From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: FCP target reset Date: Tue, 04 Aug 2009 10:38:28 -0400 Message-ID: <4A7847E4.8090304@interlog.com> References: <20090803162302.GA9872@schmichrtp.de.ibm.com> <4A774AC8.8080805@emulex.com> Reply-To: dgilbert@interlog.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.infotech.no ([82.134.31.41]:51858 "EHLO elrond.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755602AbZHDOie (ORCPT ); Tue, 4 Aug 2009 10:38:34 -0400 In-Reply-To: <4A774AC8.8080805@emulex.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Smart Cc: Christof Schmitt , "linux-scsi@vger.kernel.org" It looks like "target reset" is being phased out of SCSI terminology and being partially replaced by "hard reset". The third paragraph in the introduction of draft SAM-5 (sam5r02.pdf section 1.1) states: "The following concepts from previous versions of this standard are made obsolete by this standard: a) support for the SPI-5 SCSI transport protocol; b) Contingent Allegiance; c) the TARGET RESET task management function; d) basic task management model; e) untagged tasks; and f) linked command function." The TARGET RESET task management function last appeared in SAM-2 (ANSI INCITS 366-2003). A "hard reset" is associated with a power cycle at an initiator, target or somewhere in between. There is no SCSI task management function to generate a hard reset. Some transports have the ability to generate hard resets via non-SCSI protocols. For example in SAS a target can be reset with a SMP PHY CONTROL request to an expander phy attached to a phy on that target. SAS also has a lower order "link reset" which is invisible at the SCSI protocol level. So is there a "hard reset" hook somewhere in FCP-3 ? Doug Gilbert James Smart wrote: > Just because a newer rev of the spec doesn't do something does not mean > that all the targets/environments stopped using it... Target Reset was > a mandatory item for FCP-2 compliance, which is what most of the stuff > in the field is at. So, I recommend that the header be updated with > the older definition - It can be flagged any way you desire (/* > Deprecated as of FCP-3 */). > > As for use in LLD's - there's nothing else (TMF-wise) that works at the > I_T nexus level to map to the shost eh_target_reset_handler. Thus, I'd > continue to use it for the entrypoint. You can always choose to not > implement the entry point, but my recommendation is to support it if > possible. It's much better than having to resort to a "bus" or "adapter" > reset after a lun reset fails. > > -- james s > > Christof Schmitt wrote: >> While trying to replace the Fibre Channel protocol definitions in >> zfcp with the definitions in include/scsi/fc i came across the FCP >> target reset flag. >> >>> From what i understand, older versions of the FCP standard defined the >> target reset flag, but newer versions do not. Adhering to the newer >> standard, the file include/scsi/fc/fc_fcp.h does not define the target >> reset. >> >> Does this mean that FC device drivers should not issue target resets >> any more? >> >> Some FC device drivers in Linux define the flag: >> >> grep -r FCP_TARGET_RESET * >> drivers/s390/scsi/zfcp_dbf.h: zfcp_scsi_dbf_event(flag == >> FCP_TARGET_RESET ? "trst" : "lrst", tag, 1, >> drivers/s390/scsi/zfcp_def.h:#define FCP_TARGET_RESET 0x20 >> drivers/s390/scsi/zfcp_scsi.c: return >> zfcp_task_mgmt_function(scpnt, FCP_TARGET_RESET); >> drivers/scsi/lpfc/lpfc_scsi.c: FCP_TARGET_RESET); >> drivers/scsi/lpfc/lpfc_scsi.c: FCP_TARGET_RESET); >> drivers/scsi/lpfc/lpfc_scsi.h:#define FCP_TARGET_RESET 0x20 /* >> bit 5 */ >> >> If the target reset is not required, i would remove it from zfcp. If >> it is still required, would adding it to include/scsi/fc/fc_fcp.h make >> sense, probably flagged as "obsolete"? >> >> -- >> Christof Schmitt >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >