Don't reset ->total_link_count on nested calls of vfs_path_lookup()

[people/ms/linux.git] / include / scsi / scsi_host.h

#ifndef _SCSI_SCSI_HOST_H
#define _SCSI_SCSI_HOST_H

#include <linux/device.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include <linux/blk-mq.h>
#include <scsi/scsi.h>

struct request_queue;
struct block_device;
struct completion;
struct module;
struct scsi_cmnd;
struct scsi_device;
struct scsi_host_cmd_pool;
struct scsi_target;
struct Scsi_Host;
struct scsi_host_cmd_pool;
struct scsi_transport_template;
struct blk_queue_tags;


/*
 * The various choices mean:
 * NONE: Self evident.  Host adapter is not capable of scatter-gather.
 * ALL:  Means that the host adapter module can do scatter-gather,
 *       and that there is no limit to the size of the table to which
 *       we scatter/gather data.  The value we set here is the maximum
 *       single element sglist.  To use chained sglists, the adapter
 *       has to set a value beyond ALL (and correctly use the chain
 *       handling API.
 * Anything else:  Indicates the maximum number of chains that can be
 *       used in one scatter-gather request.
 */
#define SG_NONE 0
#define SG_ALL  SCSI_MAX_SG_SEGMENTS

#define MODE_UNKNOWN 0x00
#define MODE_INITIATOR 0x01
#define MODE_TARGET 0x02

#define DISABLE_CLUSTERING 0
#define ENABLE_CLUSTERING 1

struct scsi_host_template {
        struct module *module;
        const char *name;

        /*
         * Used to initialize old-style drivers.  For new-style drivers
         * just perform all work in your module initialization function.
         *
         * Status:  OBSOLETE
         */
        int (* detect)(struct scsi_host_template *);

        /*
         * Used as unload callback for hosts with old-style drivers.
         *
         * Status: OBSOLETE
         */
        int (* release)(struct Scsi_Host *);

        /*
         * The info function will return whatever useful information the
         * developer sees fit.  If not provided, then the name field will
         * be used instead.
         *
         * Status: OPTIONAL
         */
        const char *(* info)(struct Scsi_Host *);

        /*
         * Ioctl interface
         *
         * Status: OPTIONAL
         */
        int (* ioctl)(struct scsi_device *dev, int cmd, void __user *arg);


#ifdef CONFIG_COMPAT
        /* 
         * Compat handler. Handle 32bit ABI.
         * When unknown ioctl is passed return -ENOIOCTLCMD.
         *
         * Status: OPTIONAL
         */
        int (* compat_ioctl)(struct scsi_device *dev, int cmd, void __user *arg);
#endif

        /*
         * The queuecommand function is used to queue up a scsi
         * command block to the LLDD.  When the driver finished
         * processing the command the done callback is invoked.
         *
         * If queuecommand returns 0, then the HBA has accepted the
         * command.  The done() function must be called on the command
         * when the driver has finished with it. (you may call done on the
         * command before queuecommand returns, but in this case you
         * *must* return 0 from queuecommand).
         *
         * Queuecommand may also reject the command, in which case it may
         * not touch the command and must not call done() for it.
         *
         * There are two possible rejection returns:
         *
         *   SCSI_MLQUEUE_DEVICE_BUSY: Block this device temporarily, but
         *   allow commands to other devices serviced by this host.
         *
         *   SCSI_MLQUEUE_HOST_BUSY: Block all devices served by this
         *   host temporarily.
         *
         * For compatibility, any other non-zero return is treated the
         * same as SCSI_MLQUEUE_HOST_BUSY.
         *
         * NOTE: "temporarily" means either until the next command for#
         * this device/host completes, or a period of time determined by
         * I/O pressure in the system if there are no other outstanding
         * commands.
         *
         * STATUS: REQUIRED
         */
        int (* queuecommand)(struct Scsi_Host *, struct scsi_cmnd *);

