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  1. 13 Oct, 2008 2 commits
    • Mike Christie's avatar
      [SCSI] qla4xxx: return SCSI_MLQUEUE_TARGET_BUSY when driver has detected session error · c5e98e91
      Mike Christie authored 
      When qla4xxx begins recovery and the iscsi class is firing up to handle
it, we need to retrn SCSI_MLQUEUE_TARGET_BUSY from the driver instead
of host busy, because the session recovery only affects the one target.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Acked-by: default avatarDavid C Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      c5e98e91
    • Mike Christie's avatar
      [SCSI] Add helper code so transport classes/driver can control queueing (v3) · f0c0a376
      Mike Christie authored 
      SCSI-ml manages the queueing limits for the device and host, but
does not do so at the target level. However something something similar
can come in userful when a driver is transitioning a transport object to
the the blocked state, becuase at that time we do not want to queue
io and we do not want the queuecommand to be called again.

The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers.
You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit
a transport level queueing issue like the hw cannot allocate some
resource at the iscsi session/connection level, or the target has temporarily
closed or shrunk the queueing window, or if we are transitioning
to the blocked state.

bnx2i, when they rework their firmware according to netdev
developers requests, will also need to be able to limit queueing at this
level. bnx2i will hook into libiscsi, but will allocate a scsi host per
netdevice/hba, so unlike pure software iscsi/iser which is allocating
a host per session, it cannot set the scsi_host->can_queue and return
SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport.

The iscsi class/driver can also set a scsi_target->can_queue value which
reflects the max commands the driver/class can support. For iscsi this
reflects the number of commands we can support for each session due to
session/connection hw limits, driver limits, and to also reflect the
session/targets's queueing window.

Changes:
v1 - initial patch.
v2 - Fix scsi_run_queue handling of multiple blocked targets.
Previously we would break from the main loop if a device was added back on
the starved list. We now run over the list and check if any target is
blocked.
v3 - Rediff for scsi-misc.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      f0c0a376
  3. 12 Oct, 2008 38 commits
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