From patchwork Thu Feb 6 22:56:37 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Kicinski X-Patchwork-Id: 13964037 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F27442417C2 for ; Thu, 6 Feb 2025 22:56:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738882614; cv=none; b=TFblzc5LHssNuCjgOcPCPBsqFFuqXj1NObZL8fsQBtpl8+hLqh+0+WpWK0FkNXxDsZezp6MVp0/psBoc0GPjRW4aaB/1DAh3D/U0Cf4AdGM1t9e+Vn8TgifVXqs0jLLs7m0r4KhHkv0aMSfNYnSH7G6BSn1sGQmSfPficq0nAEs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738882614; c=relaxed/simple; bh=aQVqifDDLfTy/kPKJCug5LsaEptcu23/8jOmA6Y0OEM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Z3YKi6yM9MMErMv+hDNXPN5v+fFA6Zhl/UWLQC0GVF6bHSFsQ5GNrEIoKNfCfb9p3+fI4hpUGWIl1eqkPvZdZpL4KVLZ+8iw4RKBlAGNRl4jpDbdT6a6EZkSTRRi2aU+3toew1KUQK0ukZOKC/wvOzaoS6u/V3cNI0995PtA3Yk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pult3Q98; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Pult3Q98" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A3AAC4CEE5; Thu, 6 Feb 2025 22:56:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738882613; bh=aQVqifDDLfTy/kPKJCug5LsaEptcu23/8jOmA6Y0OEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pult3Q98ham6osDvltJXTyTugY4tf6B/BmhxvtzGSqndex0FQzbHrwTiqgjIOQESP 1bgSaFBIcRCGP/zM/tmV70Jqr51JQ0/tYiHCh8E+txtA+Yr5+pxSNvNE+ONvvSMJI3 6mxU1PCmm9Yai5HPvwY4SJoDDtE1PJuj7g6jfBhv19sx9Ijej5KxPlShZn/dPnhLve 5nRn/D3/OJMlkMUdSooDf32wLGgWKscdD1vAGmn6mhL3Pqx+S8d1jxSYZkedi+3igO sAN/mCGCtCfe16TKHCBnZ6Ep/rJP8u8Wv3VK+gzj3wazt9Tr8uj+9qyJyK0v+XkB7h DjuYMe8T/HgVg== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, almasrymina@google.com, Jakub Kicinski , hawk@kernel.org, ilias.apalodimas@linaro.org, jdamato@fastly.com Subject: [PATCH net-next v2 3/4] net: page_pool: avoid false positive warning if NAPI was never added Date: Thu, 6 Feb 2025 14:56:37 -0800 Message-ID: <20250206225638.1387810-4-kuba@kernel.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250206225638.1387810-1-kuba@kernel.org> References: <20250206225638.1387810-1-kuba@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org 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 Reviewed-by: Mina Almasry --- 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(-) diff --git a/net/core/dev.h b/net/core/dev.h index a5b166bbd169..caa13e431a6b 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -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 diff --git a/net/core/page_pool.c b/net/core/page_pool.c index f5e908c9e7ad..b940c40ea2f2 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -25,6 +25,7 @@ #include +#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);