        /*
         * This is an error handling strategy routine.  You don't need to
         * define one of these if you don't want to - there is a default
         * routine that is present that should work in most cases.  For those
         * driver authors that have the inclination and ability to write their
         * own strategy routine, this is where it is specified.  Note - the
         * strategy routine is *ALWAYS* run in the context of the kernel eh
         * thread.  Thus you are guaranteed to *NOT* be in an interrupt
         * handler when you execute this, and you are also guaranteed to
         * *NOT* have any other commands being queued while you are in the
         * strategy routine. When you return from this function, operations
         * return to normal.
         *
         * See scsi_error.c scsi_unjam_host for additional comments about
         * what this function should and should not be attempting to do.
         *
         * Status: REQUIRED     (at least one of them)
         */
        int (* eh_abort_handler)(struct scsi_cmnd *);
        int (* eh_device_reset_handler)(struct scsi_cmnd *);
        int (* eh_target_reset_handler)(struct scsi_cmnd *);
        int (* eh_bus_reset_handler)(struct scsi_cmnd *);
        int (* eh_host_reset_handler)(struct scsi_cmnd *);

        /*
         * Before the mid layer attempts to scan for a new device where none
         * currently exists, it will call this entry in your driver.  Should
         * your driver need to allocate any structs or perform any other init
         * items in order to send commands to a currently unused target/lun
         * combo, then this is where you can perform those allocations.  This
         * is specifically so that drivers won't have to perform any kind of
         * "is this a new device" checks in their queuecommand routine,
         * thereby making the hot path a bit quicker.
         *
         * Return values: 0 on success, non-0 on failure
         *
         * Deallocation:  If we didn't find any devices at this ID, you will
         * get an immediate call to slave_destroy().  If we find something
         * here then you will get a call to slave_configure(), then the
         * device will be used for however long it is kept around, then when
         * the device is removed from the system (or * possibly at reboot
         * time), you will then get a call to slave_destroy().  This is
         * assuming you implement slave_configure and slave_destroy.
         * However, if you allocate memory and hang it off the device struct,
         * then you must implement the slave_destroy() routine at a minimum
         * in order to avoid leaking memory
         * each time a device is tore down.
         *
         * Status: OPTIONAL
         */
        int (* slave_alloc)(struct scsi_device *);

        /*
         * Once the device has responded to an INQUIRY and we know the
         * device is online, we call into the low level driver with the
         * struct scsi_device *.  If the low level device driver implements
         * this function, it *must* perform the task of setting the queue
         * depth on the device.  All other tasks are optional and depend
         * on what the driver supports and various implementation details.
         * 
         * Things currently recommended to be handled at this time include:
         *
         * 1.  Setting the device queue depth.  Proper setting of this is
         *     described in the comments for scsi_change_queue_depth.
         * 2.  Determining if the device supports the various synchronous
         *     negotiation protocols.  The device struct will already have
         *     responded to INQUIRY and the results of the standard items
         *     will have been shoved into the various device flag bits, eg.
         *     device->sdtr will be true if the device supports SDTR messages.
         * 3.  Allocating command structs that the device will need.
         * 4.  Setting the default timeout on this device (if needed).
         * 5.  Anything else the low level driver might want to do on a device
         *     specific setup basis...
         * 6.  Return 0 on success, non-0 on error.  The device will be marked
         *     as offline on error so that no access will occur.  If you return
         *     non-0, your slave_destroy routine will never get called for this
         *     device, so don't leave any loose memory hanging around, clean
         *     up after yourself before returning non-0
         *
         * Status: OPTIONAL
         */
        int (* slave_configure)(struct scsi_device *);

        /*
         * Immediately prior to deallocating the device and after all activity
         * has ceased the mid layer calls this point so that the low level
         * driver may completely detach itself from the scsi device and vice
         * versa.  The low level driver is responsible for freeing any memory
         * it allocated in the slave_alloc or slave_configure calls. 
         *
         * Status: OPTIONAL
         */
        void (* slave_destroy)(struct scsi_device *);

        /*
         * Before the mid layer attempts to scan for a new device attached
         * to a target where no target currently exists, it will call this
         * entry in your driver.  Should your driver need to allocate any
         * structs or perform any other init items in order to send commands
         * to a currently unused target, then this is where you can perform
         * those allocations.
         *
         * Return values: 0 on success, non-0 on failure
         *
         * Status: OPTIONAL
         */
        int (* target_alloc)(struct scsi_target *);

        /*
         * Immediately prior to deallocating the target structure, and
         * after all activity to attached scsi devices has ceased, the
         * midlayer calls this point so that the driver may deallocate
         * and terminate any references to the target.
         *
         * Status: OPTIONAL
         */
        void (* target_destroy)(struct scsi_target *);

