From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 B3DBA227E8C for ; Wed, 16 Apr 2025 03:55:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744775709; cv=none; b=YnUMCUKB4MJ5DfKgg2b3+KXEJB1nQIm0b9HFHK3Tr1HnwQn5sgnbmp+oua7SAq9zyc9Hg4Y2c0q2TiS7QXkbUWWv54gQYNQT0920PnMkP78E218f0oZMjX0Gy4royXZqmCojP5YYAAEjF6+XV8gtIa+e4vYiAdWUWQdLLf+S6hw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744775709; c=relaxed/simple; bh=v+FFiD/papFMMYuDyB2MUsGMRYMWgJFFkuiMYhbZu2k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KAjvflZbtnAiTgCvctVICJOv2/EYN9yncCqD1WOZ3ArbwAo6Tzl+nQ01xKcl4xf1YjL+d3oKoO5UOLqL2HuyRVZCZPPB5x5oNUEa4f+wEeNbBgt9mLM4mGw70QL/Q+6VVW/9xzxKqH0eiA2WbB2+z1CZvAunrqiemYPLdu5DcnA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ayST7ExB; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ayST7ExB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744775703; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KILrcwXdz+888fnlHOLvo5Tmh82UsUl/qqfsiKb1wL0=; b=ayST7ExBg3a7eE3sg6A/VxOeqExjd9qiiO+1GeWV9h2wfVxZYFhSShnLtfJXo8mx2CgdwM 7O7uvEN77kGkU7DdcD9V9AkJWCjYv4d0WSywYIwcfalH8l10NbwgYBV7PRlXrqcgibtWnQ /c6q21lUSBPsQz8o3M2LtL15g8INZeo= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-340-DrbMEXNIO6i_pSa7HP0g9A-1; Tue, 15 Apr 2025 23:55:00 -0400 X-MC-Unique: DrbMEXNIO6i_pSa7HP0g9A-1 X-Mimecast-MFC-AGG-ID: DrbMEXNIO6i_pSa7HP0g9A_1744775699 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CFF7419560BB; Wed, 16 Apr 2025 03:54:58 +0000 (UTC) Received: from localhost (unknown [10.72.116.72]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 8EEC5180B489; Wed, 16 Apr 2025 03:54:57 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: Caleb Sander Mateos , Uday Shankar , Ming Lei Subject: [PATCH V2 1/8] ublk: properly serialize all FETCH_REQs Date: Wed, 16 Apr 2025 11:54:35 +0800 Message-ID: <20250416035444.99569-2-ming.lei@redhat.com> In-Reply-To: <20250416035444.99569-1-ming.lei@redhat.com> References: <20250416035444.99569-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 From: Uday Shankar Most uring_cmds issued against ublk character devices are serialized because each command affects only one queue, and there is an early check which only allows a single task (the queue's ubq_daemon) to issue uring_cmds against that queue. However, this mechanism does not work for FETCH_REQs, since they are expected before ubq_daemon is set. Since FETCH_REQs are only used at initialization and not in the fast path, serialize them using the per-ublk-device mutex. This fixes a number of data races that were previously possible if a badly behaved ublk server decided to issue multiple FETCH_REQs against the same qid/tag concurrently. Reported-by: Caleb Sander Mateos Signed-off-by: Uday Shankar Signed-off-by: Ming Lei --- drivers/block/ublk_drv.c | 77 +++++++++++++++++++++++++--------------- 1 file changed, 49 insertions(+), 28 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index cdb1543fa4a9..bf47f9cb8329 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1832,8 +1832,8 @@ static void ublk_nosrv_work(struct work_struct *work) /* device can only be started after all IOs are ready */ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq) + __must_hold(&ub->mutex) { - mutex_lock(&ub->mutex); ubq->nr_io_ready++; if (ublk_queue_ready(ubq)) { ubq->ubq_daemon = current; @@ -1845,7 +1845,6 @@ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq) } if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues) complete_all(&ub->completion); - mutex_unlock(&ub->mutex); } static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id, @@ -1929,6 +1928,52 @@ static int ublk_unregister_io_buf(struct io_uring_cmd *cmd, return io_buffer_unregister_bvec(cmd, index, issue_flags); } +static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq, + struct ublk_io *io, __u64 buf_addr) +{ + struct ublk_device *ub = ubq->dev; + int ret = 0; + + /* + * When handling FETCH command for setting up ublk uring queue, + * ub->mutex is the innermost lock, and we won't block for handling + * FETCH, so it is fine even for IO_URING_F_NONBLOCK. + */ + mutex_lock(&ub->mutex); + /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */ + if (ublk_queue_ready(ubq)) { + ret = -EBUSY; + goto out; + } + + /* allow each command to be FETCHed at most once */ + if (io->flags & UBLK_IO_FLAG_ACTIVE) { + ret = -EINVAL; + goto out; + } + + WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV); + + if (ublk_need_map_io(ubq)) { + /* + * FETCH_RQ has to provide IO buffer if NEED GET + * DATA is not enabled + */ + if (!buf_addr && !ublk_need_get_data(ubq)) + goto out; + } else if (buf_addr) { + /* User copy requires addr to be unset */ + ret = -EINVAL; + goto out; + } + + ublk_fill_io_cmd(io, cmd, buf_addr); + ublk_mark_io_ready(ub, ubq); +out: + mutex_unlock(&ub->mutex); + return ret; +} + static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags, const struct ublksrv_io_cmd *ub_cmd) @@ -1985,33 +2030,9 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd, case UBLK_IO_UNREGISTER_IO_BUF: return ublk_unregister_io_buf(cmd, ub_cmd->addr, issue_flags); case UBLK_IO_FETCH_REQ: - /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */ - if (ublk_queue_ready(ubq)) { - ret = -EBUSY; - goto out; - } - /* - * The io is being handled by server, so COMMIT_RQ is expected - * instead of FETCH_REQ - */ - if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV) - goto out; - - if (ublk_need_map_io(ubq)) { - /* - * FETCH_RQ has to provide IO buffer if NEED GET - * DATA is not enabled - */ - if (!ub_cmd->addr && !ublk_need_get_data(ubq)) - goto out; - } else if (ub_cmd->addr) { - /* User copy requires addr to be unset */ - ret = -EINVAL; + ret = ublk_fetch(cmd, ubq, io, ub_cmd->addr); + if (ret) goto out; - } - - ublk_fill_io_cmd(io, cmd, ub_cmd->addr); - ublk_mark_io_ready(ub, ubq); break; case UBLK_IO_COMMIT_AND_FETCH_REQ: req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag); -- 2.47.0