From mboxrd@z Thu Jan 1 00:00:00 1970 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 F2066C28B2B for ; Fri, 19 Aug 2022 16:09:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351649AbiHSQJI (ORCPT ); Fri, 19 Aug 2022 12:09:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351712AbiHSQGY (ORCPT ); Fri, 19 Aug 2022 12:06:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDFF1104752; Fri, 19 Aug 2022 08:55:49 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 40A0A616FD; Fri, 19 Aug 2022 15:55:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F8A2C433C1; Fri, 19 Aug 2022 15:55:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660924547; bh=BBlLD9KoaasuWYg45i60iMwuJJMjp+3syWpm+KckQvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MNexp6loyY1pvZIjAvVHKzwtHWzLLUYzcZth/a8RyTSPHdYSaXRmJOUVHZX6LNtsb t8tr4niZkRqh2FiTMB4SzShq2iN/I8tyDGVWXTcC1V84vI0JtHtXUEDflMAMLp3ZFv rs6vQaK5l/PyDHO1b5xn7Ep+qWFqQMFrk/i/bDI8= 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 5.10 206/545] selftests/xsk: Destroy BPF resources only when ctx refcount drops to 0 Date: Fri, 19 Aug 2022 17:39:36 +0200 Message-Id: <20220819153838.599918925@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819153829.135562864@linuxfoundation.org> References: <20220819153829.135562864@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 descriptor 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 devices") Signed-off-by: Maciej Fijalkowski Signed-off-by: Daniel Borkmann Acked-by: Magnus Karlsson Link: https://lore.kernel.org/bpf/20220629143458.934337-5-maciej.fijalkowski@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 c4390ef98b19..e8745f646371 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -849,8 +849,6 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr, goto out_mmap_tx; } - ctx->prog_fd = -1; - if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) { err = xsk_setup_xdp_prog(xsk); if (err) @@ -931,7 +929,10 @@ void xsk_socket__delete(struct xsk_socket *xsk) ctx = xsk->ctx; umem = ctx->umem; - if (ctx->prog_fd != -1) { + + xsk_put_ctx(ctx, true); + + if (!ctx->refcount) { xsk_delete_bpf_maps(xsk); close(ctx->prog_fd); } @@ -948,8 +949,6 @@ void xsk_socket__delete(struct xsk_socket *xsk) } } - xsk_put_ctx(ctx, true); - umem->refcount--; /* Do not close an fd that also has an associated umem connected * to it. -- 2.35.1