        /*
         * If a host has the ability to discover targets on its own instead
         * of scanning the entire bus, it can fill in this function and
         * call scsi_scan_host().  This function will be called periodically
         * until it returns 1 with the scsi_host and the elapsed time of
         * the scan in jiffies.
         *
         * Status: OPTIONAL
         */
        int (* scan_finished)(struct Scsi_Host *, unsigned long);

        /*
         * If the host wants to be called before the scan starts, but
         * after the midlayer has set up ready for the scan, it can fill
         * in this function.
         *
         * Status: OPTIONAL
         */
        void (* scan_start)(struct Scsi_Host *);

        /*
         * Fill in this function to allow the queue depth of this host
         * to be changeable (on a per device basis).  Returns either
         * the current queue depth setting (may be different from what
         * was passed in) or an error.  An error should only be
         * returned if the requested depth is legal but the driver was
         * unable to set it.  If the requested depth is illegal, the
         * driver should set and return the closest legal queue depth.
         *
         * Status: OPTIONAL
         */
        int (* change_queue_depth)(struct scsi_device *, int);

        /*
         * This function determines the BIOS parameters for a given
         * harddisk.  These tend to be numbers that are made up by
         * the host adapter.  Parameters:
         * size, device, list (heads, sectors, cylinders)
         *
         * Status: OPTIONAL
         */
        int (* bios_param)(struct scsi_device *, struct block_device *,
                        sector_t, int []);

        /*
         * This function is called when one or more partitions on the
         * device reach beyond the end of the device.
         *
         * Status: OPTIONAL
         */
        void (*unlock_native_capacity)(struct scsi_device *);

        /*
         * Can be used to export driver statistics and other infos to the
         * world outside the kernel ie. userspace and it also provides an
         * interface to feed the driver with information.
         *
         * Status: OBSOLETE
         */
        int (*show_info)(struct seq_file *, struct Scsi_Host *);
        int (*write_info)(struct Scsi_Host *, char *, int);

        /*
         * This is an optional routine that allows the transport to become
         * involved when a scsi io timer fires. The return value tells the
         * timer routine how to finish the io timeout handling:
         * EH_HANDLED:          I fixed the error, please complete the command
         * EH_RESET_TIMER:      I need more time, reset the timer and
         *                      begin counting again
         * EH_NOT_HANDLED       Begin normal error recovery
         *
         * Status: OPTIONAL
         */
        enum blk_eh_timer_return (*eh_timed_out)(struct scsi_cmnd *);

        /* This is an optional routine that allows transport to initiate
         * LLD adapter or firmware reset using sysfs attribute.
         *
         * Return values: 0 on success, -ve value on failure.
         *
         * Status: OPTIONAL
         */

        int (*host_reset)(struct Scsi_Host *shost, int reset_type);
#define SCSI_ADAPTER_RESET      1
#define SCSI_FIRMWARE_RESET     2


        /*
         * Name of proc directory
         */
        const char *proc_name;

        /*
         * Used to store the procfs directory if a driver implements the
         * show_info method.
         */
        struct proc_dir_entry *proc_dir;

        /*
         * This determines if we will use a non-interrupt driven
         * or an interrupt driven scheme.  It is set to the maximum number
         * of simultaneous commands a given host adapter will accept.
         */
        int can_queue;

        /*
         * In many instances, especially where disconnect / reconnect are
         * supported, our host also has an ID on the SCSI bus.  If this is
         * the case, then it must be reserved.  Please set this_id to -1 if
         * your setup is in single initiator mode, and the host lacks an
         * ID.
         */
        int this_id;

        /*
         * This determines the degree to which the host adapter is capable
         * of scatter-gather.
         */
        unsigned short sg_tablesize;
        unsigned short sg_prot_tablesize;

        /*
         * Set this if the host adapter has limitations beside segment count.
         */
        unsigned int max_sectors;

        /*
         * DMA scatter gather segment boundary limit. A segment crossing this
         * boundary will be split in two.
         */
        unsigned long dma_boundary;

        /*
         * This specifies "machine infinity" for host templates which don't
         * limit the transfer size.  Note this limit represents an absolute
         * maximum, and may be over the transfer limits allowed for
         * individual devices (e.g. 256 for SCSI-1).
         */
#define SCSI_DEFAULT_MAX_SECTORS        1024

