redundant slave_alloc() slave_destroy() calls

Attached is a scsi_debug driver view of a module load when 2 scsi devices are simulated in lk 2.5.50. The scsi_debug trace is slightly enhanced to show calls to slave_alloc(). Also the address of the passed scsi_device pointer is placed in brackets at the end of most lines.

There are even more slave_alloc() slave_destroy() pairs than I expected. The first pair looks very strange (i.e. no INQUIRY is issued). The slave_ alloc [_configure] [_destroy] sequencing looks sound, but it seems as though the scsi_scan logic is a little over-zealous in exercising it.

Doug Gilbert

scsi3 : scsi_debug, Version: 1.65 (20021119), num_devs=2, dev_size_mb=8, opts=0x1
scsi_debug: slave_alloc <3 0 0 0> [db1dc400]
scsi_debug: slave_destroy <3 0 0 0> [db1dc400]
scsi_debug: slave_alloc <3 0 0 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: cmd 12 00 00 00 3a 00 [db1dc400]
scsi_debug: slave_alloc <3 0 0 0> [db1dc000]
Vendor: Linux Model: scsi_debug Rev: 0004
Type: Direct-Access ANSI SCSI revision: 03
scsi_debug: cmd 12 01 00 00 ff 00 [db1dc400]
scsi_debug: cmd 12 01 83 00 ff 00 [db1dc400]
scsi_debug: slave_destroy <3 0 0 0> [db1dc400]
scsi_debug: slave_alloc <3 0 0 0> [db1dc400]
scsi_debug: cmd a0 00 00 00 00 00 00 00 04 08 00 00 [db1dc400]
scsi_debug: slave_destroy <3 0 0 1> [db1dc400]
scsi_debug: slave_alloc <3 0 0 1> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: cmd 12 00 00 00 3a 00 [db1dc400]
scsi_debug: slave_alloc <3 0 0 1> [db1d6c00]
Vendor: Linux Model: scsi_debug Rev: 0004
Type: Direct-Access ANSI SCSI revision: 03
scsi_debug: cmd 12 01 00 00 ff 00 [db1dc400]
scsi_debug: cmd 12 01 83 00 ff 00 [db1dc400]
scsi_debug: slave_destroy <3 0 1 0> [db1dc400]
scsi_debug: slave_alloc <3 0 1 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: ... <3 0 1 0> non-zero result=0x10000
scsi_debug: slave_destroy <3 0 2 0> [db1dc400]
scsi_debug: slave_alloc <3 0 2 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: ... <3 0 2 0> non-zero result=0x10000
scsi_debug: slave_destroy <3 0 3 0> [db1dc400]
scsi_debug: slave_alloc <3 0 3 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: ... <3 0 3 0> non-zero result=0x10000
scsi_debug: slave_destroy <3 0 4 0> [db1dc400]
scsi_debug: slave_alloc <3 0 4 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: ... <3 0 4 0> non-zero result=0x10000
scsi_debug: slave_destroy <3 0 5 0> [db1dc400]
scsi_debug: slave_alloc <3 0 5 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: ... <3 0 5 0> non-zero result=0x10000
scsi_debug: slave_destroy <3 0 6 0> [db1dc400]
scsi_debug: slave_alloc <3 0 6 0> [db1dc400]
scsi_debug: cmd 12 00 00 00 24 00 [db1dc400]
scsi_debug: ... <3 0 6 0> non-zero result=0x10000
scsi_debug: slave_destroy <3 0 6 0> [db1dc400]
scsi_debug: slave_configure <3 0 0 0> [db1dc000]
scsi_debug: cmd 00 00 00 00 00 00 [db1dc000]
scsi_debug: cmd 1a 08 08 00 80 00 [db1dc000]
SCSI device sdb: drive cache: write back
scsi_debug: cmd 25 00 00 00 00 00 00 00 00 00 [db1dc000]
scsi_debug: ... <3 0 0 0> non-zero result=0x2
scsi_debug: cmd 25 00 00 00 00 00 00 00 00 00 [db1dc000]
SCSI device sdb: 16384 512-byte hdwr sectors (8 MB)
sdb:<6>scsi_debug: cmd 28 00 00 00 00 00 00 00 08 00 [db1dc000] unknown partition table
Attached scsi disk sdb at scsi3, channel 0, id 0, lun 0
scsi_debug: slave_configure <3 0 0 1> [db1d6c00]
scsi_debug: cmd 00 00 00 00 00 00 [db1d6c00]
scsi_debug: cmd 1a 08 08 00 80 00 [db1d6c00]
SCSI device sdc: drive cache: write back
scsi_debug: cmd 25 00 00 00 00 00 00 00 00 00 [db1d6c00]
scsi_debug: ... <3 0 0 1> non-zero result=0x2
scsi_debug: cmd 25 00 00 00 00 00 00 00 00 00 [db1d6c00]
SCSI device sdc: 16384 512-byte hdwr sectors (8 MB)
sdc:<6>scsi_debug: cmd 28 00 00 00 00 00 00 00 08 00 [db1d6c00] unknown partition table
Attached scsi disk sdc at scsi3, channel 0, id 0, lun 1
scsi_debug: ... built 1 host(s)