)
+ spin_unlock(&pool->ring.producer_lock);
+ else
+ spin_unlock_bh(&pool->ring.producer_lock);
+}
+
static int page_pool_init(struct page_pool *pool,
const struct page_pool_params *params)
{
@@ -617,6 +640,7 @@ void page_pool_put_page_bulk(struct page_pool *pool, void **data,
int count)
{
int i, bulk_len = 0;
+ bool in_softirq;

for (i = 0; i < count; i++) {
struct page *page = virt_to_head_page(data[i]);
@@ -635,7 +659,7 @@ void page_pool_put_page_bulk(struct page_pool *pool, void **data,
return;

/* Bulk producer into ptr_ring page_pool cache */
- page_pool_ring_lock(pool);
+ in_softirq = page_pool_producer_lock(pool);
for (i = 0; i < bulk_len; i++) {
if (__ptr_ring_produce(&pool->ring, data[i])) {
/* ring full */
@@ -644,7 +668,7 @@ void page_pool_put_page_bulk(struct page_pool *pool, void **data,
}
}
recycle_stat_add(pool, ring, i);
- page_pool_ring_unlock(pool);
+ page_pool_producer_unlock(pool, in_softirq);

/* Hopefully all pages was return into ptr_ring */
if (likely(i == bulk_len))
--
2.33.0