        /*
         * True if this host adapter can make good use of linked commands.
         * This will allow more than one command to be queued to a given
         * unit on a given host.  Set this to the maximum number of command
         * blocks to be provided for each device.  Set this to 1 for one
         * command block per lun, 2 for two, etc.  Do not set this to 0.
         * You should make sure that the host adapter will do the right thing
         * before you try setting this above 1.
         */
        short cmd_per_lun;

        /*
         * present contains counter indicating how many boards of this
         * type were found when we did the scan.
         */
        unsigned char present;

        /* If use block layer to manage tags, this is tag allocation policy */
        int tag_alloc_policy;

        /*
         * Track QUEUE_FULL events and reduce queue depth on demand.
         */
        unsigned track_queue_depth:1;

        /*
         * This specifies the mode that a LLD supports.
         */
        unsigned supported_mode:2;

        /*
         * True if this host adapter uses unchecked DMA onto an ISA bus.
         */
        unsigned unchecked_isa_dma:1;

        /*
         * True if this host adapter can make good use of clustering.
         * I originally thought that if the tablesize was large that it
         * was a waste of CPU cycles to prepare a cluster list, but
         * it works out that the Buslogic is faster if you use a smaller
         * number of segments (i.e. use clustering).  I guess it is
         * inefficient.
         */
        unsigned use_clustering:1;

        /*
         * True for emulated SCSI host adapters (e.g. ATAPI).
         */
        unsigned emulated:1;

        /*
         * True if the low-level driver performs its own reset-settle delays.
         */
        unsigned skip_settle_delay:1;

        /* True if the controller does not support WRITE SAME */
        unsigned no_write_same:1;

        /*
         * True if asynchronous aborts are not supported
         */
        unsigned no_async_abort:1;

        /*
         * Countdown for host blocking with no commands outstanding.
         */
        unsigned int max_host_blocked;

        /*
         * Default value for the blocking.  If the queue is empty,
         * host_blocked counts down in the request_fn until it restarts
         * host operations as zero is reached.  
         *
         * FIXME: This should probably be a value in the template
         */
#define SCSI_DEFAULT_HOST_BLOCKED       7

        /*
         * Pointer to the sysfs class properties for this host, NULL terminated.
         */
        struct device_attribute **shost_attrs;

        /*
         * Pointer to the SCSI device properties for this host, NULL terminated.
         */
        struct device_attribute **sdev_attrs;

        /*
         * List of hosts per template.
         *
         * This is only for use by scsi_module.c for legacy templates.
         * For these access to it is synchronized implicitly by
         * module_init/module_exit.
         */
        struct list_head legacy_hosts;

        /*
         * Vendor Identifier associated with the host
         *
         * Note: When specifying vendor_id, be sure to read the
         *   Vendor Type and ID formatting requirements specified in
         *   scsi_netlink.h
         */
        u64 vendor_id;

        /*
         * Additional per-command data allocated for the driver.
         */
        unsigned int cmd_size;
        struct scsi_host_cmd_pool *cmd_pool;

        /* temporary flag to disable blk-mq I/O path */
        bool disable_blk_mq;
};

/*
 * Temporary #define for host lock push down. Can be removed when all
 * drivers have been updated to take advantage of unlocked
 * queuecommand.
 *
 */
#define DEF_SCSI_QCMD(func_name) \
        int func_name(struct Scsi_Host *shost, struct scsi_cmnd *cmd)   \
        {                                                               \
                unsigned long irq_flags;                                \
                int rc;                                                 \
                spin_lock_irqsave(shost->host_lock, irq_flags);         \
                scsi_cmd_get_serial(shost, cmd);                        \
                rc = func_name##_lck (cmd, cmd->scsi_done);                     \
                spin_unlock_irqrestore(shost->host_lock, irq_flags);    \
                return rc;                                              \
        }


