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linux/drivers/scsi/scsi_priv.h
Ming Lei 4373534a98 scsi: core: Move scsi_host_busy() out of host lock for waking up EH handler 
Inside scsi_eh_wakeup(), scsi_host_busy() is called & checked with host
lock every time for deciding if error handler kthread needs to be waken up.

This can be too heavy in case of recovery, such as:

 - N hardware queues

 - queue depth is M for each hardware queue

 - each scsi_host_busy() iterates over (N * M) tag/requests

If recovery is triggered in case that all requests are in-flight, each
scsi_eh_wakeup() is strictly serialized, when scsi_eh_wakeup() is called
for the last in-flight request, scsi_host_busy() has been run for (N * M -
1) times, and request has been iterated for (N*M - 1) * (N * M) times.

If both N and M are big enough, hard lockup can be triggered on acquiring
host lock, and it is observed on mpi3mr(128 hw queues, queue depth 8169).

Fix the issue by calling scsi_host_busy() outside the host lock. We don't
need the host lock for getting busy count because host the lock never
covers that.

[mkp: Drop unnecessary 'busy' variables pointed out by Bart]

Cc: Ewan Milne <emilne@redhat.com>
Fixes: 6eb045e092 ("scsi: core: avoid host-wide host_busy counter for scsi_mq")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20240112070000.4161982-1-ming.lei@redhat.com
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Sathya Prakash Veerichetty <safhya.prakash@broadcom.com>
Tested-by: Sathya Prakash Veerichetty <safhya.prakash@broadcom.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2024-01-23 21:21:51 -05:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _SCSI_PRIV_H
#define _SCSI_PRIV_H
#include <linux/device.h>
#include <scsi/scsi_device.h>
#include <linux/sbitmap.h>
struct bsg_device;
struct request_queue;
struct request;
struct scsi_cmnd;
struct scsi_device;
struct scsi_target;
struct scsi_host_template;
struct Scsi_Host;
struct scsi_nl_hdr;
#define SCSI_CMD_RETRIES_NO_LIMIT -1
/*
* Error codes used by scsi-ml internally. These must not be used by drivers.
*/
enum scsi_ml_status {
SCSIML_STAT_OK = 0x00,
SCSIML_STAT_RESV_CONFLICT = 0x01, /* Reservation conflict */
SCSIML_STAT_NOSPC = 0x02, /* Space allocation on the dev failed */
SCSIML_STAT_MED_ERROR = 0x03, /* Medium error */
SCSIML_STAT_TGT_FAILURE = 0x04, /* Permanent target failure */
SCSIML_STAT_DL_TIMEOUT = 0x05, /* Command Duration Limit timeout */
};
static inline u8 scsi_ml_byte(int result)
{
return (result >> 8) & 0xff;
}
/*
* Scsi Error Handler Flags
*/
#define SCSI_EH_ABORT_SCHEDULED 0x0002 /* Abort has been scheduled */
#define SCSI_SENSE_VALID(scmd) \
(((scmd)->sense_buffer[0] & 0x70) == 0x70)
/* hosts.c */
extern int scsi_init_hosts(void);
extern void scsi_exit_hosts(void);
/* scsi.c */
int scsi_init_sense_cache(struct Scsi_Host *shost);
void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd);
#ifdef CONFIG_SCSI_LOGGING
void scsi_log_send(struct scsi_cmnd *cmd);
void scsi_log_completion(struct scsi_cmnd *cmd, int disposition);
#else
static inline void scsi_log_send(struct scsi_cmnd *cmd)
{ };
static inline void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
{ };
#endif
/* scsi_devinfo.c */
/* list of keys for the lists */
enum scsi_devinfo_key {
SCSI_DEVINFO_GLOBAL = 0,
SCSI_DEVINFO_SPI,
};
extern blist_flags_t scsi_get_device_flags(struct scsi_device *sdev,
const unsigned char *vendor,
const unsigned char *model);
extern blist_flags_t scsi_get_device_flags_keyed(struct scsi_device *sdev,
const unsigned char *vendor,
const unsigned char *model,
enum scsi_devinfo_key key);
extern int scsi_dev_info_list_add_keyed(int compatible, char *vendor,
char *model, char *strflags,
blist_flags_t flags,
enum scsi_devinfo_key key);
extern int scsi_dev_info_list_del_keyed(char *vendor, char *model,
enum scsi_devinfo_key key);
extern int scsi_dev_info_add_list(enum scsi_devinfo_key key, const char *name);
extern int scsi_dev_info_remove_list(enum scsi_devinfo_key key);
extern int __init scsi_init_devinfo(void);
extern void scsi_exit_devinfo(void);
/* scsi_error.c */
extern void scmd_eh_abort_handler(struct work_struct *work);
extern enum blk_eh_timer_return scsi_timeout(struct request *req);
