From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:40028 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754587AbeDJWac (ORCPT ); Tue, 10 Apr 2018 18:30:32 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Christie , Nicholas Bellinger , Sasha Levin Subject: [PATCH 4.15 105/168] tcmu: release blocks for partially setup cmds Date: Wed, 11 Apr 2018 00:24:07 +0200 Message-Id: <20180410212804.710990639@linuxfoundation.org> In-Reply-To: <20180410212800.144079021@linuxfoundation.org> References: <20180410212800.144079021@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Christie [ Upstream commit 810b8153c4243d2012a6ec002ddd3bbc9a9ae8c2 ] If we cannot setup a cmd because we run out of ring space or global pages release the blocks before sleeping. This prevents a deadlock where dev0 has waiting_blocks set and needs N blocks, but dev1 to devX have each allocated N / X blocks and also hit the global block limit so they went to sleep. find_free_blocks is not able to take the sleeping dev's blocks becaause their waiting_blocks is set and even if it was not the block returned by find_last_bit could equal dbi_max. The latter will probably never happen because DATA_BLOCK_BITS is so high but in the next patches DATA_BLOCK_BITS and TCMU_GLOBAL_MAX_BLOCKS will be settable so it might be lower and could happen. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/target/target_core_user.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -805,6 +805,13 @@ tcmu_queue_cmd_ring(struct tcmu_cmd *tcm int ret; DEFINE_WAIT(__wait); + /* + * Don't leave commands partially setup because the unmap + * thread might need the blocks to make forward progress. + */ + tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cur); + tcmu_cmd_reset_dbi_cur(tcmu_cmd); + prepare_to_wait(&udev->wait_cmdr, &__wait, TASK_INTERRUPTIBLE); pr_debug("sleeping for ring space\n");