@@ -299,6 +299,18 @@ void xdp_do_check_flushed(struct napi_struct *napi);
static inline void xdp_do_check_flushed(struct napi_struct *napi) { }
#endif
+/* Best effort check that NAPI is not idle (can't be scheduled to run) */
+static inline void napi_assert_will_not_race(const struct napi_struct *napi)
+{
+ /* uninitialized instance, can't race */
+ if (!napi->poll_list.next)
+ return;
+
+ /* SCHED bit is set on disabled instances */
+ WARN_ON(!test_bit(NAPI_STATE_SCHED, &napi->state));
+ WARN_ON(READ_ONCE(napi->list_owner) != -1);
+}
+
void kick_defer_list_purge(struct softnet_data *sd, unsigned int cpu);
#define XMIT_RECURSION_LIMIT 8
@@ -25,6 +25,7 @@
#include <trace/events/page_pool.h>
+#include "dev.h"
#include "mp_dmabuf_devmem.h"
#include "netmem_priv.h"
#include "page_pool_priv.h"
@@ -1140,11 +1141,7 @@ void page_pool_disable_direct_recycling(struct page_pool *pool)
if (!pool->p.napi)
return;
- /* To avoid races with recycling and additional barriers make sure
- * pool and NAPI are unlinked when NAPI is disabled.
- */
- WARN_ON(!test_bit(NAPI_STATE_SCHED, &pool->p.napi->state));
- WARN_ON(READ_ONCE(pool->p.napi->list_owner) != -1);
+ napi_assert_will_not_race(pool->p.napi);
mutex_lock(&page_pools_lock);
WRITE_ONCE(pool->p.napi, NULL);
We expect NAPI to be in disabled state when page pool is torn down. But it is also legal if the NAPI is completely uninitialized. Signed-off-by: Jakub Kicinski <kuba@kernel.org> --- v2: new patch v1: https://lore.kernel.org/20250205190131.564456-1-kuba@kernel.org CC: hawk@kernel.org CC: ilias.apalodimas@linaro.org CC: jdamato@fastly.com --- net/core/dev.h | 12 ++++++++++++ net/core/page_pool.c | 7 ++----- 2 files changed, 14 insertions(+), 5 deletions(-)