[2-1-1] Overview
[2-1-2] Flow of scmds through EH
[2-1-3] Flow of control
- [2-2] EH through hostt->eh_strategy_handler()
- [2-2-1] Pre hostt->eh_strategy_handler() SCSI midlayer conditions
- [2-2-2] Post hostt->eh_strategy_handler() SCSI midlayer conditions
+ [2-2] EH through transportt->eh_strategy_handler()
+ [2-2-1] Pre transportt->eh_strategy_handler() SCSI midlayer conditions
+ [2-2-2] Post transportt->eh_strategy_handler() SCSI midlayer conditions
[2-2-3] Things to consider
The timeout handler is scsi_times_out(). When a timeout occurs, this
function
- 1. invokes optional hostt->eh_timedout() callback. Return value can
+ 1. invokes optional hostt->eh_timed_out() callback. Return value can
be one of
- EH_HANDLED
- This indicates that eh_timedout() dealt with the timeout. The
+ This indicates that eh_timed_out() dealt with the timeout. The
scmd is passed to __scsi_done() and thus linked into per-cpu
scsi_done_q. Normal command completion described in [1-2-1]
follows.
command will time out again.
- EH_NOT_HANDLED
- This is the same as when eh_timedout() callback doesn't exist.
+ This is the same as when eh_timed_out() callback doesn't exist.
Step #2 is taken.
2. scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD) is invoked for the
Note that this does not mean lower layers are quiescent. If a LLDD
completed a scmd with error status, the LLDD and lower layers are
assumed to forget about the scmd at that point. However, if a scmd
-has timed out, unless hostt->eh_timedout() made lower layers forget
+has timed out, unless hostt->eh_timed_out() made lower layers forget
about the scmd, which currently no LLDD does, the command is still
active as long as lower layers are concerned and completion could
occur at any time. Of course, all such completions are ignored as the
- Fine-grained EH callbacks
LLDD can implement fine-grained EH callbacks and let SCSI
midlayer drive error handling and call appropriate callbacks.
- This will be dicussed further in [2-1].
+ This will be discussed further in [2-1].
- eh_strategy_handler() callback
This is one big callback which should perform whole error
again.
To achieve these goals, EH performs recovery actions with increasing
-severity. Some actions are performed by issueing SCSI commands and
+severity. Some actions are performed by issuing SCSI commands and
others are performed by invoking one of the following fine-grained
hostt EH callbacks. Callbacks may be omitted and omitted ones are
considered to fail always.
layer of failure of the scmds.
-[2-2] EH through hostt->eh_strategy_handler()
+[2-2] EH through transportt->eh_strategy_handler()
- hostt->eh_strategy_handler() is invoked in the place of
+ transportt->eh_strategy_handler() is invoked in the place of
scsi_unjam_host() and it is responsible for whole recovery process.
On completion, the handler should have made lower layers forget about
all failed scmds and either ready for new commands or offline. Also,
except for #1 must be implemented by eh_strategy_handler().
-[2-2-1] Pre hostt->eh_strategy_handler() SCSI midlayer conditions
+[2-2-1] Pre transportt->eh_strategy_handler() SCSI midlayer conditions
The following conditions are true on entry to the handler.
- shost->host_failed == shost->host_busy
-[2-2-2] Post hostt->eh_strategy_handler() SCSI midlayer conditions
+[2-2-2] Post transportt->eh_strategy_handler() SCSI midlayer conditions
The following conditions must be true on exit from the handler.