From: Yunsheng Lin <linyunsheng@huawei.com>
Date: Mon, 22 May 2023 03:17:14 +0000 (+0800)
Subject: page_pool: fix inconsistency for page_pool_ring_[un]lock()
X-Git-Tag: v6.3.5~4
X-Git-Url: http://git.itanic.dy.fi/?p=linux-stable;a=commitdiff_plain;h=901f50d275cc574b2bf58c4cd0c8a8b3d1fabe6d

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

commit 368d3cb406cdd074d1df2ad9ec06d1bfcb664882 upstream.

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>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Link: https://lore.kernel.org/r/20230522031714.5089-1-linyunsheng@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index ddfa0b328677..41679d348e81 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -393,22 +393,4 @@ 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 193c18799865..2396c99bedea 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -133,6 +133,29 @@ 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)
 {
@@ -615,6 +638,7 @@ 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]);
@@ -633,7 +657,7 @@ 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 */
@@ -642,7 +666,7 @@ 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))