/*
 * shost state: If you alter this, you also need to alter scsi_sysfs.c
 * (for the ascii descriptions) and the state model enforcer:
 * scsi_host_set_state()
 */
enum scsi_host_state {
        SHOST_CREATED = 1,
        SHOST_RUNNING,
        SHOST_CANCEL,
        SHOST_DEL,
        SHOST_RECOVERY,
        SHOST_CANCEL_RECOVERY,
        SHOST_DEL_RECOVERY,
};

struct Scsi_Host {
        /*
         * __devices is protected by the host_lock, but you should
         * usually use scsi_device_lookup / shost_for_each_device
         * to access it and don't care about locking yourself.
         * In the rare case of being in irq context you can use
         * their __ prefixed variants with the lock held. NEVER
         * access this list directly from a driver.
         */
        struct list_head        __devices;
        struct list_head        __targets;
        
        struct scsi_host_cmd_pool *cmd_pool;
        spinlock_t              free_list_lock;
        struct list_head        free_list; /* backup store of cmd structs */
        struct list_head        starved_list;

        spinlock_t              default_lock;
        spinlock_t              *host_lock;

        struct mutex            scan_mutex;/* serialize scanning activity */

        struct list_head        eh_cmd_q;
        struct task_struct    * ehandler;  /* Error recovery thread. */
        struct completion     * eh_action; /* Wait for specific actions on the
                                              host. */
        wait_queue_head_t       host_wait;
        struct scsi_host_template *hostt;
        struct scsi_transport_template *transportt;

        /*
         * Area to keep a shared tag map (if needed, will be
         * NULL if not).
         */
        union {
                struct blk_queue_tag    *bqt;
                struct blk_mq_tag_set   tag_set;
        };

        atomic_t host_busy;                /* commands actually active on low-level */
        atomic_t host_blocked;

        unsigned int host_failed;          /* commands that failed.
                                              protected by host_lock */
        unsigned int host_eh_scheduled;    /* EH scheduled without command */
    
        unsigned int host_no;  /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */

        /* next two fields are used to bound the time spent in error handling */
        int eh_deadline;
        unsigned long last_reset;


        /*
         * These three parameters can be used to allow for wide scsi,
         * and for host adapters that support multiple busses
         * The last two should be set to 1 more than the actual max id
         * or lun (e.g. 8 for SCSI parallel systems).
         */
        unsigned int max_channel;
        unsigned int max_id;
        u64 max_lun;

        /*
         * This is a unique identifier that must be assigned so that we
         * have some way of identifying each detected host adapter properly
         * and uniquely.  For hosts that do not support more than one card
         * in the system at one time, this does not need to be set.  It is
         * initialized to 0 in scsi_register.
         */
        unsigned int unique_id;

        /*
         * The maximum length of SCSI commands that this host can accept.
         * Probably 12 for most host adapters, but could be 16 for others.
         * or 260 if the driver supports variable length cdbs.
         * For drivers that don't set this field, a value of 12 is
         * assumed.
         */
        unsigned short max_cmd_len;

        int this_id;
        int can_queue;
        short cmd_per_lun;
        short unsigned int sg_tablesize;
        short unsigned int sg_prot_tablesize;
        unsigned int max_sectors;
        unsigned long dma_boundary;
        /*
         * In scsi-mq mode, the number of hardware queues supported by the LLD.
         *
         * Note: it is assumed that each hardware queue has a queue depth of
         * can_queue. In other words, the total queue depth per host
         * is nr_hw_queues * can_queue.
         */
        unsigned nr_hw_queues;
        /* 
         * Used to assign serial numbers to the cmds.
         * Protected by the host lock.
         */
        unsigned long cmd_serial_number;
        
        unsigned active_mode:2;
        unsigned unchecked_isa_dma:1;
        unsigned use_clustering:1;

        /*
         * Host has requested that no further requests come through for the
         * time being.
         */
        unsigned host_self_blocked:1;
    
        /*
         * Host uses correct SCSI ordering not PC ordering. The bit is
         * set for the minority of drivers whose authors actually read
         * the spec ;).
         */
        unsigned reverse_ordering:1;

        /* Task mgmt function in progress */
        unsigned tmf_in_progress:1;

        /* Asynchronous scan in progress */
        unsigned async_scan:1;

        /* Don't resume host in EH */
        unsigned eh_noresume:1;

        /* The controller does not support WRITE SAME */
        unsigned no_write_same:1;

        unsigned use_blk_mq:1;
        unsigned use_cmd_list:1;

        /*
         * Optional work queue to be utilized by the transport
         */
        char work_q_name[20];
        struct workqueue_struct *work_q;

