From patchwork Thu Sep 28 13:19:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 1840828 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=PJ8yC15S; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4RxDlW1DGJz1yp0 for ; Thu, 28 Sep 2023 23:26:31 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qlqww-0003n5-HL; Thu, 28 Sep 2023 09:21:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qlqwW-0003Vw-0y for qemu-devel@nongnu.org; Thu, 28 Sep 2023 09:20:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qlqwN-0008Ef-Jt for qemu-devel@nongnu.org; Thu, 28 Sep 2023 09:20:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695907226; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BU0uqGbP8qq4nNLIZgnbAmU0nErX6Kb3gxdo8hQggZ8=; b=PJ8yC15SotzTn80zoNi+LKjQUBijp0S29AgtJ8boeWUGyDtPgPKy69DwfaZ+EKAR002Pmd ALoI78VM5xIw6bkFBA3+QFdkdXl1TdqCLKMa2KVHqcHfrHqRhcgWlFeRSDvHt8hHaIksUz 1+vdSDvTdaL0caq2oOzkhU0p5FpYY/o= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-164-YQtk4SzeML6LczlCsMGKvg-1; Thu, 28 Sep 2023 09:20:23 -0400 X-MC-Unique: YQtk4SzeML6LczlCsMGKvg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 32961381459B; Thu, 28 Sep 2023 13:20:23 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E8D27167F8; Thu, 28 Sep 2023 13:20:22 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id EF71921E691B; Thu, 28 Sep 2023 15:20:19 +0200 (CEST) From: Markus Armbruster To: qemu-devel@nongnu.org Cc: quintela@redhat.com, peterx@redhat.com, leobras@redhat.com, farosas@suse.de, lizhijian@fujitsu.com, eblake@redhat.com Subject: [PATCH v2 16/53] migration/rdma: Fix or document problematic uses of errno Date: Thu, 28 Sep 2023 15:19:42 +0200 Message-ID: <20230928132019.2544702-17-armbru@redhat.com> In-Reply-To: <20230928132019.2544702-1-armbru@redhat.com> References: <20230928132019.2544702-1-armbru@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org We use errno after calling Libibverbs functions that are not documented to set errno (manual page does not mention errno), or where the documentation is unclear ("returns [...] the value of errno on failure"). While this could be read as "sets errno and returns it", a glance at the source code[*] kills that hope: static inline int ibv_post_send(struct ibv_qp *qp, struct ibv_send_wr *wr, struct ibv_send_wr **bad_wr) { return qp->context->ops.post_send(qp, wr, bad_wr); } The callback can be static int mana_post_send(struct ibv_qp *ibqp, struct ibv_send_wr *wr, struct ibv_send_wr **bad) { /* This version of driver supports RAW QP only. * Posting WR is done directly in the application. */ return EOPNOTSUPP; } Neither of them touches errno. One of these errno uses is easy to fix, so do that now. Several more will go away later in the series; add temporary FIXME commments. Three will remain; add TODO comments. TODO, not FIXME, because the bug might be in Libibverbs documentation. [*] https://github.com/linux-rdma/rdma-core.git commit 55fa316b4b18f258d8ac1ceb4aa5a7a35b094dcf Signed-off-by: Markus Armbruster Reviewed-by: Juan Quintela Reviewed-by: Li Zhijian --- migration/rdma.c | 45 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/migration/rdma.c b/migration/rdma.c index 28097ce604..bba8c99fa9 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -853,6 +853,12 @@ static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp) for (x = 0; x < num_devices; x++) { verbs = ibv_open_device(dev_list[x]); + /* + * ibv_open_device() is not documented to set errno. If + * it does, it's somebody else's doc bug. If it doesn't, + * the use of errno below is wrong. + * TODO Find out whether ibv_open_device() sets errno. + */ if (!verbs) { if (errno == EPERM) { continue; @@ -1162,11 +1168,7 @@ static void qemu_rdma_advise_prefetch_mr(struct ibv_pd *pd, uint64_t addr, ret = ibv_advise_mr(pd, advice, IBV_ADVISE_MR_FLAG_FLUSH, &sg_list, 1); /* ignore the error */ - if (ret) { - trace_qemu_rdma_advise_mr(name, len, addr, strerror(errno)); - } else { - trace_qemu_rdma_advise_mr(name, len, addr, "successed"); - } + trace_qemu_rdma_advise_mr(name, len, addr, strerror(ret)); #endif } @@ -1183,7 +1185,12 @@ static int qemu_rdma_reg_whole_ram_blocks(RDMAContext *rdma) local->block[i].local_host_addr, local->block[i].length, access ); - + /* + * ibv_reg_mr() is not documented to set errno. If it does, + * it's somebody else's doc bug. If it doesn't, the use of + * errno below is wrong. + * TODO Find out whether ibv_reg_mr() sets errno. + */ if (!local->block[i].mr && errno == ENOTSUP && rdma_support_odp(rdma->verbs)) { access |= IBV_ACCESS_ON_DEMAND; @@ -1291,6 +1298,12 @@ static int qemu_rdma_register_and_get_keys(RDMAContext *rdma, trace_qemu_rdma_register_and_get_keys(len, chunk_start); block->pmr[chunk] = ibv_reg_mr(rdma->pd, chunk_start, len, access); + /* + * ibv_reg_mr() is not documented to set errno. If it does, + * it's somebody else's doc bug. If it doesn't, the use of + * errno below is wrong. + * TODO Find out whether ibv_reg_mr() sets errno. + */ if (!block->pmr[chunk] && errno == ENOTSUP && rdma_support_odp(rdma->verbs)) { access |= IBV_ACCESS_ON_DEMAND; @@ -1408,6 +1421,11 @@ static int qemu_rdma_unregister_waiting(RDMAContext *rdma) block->remote_keys[chunk] = 0; if (ret != 0) { + /* + * FIXME perror() is problematic, bcause ibv_dereg_mr() is + * not documented to set errno. Will go away later in + * this series. + */ perror("unregistration chunk failed"); return -ret; } @@ -1658,6 +1676,11 @@ static int qemu_rdma_block_for_wrid(RDMAContext *rdma, ret = ibv_get_cq_event(ch, &cq, &cq_ctx); if (ret) { + /* + * FIXME perror() is problematic, because ibv_reg_mr() is + * not documented to set errno. Will go away later in + * this series. + */ perror("ibv_get_cq_event"); goto err_block_for_wrid; } @@ -2199,6 +2222,11 @@ retry: goto retry; } else if (ret > 0) { + /* + * FIXME perror() is problematic, because whether + * ibv_post_send() sets errno is unclear. Will go away later + * in this series. + */ perror("rdma migration: post rdma write failed"); return -ret; } @@ -2559,6 +2587,11 @@ static int qemu_rdma_connect(RDMAContext *rdma, bool return_path, ret = rdma_get_cm_event(rdma->channel, &cm_event); } if (ret) { + /* + * FIXME perror() is wrong, because + * qemu_get_cm_event_timeout() can fail without setting errno. + * Will go away later in this series. + */ perror("rdma_get_cm_event after rdma_connect"); ERROR(errp, "connecting to destination!"); goto err_rdma_source_connect;