diff options
Diffstat (limited to 'Documentation/scsi/scsi_eh.txt')
| -rw-r--r-- | Documentation/scsi/scsi_eh.txt | 30 |
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. |