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-rw-r--r--Documentation/scsi/scsi_eh.txt30
1 files changed, 12 insertions, 18 deletions
diff --git a/Documentation/scsi/scsi_eh.txt b/Documentation/scsi/scsi_eh.txt
index 37eca00796ee..11e447bdb3a5 100644
--- a/Documentation/scsi/scsi_eh.txt
+++ b/Documentation/scsi/scsi_eh.txt
@@ -70,7 +70,7 @@ with the command.
scmd is requeued to blk queue.
- otherwise
- scsi_eh_scmd_add(scmd, 0) is invoked for the command. See
+ scsi_eh_scmd_add(scmd) is invoked for the command. See
[1-3] for details of this function.
@@ -103,13 +103,14 @@ function
eh_timed_out() callback did not handle the command.
Step #2 is taken.
- 2. If the host supports asynchronous completion (as indicated by the
- no_async_abort setting in the host template) scsi_abort_command()
- is invoked to schedule an asynchrous abort. If that fails
- Step #3 is taken.
+ 2. scsi_abort_command() is invoked to schedule an asynchrous abort.
+ Asynchronous abort are not invoked for commands which the
+ SCSI_EH_ABORT_SCHEDULED flag is set (this indicates that the command
+ already had been aborted once, and this is a retry which failed),
+ or when the EH deadline is expired. In these case Step #3 is taken.
- 2. scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD) is invoked for the
- command. See [1-3] for more information.
+ 3. scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD) is invoked for the
+ command. See [1-4] for more information.
[1-3] Asynchronous command aborts
@@ -124,16 +125,13 @@ function
scmds enter EH via scsi_eh_scmd_add(), which does the following.
- 1. Turns on scmd->eh_eflags as requested. It's 0 for error
- completions and SCSI_EH_CANCEL_CMD for timeouts.
+ 1. Links scmd->eh_entry to shost->eh_cmd_q
- 2. Links scmd->eh_entry to shost->eh_cmd_q
+ 2. Sets SHOST_RECOVERY bit in shost->shost_state
- 3. Sets SHOST_RECOVERY bit in shost->shost_state
+ 3. Increments shost->host_failed
- 4. Increments shost->host_failed
-
- 5. Wakes up SCSI EH thread if shost->host_busy == shost->host_failed
+ 4. Wakes up SCSI EH thread if shost->host_busy == shost->host_failed
As can be seen above, once any scmd is added to shost->eh_cmd_q,
SHOST_RECOVERY shost_state bit is turned on. This prevents any new
@@ -249,7 +247,6 @@ scmd->allowed.
1. Error completion / time out
ACTION: scsi_eh_scmd_add() is invoked for scmd
- - set scmd->eh_eflags
- add scmd to shost->eh_cmd_q
- set SHOST_RECOVERY
- shost->host_failed++
@@ -263,7 +260,6 @@ scmd->allowed.
3. scmd recovered
ACTION: scsi_eh_finish_cmd() is invoked to EH-finish scmd
- - clear scmd->eh_eflags
- scsi_setup_cmd_retry()
- move from local eh_work_q to local eh_done_q
LOCKING: none
@@ -456,8 +452,6 @@ except for #1 must be implemented by eh_strategy_handler().
- shost->host_failed is zero.
- - Each scmd's eh_eflags field is cleared.
-
- Each scmd is in such a state that scsi_setup_cmd_retry() on the
scmd doesn't make any difference.