        /*
         * Task management function work queue
         */
        struct workqueue_struct *tmf_work_q;

        /* The transport requires the LUN bits NOT to be stored in CDB[1] */
        unsigned no_scsi2_lun_in_cdb:1;

        /*
         * Value host_blocked counts down from
         */
        unsigned int max_host_blocked;

        /* Protection Information */
        unsigned int prot_capabilities;
        unsigned char prot_guard_type;

        /*
         * q used for scsi_tgt msgs, async events or any other requests that
         * need to be processed in userspace
         */
        struct request_queue *uspace_req_q;

        /* legacy crap */
        unsigned long base;
        unsigned long io_port;
        unsigned char n_io_port;
        unsigned char dma_channel;
        unsigned int  irq;
        

        enum scsi_host_state shost_state;

        /* ldm bits */
        struct device           shost_gendev, shost_dev;

        /*
         * List of hosts per template.
         *
         * This is only for use by scsi_module.c for legacy templates.
         * For these access to it is synchronized implicitly by
         * module_init/module_exit.
         */
        struct list_head sht_legacy_list;

        /*
         * Points to the transport data (if any) which is allocated
         * separately
         */
        void *shost_data;

        /*
         * Points to the physical bus device we'd use to do DMA
         * Needed just in case we have virtual hosts.
         */
        struct device *dma_dev;

        /*
         * We should ensure that this is aligned, both for better performance
         * and also because some compilers (m68k) don't automatically force
         * alignment to a long boundary.
         */
        unsigned long hostdata[0]  /* Used for storage of host specific stuff */
                __attribute__ ((aligned (sizeof(unsigned long))));
};

#define         class_to_shost(d)       \
        container_of(d, struct Scsi_Host, shost_dev)

#define shost_printk(prefix, shost, fmt, a...)  \
        dev_printk(prefix, &(shost)->shost_gendev, fmt, ##a)

static inline void *shost_priv(struct Scsi_Host *shost)
{
        return (void *)shost->hostdata;
}

int scsi_is_host_device(const struct device *);

static inline struct Scsi_Host *dev_to_shost(struct device *dev)
{
        while (!scsi_is_host_device(dev)) {
                if (!dev->parent)
                        return NULL;
                dev = dev->parent;
        }
        return container_of(dev, struct Scsi_Host, shost_gendev);
}

static inline int scsi_host_in_recovery(struct Scsi_Host *shost)
{
        return shost->shost_state == SHOST_RECOVERY ||
                shost->shost_state == SHOST_CANCEL_RECOVERY ||
                shost->shost_state == SHOST_DEL_RECOVERY ||
                shost->tmf_in_progress;
}

extern bool scsi_use_blk_mq;

static inline bool shost_use_blk_mq(struct Scsi_Host *shost)
{
        return shost->use_blk_mq;
}

extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *);
extern void scsi_flush_work(struct Scsi_Host *);

extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int);
extern int __must_check scsi_add_host_with_dma(struct Scsi_Host *,
                                               struct device *,
                                               struct device *);
extern void scsi_scan_host(struct Scsi_Host *);
extern void scsi_rescan_device(struct device *);
extern void scsi_remove_host(struct Scsi_Host *);
extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
extern void scsi_host_put(struct Scsi_Host *t);
extern struct Scsi_Host *scsi_host_lookup(unsigned short);
extern const char *scsi_host_state_name(enum scsi_host_state);
extern void scsi_cmd_get_serial(struct Scsi_Host *, struct scsi_cmnd *);

static inline int __must_check scsi_add_host(struct Scsi_Host *host,
                                             struct device *dev)
{
        return scsi_add_host_with_dma(host, dev, dev);
}

static inline struct device *scsi_get_device(struct Scsi_Host *shost)
{
        return shost->shost_gendev.parent;
}

/**
 * scsi_host_scan_allowed - Is scanning of this host allowed
 * @shost:      Pointer to Scsi_Host.
 **/
static inline int scsi_host_scan_allowed(struct Scsi_Host *shost)
{
        return shost->shost_state == SHOST_RUNNING ||
               shost->shost_state == SHOST_RECOVERY;
}

extern void scsi_unblock_requests(struct Scsi_Host *);
extern void scsi_block_requests(struct Scsi_Host *);

struct class_container;

extern struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
                                                void (*) (struct request_queue *));
/*
 * These two functions are used to allocate and free a pseudo device
 * which will connect to the host adapter itself rather than any
 * physical device.  You must deallocate when you are done with the
 * thing.  This physical pseudo-device isn't real and won't be available
 * from any high-level drivers.
 */
extern void scsi_free_host_dev(struct scsi_device *);
extern struct scsi_device *scsi_get_host_dev(struct Scsi_Host *);

