Good point; INQUIRY, REPORT LUNS, REQUEST SENSE, and NOTIFY DATA TRANSFER DEVICE do not report unit attention conditions. The comment should be changed, since that's not the reason for any retries here: > + /* > + * We can get a UNIT ATTENTION, for example a power on/reset, so > + * retry a few times (like sd.c does for TEST UNIT READY). > + * Experience shows some combinations of adapter/devices get at > + * least two power on/resets. > + * > + * Illegal requests (for devices that do not support REPORT LUNS) > + * should come through as a check condition, and will not generate > + * a retry. > + */ > -----Original Message----- > From: Jeremy Linton [mailto:jlinton@xxxxxxxxxxxxx] > Sent: Thursday, 07 March, 2013 10:07 AM > To: Elliott, Robert (Server Storage) > Cc: Rob Evers; linux-scsi@xxxxxxxxxxxxxxx; michaelc@xxxxxxxxxxx; > bvanassche@xxxxxxx; emilne@xxxxxxxxxx > Subject: Re: [PATCH V3 1/4] Encapsulate scsi_do_report_luns > > On 3/7/2013 9:47 AM, Elliott, Robert (Server Storage) wrote: > > >> +int scsi_do_report_luns(struct scsi_device *sdev, int length, + * We > >> can get a UNIT ATTENTION, for example a power on/reset, so + * > retry a > >> few times (like sd.c does for TEST UNIT READY). + * Experience shows > >> some combinations of adapter/devices get at + * least two power > >> on/resets. + for (retries = 0; retries < 3; retries++) { + > >> SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO "scsi scan: Sending" + > " > >> REPORT LUNS to %s (try %d)\n", devname, + > retries)); + result = > >> scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE, + > lun_data, > >> length, &sshdr, + SCSI_TIMEOUT + 4 * > HZ, 3, NULL); > > > > There's no guarantee that you'll get no more than two unit attention > > conditions at any particular time; > > Actually, if your getting any unit attentions from a report luns the > device > is broken. SAM5 5.14 > > "if a REPORT LUNS command enters the enabled command state, the device > server > shall process the REPORTS LUNS command and shall not report any unit > attention > conditions" > > This is not new behavior either. > > > There are a couple other places that say similar things, INQUIRY and REPORT > LUNS get special status for UA. Which is how you can scan a target/lun > configuration without interfering with its operation. Personally, I think the > TUR in the mid layer is incorrect as the TUR functionality needs to be hoisted > higher up the stack and the mid layer needs to use inquiry to validate device > communications. (got a patch for that too, but no point in posting it, as it > will be ignored). > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
