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linux/drivers/target/target_core_internal.h
Mike Christie ed1227e080 scsi: target: Fix ordered tag handling 
This patch fixes the following bugs:

1. If there are multiple ordered cmds queued and multiple simple cmds
   completing, target_restart_delayed_cmds() could be called on different
   CPUs and each instance could start a ordered cmd. They could then run in
   different orders than they were queued.

2. target_restart_delayed_cmds() and target_handle_task_attr() can race
   where:

   1. target_handle_task_attr() has passed the simple_cmds == 0 check.

   2. transport_complete_task_attr() then decrements simple_cmds to 0.

   3. transport_complete_task_attr() runs target_restart_delayed_cmds() and
      it does not see any cmds on the delayed_cmd_list.

   4. target_handle_task_attr() adds the cmd to the delayed_cmd_list.

   The cmd will then end up timing out.

3. If we are sent > 1 ordered cmds and simple_cmds == 0, we can execute
   them out of order, because target_handle_task_attr() will hit that
   simple_cmds check first and return false for all ordered cmds sent.

4. We run target_restart_delayed_cmds() after every cmd completion, so if
   there is more than 1 simple cmd running, we start executing ordered cmds
   after that first cmd instead of waiting for all of them to complete.

5. Ordered cmds are not supposed to start until HEAD OF QUEUE and all older
   cmds have completed, and not just simple.

6. It's not a bug but it doesn't make sense to take the delayed_cmd_lock
   for every cmd completion when ordered cmds are almost never used. Just
   replacing that lock with an atomic increases IOPs by up to 10% when
   completions are spread over multiple CPUs and there are multiple
   sessions/ mqs/thread accessing the same device.

This patch moves the queued delayed handling to a per device work to
serialze the cmd executions for each device and adds a new counter to track
HEAD_OF_QUEUE and SIMPLE cmds. We can then check the new counter to
determine when to run the work on the completion path.