extern int scsi_error_handler(void *host);
extern enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *cmd);
extern void scsi_eh_wakeup(struct Scsi_Host *shost, unsigned int busy);
extern void scsi_eh_scmd_add(struct scsi_cmnd *);
void scsi_eh_ready_devs(struct Scsi_Host *shost,
struct list_head *work_q,
struct list_head *done_q);
int scsi_eh_get_sense(struct list_head *work_q,
struct list_head *done_q);
bool scsi_noretry_cmd(struct scsi_cmnd *scmd);
void scsi_eh_done(struct scsi_cmnd *scmd);
/* scsi_lib.c */
extern void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd);
extern void scsi_queue_insert(struct scsi_cmnd *cmd, int reason);
extern void scsi_io_completion(struct scsi_cmnd *, unsigned int);
extern void scsi_run_host_queues(struct Scsi_Host *shost);
extern void scsi_requeue_run_queue(struct work_struct *work);
extern void scsi_start_queue(struct scsi_device *sdev);
extern int scsi_mq_setup_tags(struct Scsi_Host *shost);
extern void scsi_mq_free_tags(struct kref *kref);
extern void scsi_exit_queue(void);
extern void scsi_evt_thread(struct work_struct *work);
/* scsi_proc.c */
#ifdef CONFIG_SCSI_PROC_FS
extern int scsi_proc_hostdir_add(const struct scsi_host_template *);
extern void scsi_proc_hostdir_rm(const struct scsi_host_template *);
extern void scsi_proc_host_add(struct Scsi_Host *);
extern void scsi_proc_host_rm(struct Scsi_Host *);
extern int scsi_init_procfs(void);
extern void scsi_exit_procfs(void);
#else
# define scsi_proc_hostdir_add(sht) 0
# define scsi_proc_hostdir_rm(sht) do { } while (0)
# define scsi_proc_host_add(shost) do { } while (0)
# define scsi_proc_host_rm(shost) do { } while (0)
# define scsi_init_procfs() (0)
# define scsi_exit_procfs() do { } while (0)
#endif /* CONFIG_PROC_FS */
/* scsi_scan.c */
void scsi_enable_async_suspend(struct device *dev);
extern int scsi_complete_async_scans(void);
extern int scsi_scan_host_selected(struct Scsi_Host *, unsigned int,
unsigned int, u64, enum scsi_scan_mode);
extern void scsi_forget_host(struct Scsi_Host *);
/* scsi_sysctl.c */
#ifdef CONFIG_SYSCTL
extern int scsi_init_sysctl(void);
extern void scsi_exit_sysctl(void);
#else
# define scsi_init_sysctl() (0)
# define scsi_exit_sysctl() do { } while (0)
#endif /* CONFIG_SYSCTL */
/* scsi_sysfs.c */
extern int scsi_sysfs_add_sdev(struct scsi_device *);
extern int scsi_sysfs_add_host(struct Scsi_Host *);
extern int scsi_sysfs_register(void);
extern void scsi_sysfs_unregister(void);
extern void scsi_sysfs_device_initialize(struct scsi_device *);
extern struct scsi_transport_template blank_transport_template;
extern void __scsi_remove_device(struct scsi_device *);
extern struct bus_type scsi_bus_type;
extern const struct attribute_group *scsi_shost_groups[];
/* scsi_netlink.c */
#ifdef CONFIG_SCSI_NETLINK
extern void scsi_netlink_init(void);
extern void scsi_netlink_exit(void);
extern struct sock *scsi_nl_sock;
#else
static inline void scsi_netlink_init(void) {}
static inline void scsi_netlink_exit(void) {}
#endif
/* scsi_pm.c */
#ifdef CONFIG_PM
extern const struct dev_pm_ops scsi_bus_pm_ops;
extern void scsi_autopm_get_target(struct scsi_target *);
extern void scsi_autopm_put_target(struct scsi_target *);
extern int scsi_autopm_get_host(struct Scsi_Host *);
extern void scsi_autopm_put_host(struct Scsi_Host *);
#else
static inline void scsi_autopm_get_target(struct scsi_target *t) {}
static inline void scsi_autopm_put_target(struct scsi_target *t) {}
static inline int scsi_autopm_get_host(struct Scsi_Host *h) { return 0; }
static inline void scsi_autopm_put_host(struct Scsi_Host *h) {}
#endif /* CONFIG_PM */
/* scsi_dh.c */
#ifdef CONFIG_SCSI_DH
void scsi_dh_add_device(struct scsi_device *sdev);
void scsi_dh_release_device(struct scsi_device *sdev);
#else
static inline void scsi_dh_add_device(struct scsi_device *sdev) { }
static inline void scsi_dh_release_device(struct scsi_device *sdev) { }
#endif
struct bsg_device *scsi_bsg_register_queue(struct scsi_device *sdev);
extern int scsi_device_max_queue_depth(struct scsi_device *sdev);
/*
* internal scsi timeout functions: for use by mid-layer and transport
* classes.
*/
#define SCSI_DEVICE_BLOCK_MAX_TIMEOUT 600 /* units in seconds */
#endif /* _SCSI_PRIV_H */
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