From nobody Mon Sep 29 21:26:49 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E870C2BB47 for ; Mon, 15 Aug 2022 23:47:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355120AbiHOXrH (ORCPT ); Mon, 15 Aug 2022 19:47:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354341AbiHOXlz (ORCPT ); Mon, 15 Aug 2022 19:41:55 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 134032CC81; Mon, 15 Aug 2022 13:13:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C9997B80EA8; Mon, 15 Aug 2022 20:12:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EA18C433D6; Mon, 15 Aug 2022 20:12:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660594378; bh=YcUUB4RedbZ+lubJgf+hTcDCMOcGMS1Aj3kO+WeMkUI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qC8NMKNDCdfDzOX7eT97IqQs7gckwxOHXo/H+m1puFaRKUOyuiEIKX5Z4OBdY/tVj KDMQ3spl2+f8qhdQ1i9520rRUPfdL9gT8SdSG4RGq3sgb2FrCsO00qUa1rBzBn1Oom BSf0ryBpJAIwdxzaHTXcolSw6Znf2wRk/sk6oJF0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maciej Fijalkowski , Daniel Borkmann , Magnus Karlsson , Sasha Levin Subject: [PATCH 5.19 0427/1157] selftests/xsk: Destroy BPF resources only when ctx refcount drops to 0 Date: Mon, 15 Aug 2022 19:56:23 +0200 Message-Id: <20220815180456.742270917@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180439.416659447@linuxfoundation.org> References: <20220815180439.416659447@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Maciej Fijalkowski [ Upstream commit 39e940d4abfabb08b6937a315546b24d10be67e3 ] Currently, xsk_socket__delete frees BPF resources regardless of ctx refcount. Xdpxceiver has a test to verify whether underlying BPF resources would not be wiped out after closing XSK socket that was bound to interface with other active sockets. From library's xsk part perspective it also means that the internal xsk context is shared and its refcount is bumped accordingly. After a switch to loading XDP prog based on previously opened XSK socket, mentioned xdpxceiver test fails with: not ok 16 [xdpxceiver.c:swap_xsk_resources:1334]: ERROR: 9/"Bad file desc= riptor which means that in swap_xsk_resources(), xsk_socket__delete() released xskmap which in turn caused a failure of xsk_socket__update_xskmap(). To fix this, when deleting socket, decrement ctx refcount before releasing BPF resources and do so only when refcount dropped to 0 which means there are no more active sockets for this ctx so BPF resources can be freed safely. Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devic= es") Signed-off-by: Maciej Fijalkowski Signed-off-by: Daniel Borkmann Acked-by: Magnus Karlsson Link: https://lore.kernel.org/bpf/20220629143458.934337-5-maciej.fijalkowsk= i@intel.com Signed-off-by: Sasha Levin --- tools/lib/bpf/xsk.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c index af136f73b09d..67dc010e9fe3 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -1147,8 +1147,6 @@ int xsk_socket__create_shared(struct xsk_socket **xsk= _ptr, goto out_mmap_tx; } =20 - ctx->prog_fd =3D -1; - if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) { err =3D __xsk_setup_xdp_prog(xsk, NULL); if (err) @@ -1229,7 +1227,10 @@ void xsk_socket__delete(struct xsk_socket *xsk) =20 ctx =3D xsk->ctx; umem =3D ctx->umem; - if (ctx->prog_fd !=3D -1) { + + xsk_put_ctx(ctx, true); + + if (!ctx->refcount) { xsk_delete_bpf_maps(xsk); close(ctx->prog_fd); if (ctx->has_bpf_link) @@ -1248,8 +1249,6 @@ void xsk_socket__delete(struct xsk_socket *xsk) } } =20 - xsk_put_ctx(ctx, true); - umem->refcount--; /* Do not close an fd that also has an associated umem connected * to it. --=20 2.35.1