scsi_debug driver puzzle

[Laurence Oberman]

Hello

I have what to me is a puzzle but is likely a stupid question about
the queuecommand interface in the scsi_debug driver.

I see the host template set for  scsi_debug_queuecommand but in the
driver we have the function declared as int
scsi_debug_queuecommand_lck
So how is this working.

Egrep pattern: scsi_debug_queuecommand

  File Line
0 scsi_debug.c 3551 int scsi_debug_queuecommand_lck(struct scsi_cmnd
*SCpnt, done_funct_t done)
1 scsi_debug.c 3900 static DEF_SCSI_QCMD(scsi_debug_queuecommand)
2 scsi_debug.c 3912 .queuecommand =  scsi_debug_queuecommand,

Thanks
Laurence
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Re: scsi_debug driver puzzle

[Bryn M. Reeves]

On 03/31/2014 06:32 PM, Laurence Oberman wrote:
   File Line
 0 scsi_debug.c 3551 int scsi_debug_queuecommand_lck(struct scsi_cmnd
 *SCpnt, done_funct_t done)
 1 scsi_debug.c 3900 static DEF_SCSI_QCMD(scsi_debug_queuecommand)
 2 scsi_debug.c 3912 .queuecommand =  scsi_debug_queuecommand,

Magical scsi_host.h macro as part of the effort to push host_lock down.
The macro creates a function named as its argument which takes and drops
the shost-host_lock around a call to the real queuecommand function:

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);

http://fpaste.org/90345/88875139/

Cheers,
Bryn.
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