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linux-next/drivers/target/target_core_ua.c
Joern Engel 33940d0993 target: encapsulate smp_mb__after_atomic() 
The target code has a rather generous helping of smp_mb__after_atomic()
throughout the code base.  Most atomic operations were followed by one
and none were preceded by smp_mb__before_atomic(), nor accompanied by a
comment explaining the need for a barrier.

Instead of trying to prove for every case whether or not it is needed,
this patch introduces atomic_inc_mb() and atomic_dec_mb(), which
explicitly include the memory barriers before and after the atomic
operation.  For now they are defined in a target header, although they
could be of general use.

Most of the existing atomic/mb combinations were replaced by the new
helpers.  In a few cases the atomic was sandwiched in
spin_lock/spin_unlock and I simply removed the barrier.

I suspect that in most cases the correct conversion would have been to
drop the barrier.  I also suspect that a few cases exist where a) the
barrier was necessary and b) a second barrier before the atomic would
have been necessary and got added by this patch.

Signed-off-by: Joern Engel <joern@logfs.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01 14:39:06 -07:00

320 lines
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/*******************************************************************************
* Filename: target_core_ua.c
*
* This file contains logic for SPC-3 Unit Attention emulation
*
* (c) Copyright 2009-2013 Datera, Inc.
*
* Nicholas A. Bellinger <nab@kernel.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
******************************************************************************/
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/target_core_configfs.h>
#include "target_core_internal.h"
#include "target_core_alua.h"
#include "target_core_pr.h"
#include "target_core_ua.h"
sense_reason_t
target_scsi3_ua_check(struct se_cmd *cmd)
{
struct se_dev_entry *deve;
struct se_session *sess = cmd->se_sess;
struct se_node_acl *nacl;
if (!sess)
return 0;
nacl = sess->se_node_acl;
if (!nacl)
return 0;
deve = nacl->device_list[cmd->orig_fe_lun];
if (!atomic_read(&deve->ua_count))
return 0;
/*
* From sam4r14, section 5.14 Unit attention condition:
*
* a) if an INQUIRY command enters the enabled command state, the
* device server shall process the INQUIRY command and shall neither
* report nor clear any unit attention condition;
* b) if a REPORT LUNS command enters the enabled command state, the
* device server shall process the REPORT LUNS command and shall not
* report any unit attention condition;
* e) if a REQUEST SENSE command enters the enabled command state while
* a unit attention condition exists for the SCSI initiator port
* associated with the I_T nexus on which the REQUEST SENSE command
* was received, then the device server shall process the command
* and either:
*/
switch (cmd->t_task_cdb[0]) {
case INQUIRY:
case REPORT_LUNS:
case REQUEST_SENSE:
return 0;
default:
return TCM_CHECK_CONDITION_UNIT_ATTENTION;
}
}
int core_scsi3_ua_allocate(
struct se_node_acl *nacl,
u32 unpacked_lun,
u8 asc,
u8 ascq)
{
struct se_dev_entry *deve;
struct se_ua *ua, *ua_p, *ua_tmp;
/*
* PASSTHROUGH OPS
*/
if (!nacl)
return -EINVAL;
ua = kmem_cache_zalloc(se_ua_cache, GFP_ATOMIC);
if (!ua) {
pr_err("Unable to allocate struct se_ua\n");
return -ENOMEM;
}
INIT_LIST_HEAD(&ua->ua_nacl_list);
ua->ua_nacl = nacl;
ua->ua_asc = asc;
ua->ua_ascq = ascq;
spin_lock_irq(&nacl->device_list_lock);
deve = nacl->device_list[unpacked_lun];
spin_lock(&deve->ua_lock);
list_for_each_entry_safe(ua_p, ua_tmp, &deve->ua_list, ua_nacl_list) {
/*
* Do not report the same UNIT ATTENTION twice..
*/
if ((ua_p->ua_asc == asc) && (ua_p->ua_ascq == ascq)) {
spin_unlock(&deve->ua_lock);
spin_unlock_irq(&nacl->device_list_lock);
kmem_cache_free(se_ua_cache, ua);
return 0;
}
/*
* Attach the highest priority Unit Attention to
* the head of the list following sam4r14,
* Section 5.14 Unit Attention Condition:
*
* POWER ON, RESET, OR BUS DEVICE RESET OCCURRED highest
* POWER ON OCCURRED or
* DEVICE INTERNAL RESET
* SCSI BUS RESET OCCURRED or
* MICROCODE HAS BEEN CHANGED or
* protocol specific
* BUS DEVICE RESET FUNCTION OCCURRED
* I_T NEXUS LOSS OCCURRED
* COMMANDS CLEARED BY POWER LOSS NOTIFICATION
* all others Lowest
*
* Each of the ASCQ codes listed above are defined in
* the 29h ASC family, see spc4r17 Table D.1
*/
if (ua_p->ua_asc == 0x29) {