Link: https://lore.kernel.org/r/20210930020422.92578-3-michael.christie@oracle.com
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2021-10-18 22:38:35 -04:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef TARGET_CORE_INTERNAL_H
#define TARGET_CORE_INTERNAL_H
#include <linux/configfs.h>
#include <linux/list.h>
#include <linux/types.h>
#include <target/target_core_base.h>
#define TARGET_CORE_NAME_MAX_LEN 64
#define TARGET_FABRIC_NAME_SIZE 32
struct target_backend {
struct list_head list;
const struct target_backend_ops *ops;
struct config_item_type tb_dev_cit;
struct config_item_type tb_dev_attrib_cit;
struct config_item_type tb_dev_action_cit;
struct config_item_type tb_dev_pr_cit;
struct config_item_type tb_dev_wwn_cit;
struct config_item_type tb_dev_alua_tg_pt_gps_cit;
struct config_item_type tb_dev_stat_cit;
};
struct target_fabric_configfs {
atomic_t tf_access_cnt;
struct list_head tf_list;
struct config_group tf_group;
struct config_group tf_disc_group;
const struct target_core_fabric_ops *tf_ops;
struct config_item_type tf_discovery_cit;
struct config_item_type tf_wwn_cit;
struct config_item_type tf_wwn_fabric_stats_cit;
struct config_item_type tf_wwn_param_cit;
struct config_item_type tf_tpg_cit;
struct config_item_type tf_tpg_base_cit;
struct config_item_type tf_tpg_lun_cit;
struct config_item_type tf_tpg_port_cit;
struct config_item_type tf_tpg_port_stat_cit;
struct config_item_type tf_tpg_np_cit;
struct config_item_type tf_tpg_np_base_cit;
struct config_item_type tf_tpg_attrib_cit;
struct config_item_type tf_tpg_auth_cit;
struct config_item_type tf_tpg_param_cit;
struct config_item_type tf_tpg_nacl_cit;
struct config_item_type tf_tpg_nacl_base_cit;
struct config_item_type tf_tpg_nacl_attrib_cit;
struct config_item_type tf_tpg_nacl_auth_cit;
struct config_item_type tf_tpg_nacl_param_cit;
struct config_item_type tf_tpg_nacl_stat_cit;
struct config_item_type tf_tpg_mappedlun_cit;
struct config_item_type tf_tpg_mappedlun_stat_cit;
};
/* target_core_alua.c */
extern struct t10_alua_lu_gp *default_lu_gp;
/* target_core_device.c */
int core_alloc_rtpi(struct se_lun *lun, struct se_device *dev);
struct se_dev_entry *core_get_se_deve_from_rtpi(struct se_node_acl *, u16);
void target_pr_kref_release(struct kref *);
void core_free_device_list_for_node(struct se_node_acl *,
struct se_portal_group *);
void core_update_device_list_access(u64, bool, struct se_node_acl *);
struct se_dev_entry *target_nacl_find_deve(struct se_node_acl *, u64);
int core_enable_device_list_for_node(struct se_lun *, struct se_lun_acl *,
u64, bool, struct se_node_acl *, struct se_portal_group *);
void core_disable_device_list_for_node(struct se_lun *, struct se_dev_entry *,
struct se_node_acl *, struct se_portal_group *);
void core_clear_lun_from_tpg(struct se_lun *, struct se_portal_group *);
int core_dev_add_lun(struct se_portal_group *, struct se_device *,
struct se_lun *lun);
void core_dev_del_lun(struct se_portal_group *, struct se_lun *);
struct se_lun_acl *core_dev_init_initiator_node_lun_acl(struct se_portal_group *,
struct se_node_acl *, u64, int *);
int core_dev_add_initiator_node_lun_acl(struct se_portal_group *,
struct se_lun_acl *, struct se_lun *lun, bool);
int core_dev_del_initiator_node_lun_acl(struct se_lun *,
struct se_lun_acl *);
void core_dev_free_initiator_node_lun_acl(struct se_portal_group *,
struct se_lun_acl *lacl);
int core_dev_setup_virtual_lun0(void);
void core_dev_release_virtual_lun0(void);
struct se_device *target_alloc_device(struct se_hba *hba, const char *name);
int target_configure_device(struct se_device *dev);
void target_free_device(struct se_device *);
int target_for_each_device(int (*fn)(struct se_device *dev, void *data),
void *data);
/* target_core_configfs.c */
extern struct configfs_item_operations target_core_dev_item_ops;
void target_setup_backend_cits(struct target_backend *);
/* target_core_fabric_configfs.c */
int target_fabric_setup_cits(struct target_fabric_configfs *);
/* target_core_fabric_lib.c */
int target_get_pr_transport_id_len(struct se_node_acl *nacl,
struct t10_pr_registration *pr_reg, int *format_code);
int target_get_pr_transport_id(struct se_node_acl *nacl,
struct t10_pr_registration *pr_reg, int *format_code,
unsigned char *buf);
const char *target_parse_pr_out_transport_id(struct se_portal_group *tpg,
char *buf, u32 *out_tid_len, char **port_nexus_ptr);
/* target_core_hba.c */
struct se_hba *core_alloc_hba(const char *, u32, u32);
int core_delete_hba(struct se_hba *);
/* target_core_tmr.c */
void core_tmr_abort_task(struct se_device *, struct se_tmr_req *,
struct se_session *);
int core_tmr_lun_reset(struct se_device *, struct se_tmr_req *,
struct list_head *, struct se_cmd *);
/* target_core_tpg.c */
extern struct se_device *g_lun0_dev;
struct se_node_acl *__core_tpg_get_initiator_node_acl(struct se_portal_group *tpg,
const char *);
void core_tpg_add_node_to_devs(struct se_node_acl *, struct se_portal_group *,
struct se_lun *);
void core_tpg_wait_for_nacl_pr_ref(struct se_node_acl *);
struct se_lun *core_tpg_alloc_lun(struct se_portal_group *, u64);
int core_tpg_add_lun(struct se_portal_group *, struct se_lun *,
bool, struct se_device *);
void core_tpg_remove_lun(struct se_portal_group *, struct se_lun *);
struct se_node_acl *core_tpg_add_initiator_node_acl(struct se_portal_group *tpg,
const char *initiatorname);
void core_tpg_del_initiator_node_acl(struct se_node_acl *acl);
/* target_core_transport.c */
extern struct kmem_cache *se_tmr_req_cache;
int init_se_kmem_caches(void);
void release_se_kmem_caches(void);
u32 scsi_get_new_index(scsi_index_t);
void transport_subsystem_check_init(void);
void transport_uninit_session(struct se_session *);
unsigned char *transport_dump_cmd_direction(struct se_cmd *);
void transport_dump_dev_state(struct se_device *, char *, int *);
void transport_dump_dev_info(struct se_device *, struct se_lun *,
unsigned long long, char *, int *);
void transport_dump_vpd_proto_id(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int);
void transport_clear_lun_ref(struct se_lun *);
sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size);
void target_qf_do_work(struct work_struct *work);
void target_do_delayed_work(struct work_struct *work);
bool target_check_wce(struct se_device *dev);
bool target_check_fua(struct se_device *dev);
void __target_execute_cmd(struct se_cmd *, bool);
void target_queued_submit_work(struct work_struct *work);
/* target_core_stat.c */
void target_stat_setup_dev_default_groups(struct se_device *);
void target_stat_setup_port_default_groups(struct se_lun *);
void target_stat_setup_mappedlun_default_groups(struct se_lun_acl *);
/* target_core_xcopy.c */
extern struct se_portal_group xcopy_pt_tpg;
/* target_core_configfs.c */
#define DB_ROOT_LEN 4096
#define DB_ROOT_DEFAULT "/var/target"
#define DB_ROOT_PREFERRED "/etc/target"
extern char db_root[];
#endif /* TARGET_CORE_INTERNAL_H */
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