5e8e6b4b3a
This patch fixes a >= v3.10 regression bug with mutex_trylock() usage within iscsit_increment_maxcmdsn(), that was originally added to allow for a special case where ->cmdsn_mutex was already held from the iscsit_execute_cmd() exception path for ib_isert. When !mutex_trylock() was occuring under contention during normal RX/TX process context codepaths, the bug was manifesting itself as the following protocol error: Received CmdSN: 0x000fcbb7 is greater than MaxCmdSN: 0x000fcbb6, protocol error. Received CmdSN: 0x000fcbb8 is greater than MaxCmdSN: 0x000fcbb6, protocol error. This patch simply avoids the direct ib_isert callback in lio_queue_status() for the special iscsi_execute_cmd() exception cases, that allows the problematic mutex_trylock() usage in iscsit_increment_maxcmdsn() to go away. Reported-by: Moussa Ba <moussaba@micron.com> Tested-by: Moussa Ba <moussaba@micron.com> Cc: <stable@vger.kernel.org> # v3.10+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
66 lines
2.2 KiB
C
66 lines
2.2 KiB
C
/*******************************************************************************
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* This file contains the iSCSI Virtual Device and Disk Transport
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* agnostic related functions.
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*
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* (c) Copyright 2007-2013 Datera, Inc.
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*
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* Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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******************************************************************************/
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#include <scsi/scsi_device.h>
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#include <target/target_core_base.h>
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#include <target/target_core_fabric.h>
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#include "iscsi_target_core.h"
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#include "iscsi_target_device.h"
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#include "iscsi_target_tpg.h"
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#include "iscsi_target_util.h"
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void iscsit_determine_maxcmdsn(struct iscsi_session *sess)
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{
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struct se_node_acl *se_nacl;
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/*
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* This is a discovery session, the single queue slot was already
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* assigned in iscsi_login_zero_tsih(). Since only Logout and
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* Text Opcodes are allowed during discovery we do not have to worry
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* about the HBA's queue depth here.
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*/
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if (sess->sess_ops->SessionType)
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return;
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se_nacl = sess->se_sess->se_node_acl;
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/*
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* This is a normal session, set the Session's CmdSN window to the
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* struct se_node_acl->queue_depth. The value in struct se_node_acl->queue_depth
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* has already been validated as a legal value in
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* core_set_queue_depth_for_node().
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*/
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sess->cmdsn_window = se_nacl->queue_depth;
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sess->max_cmd_sn = (sess->max_cmd_sn + se_nacl->queue_depth) - 1;
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}
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void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess)
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{
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if (cmd->immediate_cmd || cmd->maxcmdsn_inc)
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return;
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cmd->maxcmdsn_inc = 1;
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mutex_lock(&sess->cmdsn_mutex);
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sess->max_cmd_sn += 1;
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pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn);
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mutex_unlock(&sess->cmdsn_mutex);
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}
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EXPORT_SYMBOL(iscsit_increment_maxcmdsn);
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