if ((asc == 0x29) && (ascq > ua_p->ua_ascq))
list_add(&ua->ua_nacl_list,
&deve->ua_list);
else
list_add_tail(&ua->ua_nacl_list,
&deve->ua_list);
} else if (ua_p->ua_asc == 0x2a) {
/*
* Incoming Family 29h ASCQ codes will override
* Family 2AHh ASCQ codes for Unit Attention condition.
*/
if ((asc == 0x29) || (ascq > ua_p->ua_asc))
list_add(&ua->ua_nacl_list,
&deve->ua_list);
else
list_add_tail(&ua->ua_nacl_list,
&deve->ua_list);
} else
list_add_tail(&ua->ua_nacl_list,
&deve->ua_list);
spin_unlock(&deve->ua_lock);
spin_unlock_irq(&nacl->device_list_lock);
atomic_inc_mb(&deve->ua_count);
return 0;
}
list_add_tail(&ua->ua_nacl_list, &deve->ua_list);
spin_unlock(&deve->ua_lock);
spin_unlock_irq(&nacl->device_list_lock);
pr_debug("[%s]: Allocated UNIT ATTENTION, mapped LUN: %u, ASC:"
" 0x%02x, ASCQ: 0x%02x\n",
nacl->se_tpg->se_tpg_tfo->get_fabric_name(), unpacked_lun,
asc, ascq);
atomic_inc_mb(&deve->ua_count);
return 0;
}
void core_scsi3_ua_release_all(
struct se_dev_entry *deve)
{
struct se_ua *ua, *ua_p;
spin_lock(&deve->ua_lock);
list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
list_del(&ua->ua_nacl_list);
kmem_cache_free(se_ua_cache, ua);
atomic_dec_mb(&deve->ua_count);
}
spin_unlock(&deve->ua_lock);
}
void core_scsi3_ua_for_check_condition(
struct se_cmd *cmd,
u8 *asc,
u8 *ascq)
{
struct se_device *dev = cmd->se_dev;
struct se_dev_entry *deve;
struct se_session *sess = cmd->se_sess;
struct se_node_acl *nacl;
struct se_ua *ua = NULL, *ua_p;
int head = 1;
if (!sess)
return;
nacl = sess->se_node_acl;
if (!nacl)
return;
spin_lock_irq(&nacl->device_list_lock);
deve = nacl->device_list[cmd->orig_fe_lun];
if (!atomic_read(&deve->ua_count)) {
spin_unlock_irq(&nacl->device_list_lock);
return;
}
/*
* The highest priority Unit Attentions are placed at the head of the
* struct se_dev_entry->ua_list, and will be returned in CHECK_CONDITION +
* sense data for the received CDB.
*/
spin_lock(&deve->ua_lock);
list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
/*
* For ua_intlck_ctrl code not equal to 00b, only report the
* highest priority UNIT_ATTENTION and ASC/ASCQ without
* clearing it.
*/
if (dev->dev_attrib.emulate_ua_intlck_ctrl != 0) {
*asc = ua->ua_asc;
*ascq = ua->ua_ascq;
break;
}
/*
* Otherwise for the default 00b, release the UNIT ATTENTION
* condition. Return the ASC/ASCQ of the highest priority UA
* (head of the list) in the outgoing CHECK_CONDITION + sense.
*/
if (head) {
*asc = ua->ua_asc;
*ascq = ua->ua_ascq;
head = 0;
}
list_del(&ua->ua_nacl_list);
kmem_cache_free(se_ua_cache, ua);
atomic_dec_mb(&deve->ua_count);
}
spin_unlock(&deve->ua_lock);
spin_unlock_irq(&nacl->device_list_lock);
pr_debug("[%s]: %s UNIT ATTENTION condition with"
" INTLCK_CTRL: %d, mapped LUN: %u, got CDB: 0x%02x"
" reported ASC: 0x%02x, ASCQ: 0x%02x\n",
nacl->se_tpg->se_tpg_tfo->get_fabric_name(),
(dev->dev_attrib.emulate_ua_intlck_ctrl != 0) ? "Reporting" :
"Releasing", dev->dev_attrib.emulate_ua_intlck_ctrl,
cmd->orig_fe_lun, cmd->t_task_cdb[0], *asc, *ascq);
}
int core_scsi3_ua_clear_for_request_sense(
struct se_cmd *cmd,
u8 *asc,
u8 *ascq)
{
struct se_dev_entry *deve;
struct se_session *sess = cmd->se_sess;
struct se_node_acl *nacl;
struct se_ua *ua = NULL, *ua_p;
int head = 1;
if (!sess)
return -EINVAL;
nacl = sess->se_node_acl;
if (!nacl)
return -EINVAL;
spin_lock_irq(&nacl->device_list_lock);
deve = nacl->device_list[cmd->orig_fe_lun];
if (!atomic_read(&deve->ua_count)) {
spin_unlock_irq(&nacl->device_list_lock);
return -EPERM;
}
/*
* The highest priority Unit Attentions are placed at the head of the
* struct se_dev_entry->ua_list. The First (and hence highest priority)
* ASC/ASCQ will be returned in REQUEST_SENSE payload data for the
* matching struct se_lun.
*
* Once the returning ASC/ASCQ values are set, we go ahead and
* release all of the Unit Attention conditions for the associated
* struct se_lun.
*/
spin_lock(&deve->ua_lock);
list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
if (head) {
*asc = ua->ua_asc;
*ascq = ua->ua_ascq;
head = 0;
}
list_del(&ua->ua_nacl_list);
kmem_cache_free(se_ua_cache, ua);
atomic_dec_mb(&deve->ua_count);
}
spin_unlock(&deve->ua_lock);
spin_unlock_irq(&nacl->device_list_lock);
pr_debug("[%s]: Released UNIT ATTENTION condition, mapped"
" LUN: %u, got REQUEST_SENSE reported ASC: 0x%02x,"
" ASCQ: 0x%02x\n", nacl->se_tpg->se_tpg_tfo->get_fabric_name(),
cmd->orig_fe_lun, *asc, *ascq);
return (head) ? -EPERM : 0;
}
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