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scsi: remove the old scsi_module.c initialization model
After more than 15 years all users of this legacy interface are finally gone. Rest in peace! Signed-off-by: Christoph Hellwig <[email protected]> Signed-off-by: Martin K. Petersen <[email protected]>
This commit is contained in:
Christoph Hellwig
Martin K. Petersen
parent
616434e2aa
commit
83c9f08e6c
5 changed files with 1 additions and 259 deletions
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@ -114,9 +114,7 @@ called "xxx" could be defined as
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"static int xxx_slave_alloc(struct scsi_device * sdev) { /* code */ }"
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** the scsi_host_alloc() function is a replacement for the rather vaguely
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named scsi_register() function in most situations. The scsi_register()
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and scsi_unregister() functions remain to support legacy LLDs that use
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the passive initialization model.
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named scsi_register() function in most situations.
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Hotplug initialization model
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@ -228,79 +226,6 @@ slave_configure() callbacks). Such instances are "owned" by the mid-level.
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struct scsi_device instances are freed after slave_destroy().
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Passive initialization model
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============================
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These older LLDs include a file called "scsi_module.c" [yes the ".c" is a
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little surprising] in their source code. For that file to work an
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instance of struct scsi_host_template with the name "driver_template"
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needs to be defined. Here is a typical code sequence used in this model:
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static struct scsi_host_template driver_template = {
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...
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};
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#include "scsi_module.c"
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The scsi_module.c file contains two functions:
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- init_this_scsi_driver() which is executed when the LLD is
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initialized (i.e. boot time or module load time)
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- exit_this_scsi_driver() which is executed when the LLD is shut
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down (i.e. module unload time)
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Note: since these functions are tagged with __init and __exit qualifiers
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an LLD should not call them explicitly (since the kernel does that).
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Here is an example of an initialization sequence when two hosts are
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detected (so detect() returns 2) and the SCSI bus scan on each host
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finds 1 SCSI device (and a second device does not respond).
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LLD mid level LLD
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===----------------------=========-----------------===------
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init_this_scsi_driver() ----+
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detect() -----------------+
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| |
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| scsi_register()
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| scsi_register()
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slave_alloc()
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slave_configure() --> scsi_change_queue_depth()
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slave_alloc() ***
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slave_destroy() ***
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slave_alloc()
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slave_configure()
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slave_alloc() ***
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slave_destroy() ***
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------------------------------------------------------------
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The mid level invokes scsi_change_queue_depth() with "cmd_per_lun" for that
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host as the queue length. These settings can be overridden by a
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slave_configure() supplied by the LLD.
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*** For scsi devices that the mid level tries to scan but do not
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respond, a slave_alloc(), slave_destroy() pair is called.
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Here is an LLD shutdown sequence:
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LLD mid level LLD
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===----------------------=========-----------------===------
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exit_this_scsi_driver() ----+
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slave_destroy()
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release() --> scsi_unregister()
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slave_destroy()
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release() --> scsi_unregister()
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------------------------------------------------------------
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An LLD need not define slave_destroy() (i.e. it is optional).
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The shortcoming of the "passive initialization model" is that host
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registration and de-registration are (typically) tied to LLD initialization
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and shutdown. Once the LLD is initialized then a new host that appears
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(e.g. via hotplugging) cannot easily be added without a redundant
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driver shutdown and re-initialization. It may be possible to write an LLD
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that uses both initialization models.
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Reference Counting
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==================
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The Scsi_Host structure has had reference counting infrastructure added.
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@ -738,7 +663,6 @@ The interface functions are listed below in alphabetical order.
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Summary:
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bios_param - fetch head, sector, cylinder info for a disk
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detect - detects HBAs this driver wants to control
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eh_timed_out - notify the host that a command timer expired
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eh_abort_handler - abort given command
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eh_bus_reset_handler - issue SCSI bus reset
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@ -748,7 +672,6 @@ Summary:
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ioctl - driver can respond to ioctls
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proc_info - supports /proc/scsi/{driver_name}/{host_no}
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queuecommand - queue scsi command, invoke 'done' on completion
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release - release all resources associated with given host
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slave_alloc - prior to any commands being sent to a new device
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slave_configure - driver fine tuning for given device after attach
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slave_destroy - given device is about to be shut down
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@ -784,28 +707,6 @@ Details:
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sector_t capacity, int params[3])
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/**
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* detect - detects HBAs this driver wants to control
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* @shtp: host template for this driver.
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*
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* Returns number of hosts this driver wants to control. 0 means no
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* suitable hosts found.
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*
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* Locks: none held
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*
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* Calling context: process [invoked from init_this_scsi_driver()]
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*
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* Notes: First function called from the SCSI mid level on this
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* driver. Upper level drivers (e.g. sd) may not (yet) be present.
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* For each host found, this method should call scsi_register()
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* [see hosts.c].
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*
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* Defined in: LLD (required if "passive initialization mode" is used,
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* not invoked in "hotplug initialization mode")
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**/
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int detect(struct scsi_host_template * shtp)
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/**
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* eh_timed_out - The timer for the command has just fired
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* @scp: identifies command timing out
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@ -1073,27 +974,6 @@ Details:
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int queuecommand(struct Scsi_Host *shost, struct scsi_cmnd * scp)
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/**
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* release - release all resources associated with given host
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* @shp: host to be released.
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*
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* Return value ignored (could soon be a function returning void).
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*
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* Locks: none held
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*
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* Calling context: process
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*
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* Notes: Invoked from scsi_module.c's exit_this_scsi_driver().
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* LLD's implementation of this function should call
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* scsi_unregister(shp) prior to returning.
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* Only needed for old-style host templates.
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*
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* Defined in: LLD (required in "passive initialization model",
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* should not be defined in hotplug model)
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**/
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int release(struct Scsi_Host * shp)
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/**
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* slave_alloc - prior to any commands being sent to a new device
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* (i.e. just prior to scan) this call is made
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