/*
 * DIF defines the exchange of protection information between
 * initiator and SBC block device.
 *
 * DIX defines the exchange of protection information between OS and
 * initiator.
 */
enum scsi_host_prot_capabilities {
        SHOST_DIF_TYPE1_PROTECTION = 1 << 0, /* T10 DIF Type 1 */
        SHOST_DIF_TYPE2_PROTECTION = 1 << 1, /* T10 DIF Type 2 */
        SHOST_DIF_TYPE3_PROTECTION = 1 << 2, /* T10 DIF Type 3 */

        SHOST_DIX_TYPE0_PROTECTION = 1 << 3, /* DIX between OS and HBA only */
        SHOST_DIX_TYPE1_PROTECTION = 1 << 4, /* DIX with DIF Type 1 */
        SHOST_DIX_TYPE2_PROTECTION = 1 << 5, /* DIX with DIF Type 2 */
        SHOST_DIX_TYPE3_PROTECTION = 1 << 6, /* DIX with DIF Type 3 */
};

/*
 * SCSI hosts which support the Data Integrity Extensions must
 * indicate their capabilities by setting the prot_capabilities using
 * this call.
 */
static inline void scsi_host_set_prot(struct Scsi_Host *shost, unsigned int mask)
{
        shost->prot_capabilities = mask;
}

static inline unsigned int scsi_host_get_prot(struct Scsi_Host *shost)
{
        return shost->prot_capabilities;
}

static inline int scsi_host_prot_dma(struct Scsi_Host *shost)
{
        return shost->prot_capabilities >= SHOST_DIX_TYPE0_PROTECTION;
}

static inline unsigned int scsi_host_dif_capable(struct Scsi_Host *shost, unsigned int target_type)
{
        static unsigned char cap[] = { 0,
                                       SHOST_DIF_TYPE1_PROTECTION,
                                       SHOST_DIF_TYPE2_PROTECTION,
                                       SHOST_DIF_TYPE3_PROTECTION };

        if (target_type >= ARRAY_SIZE(cap))
                return 0;

        return shost->prot_capabilities & cap[target_type] ? target_type : 0;
}

static inline unsigned int scsi_host_dix_capable(struct Scsi_Host *shost, unsigned int target_type)
{
#if defined(CONFIG_BLK_DEV_INTEGRITY)
        static unsigned char cap[] = { SHOST_DIX_TYPE0_PROTECTION,
                                       SHOST_DIX_TYPE1_PROTECTION,
                                       SHOST_DIX_TYPE2_PROTECTION,
                                       SHOST_DIX_TYPE3_PROTECTION };

        if (target_type >= ARRAY_SIZE(cap))
                return 0;

        return shost->prot_capabilities & cap[target_type];
#endif
        return 0;
}

/*
 * All DIX-capable initiators must support the T10-mandated CRC
 * checksum.  Controllers can optionally implement the IP checksum
 * scheme which has much lower impact on system performance.  Note
 * that the main rationale for the checksum is to match integrity
 * metadata with data.  Detecting bit errors are a job for ECC memory
 * and buses.
 */

enum scsi_host_guard_type {
        SHOST_DIX_GUARD_CRC = 1 << 0,
        SHOST_DIX_GUARD_IP  = 1 << 1,
};

static inline void scsi_host_set_guard(struct Scsi_Host *shost, unsigned char type)
{
        shost->prot_guard_type = type;
}

static inline unsigned char scsi_host_get_guard(struct Scsi_Host *shost)
{
        return shost->prot_guard_type;
}

/* legacy interfaces */
extern struct Scsi_Host *scsi_register(struct scsi_host_template *, int);
extern void scsi_unregister(struct Scsi_Host *);
extern int scsi_host_set_state(struct Scsi_Host *, enum scsi_host_state);

#endif /* _SCSI_SCSI_HOST_H */