From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH] SAS: use sas_rphy instead of sas_end_device to obtain address. Date: Fri, 12 Aug 2016 07:54:03 -0700 Message-ID: <1471013643.2407.14.camel@linux.vnet.ibm.com> References: <1470902352-96734-1-git-send-email-jthumshirn@suse.de> <1470928175.2334.9.camel@linux.vnet.ibm.com> <20160811164350.vakulxlr4xlsyrxn@c203.arch.suse.de> <1470938407.2334.36.camel@linux.vnet.ibm.com> <20160812100854.4cks5qxsommfwsjk@c203.arch.suse.de> <20160812131125.n7p47dcf7sinwg54@c203.arch.suse.de> <1471012475.2407.6.camel@linux.vnet.ibm.com> <75620aea-33df-9cf3-7eb2-ec209384eb4e@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <75620aea-33df-9cf3-7eb2-ec209384eb4e@suse.de> Sender: stable-owner@vger.kernel.org To: Hannes Reinecke , Johannes Thumshirn Cc: "Martin K . Petersen" , Linux SCSI Mailinglist , Linux Kernel Mailinglist , stable@vger.kernel.org, #@suse.de, v4.5+@suse.de List-Id: linux-scsi@vger.kernel.org On Fri, 2016-08-12 at 16:39 +0200, Hannes Reinecke wrote: > On 08/12/2016 04:34 PM, James Bottomley wrote: > > On Fri, 2016-08-12 at 15:11 +0200, Johannes Thumshirn wrote: > > > On Fri, Aug 12, 2016 at 12:08:54PM +0200, Johannes Thumshirn > > > wrote: > > > > Ok, we can't use the rphy because of wide-ports. We can't fix > > > > it to an end device either, as this makes some peoples systems > > > > unbootable. Now let's find a third option satisfying the needs > > > > of SAS wide-ports and my customers (and others running 4.5+ > > > > with a SAS enclosure). > > > > > > > > I'm digging... > > > > > > > > > To answer myself, Hannes suggested doing it like this: > > > > > > diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c > > > index 53ef1cb6..1d82053 100644 > > > --- a/drivers/scsi/ses.c > > > +++ b/drivers/scsi/ses.c > > > @@ -587,7 +587,7 @@ static void ses_match_to_enclosure(struct > > > enclosure_device *edev, > > > > > > ses_enclosure_data_process(edev, to_scsi_device(edev > > > ->edev.parent), 0); > > > > > > - if (is_sas_attached(sdev)) > > > + if (scsi_is_sas_rphy(&sdev->sdev_gendev)) > > > efd.addr = sas_get_address(sdev); > > > > > > if (efd.addr) { > > > > > > > > > The reasoning behind this is, we only read the address if we have > > > an actual sas_rphy. > > > > > > Would this be OK for you? > > > > Could you please debug the why? first before we start throwing > > patches around. is_sas_attached(sdev) returns true if the sdev is > > the child of a SAS controller. What is this thing you've found > > that has a sdev attached to a SAS controller but isn't and end > > device? > > > > if is_sas_attached() passes but scsi_is_sas_rphy() doesn't you've > > got a device that is the child of a SAS host which has an rphy but > > which isn't an expander or end device. That's pretty much the end > > of the list of things which can lie at the end of rphys since we > > lump the SATA possibilities in with end devices. > > > hpsa magic. > > The hpsa driver has some sdevs handled by the SAS transport class > (for the pass-through devices) and some sdevs (eg logical volumes) > which are not. As 'is_sas_attached' only checks if the _host_ has the > SAS transport class attached (which it will have), it will not work > as expected for devices which are not handled by the SAS transport > class (like the 'normal' hpsa logical volumes). And the logical > volumes don't even has a SAS address assigned to them, so in either > case the original check will draw a blank here. Thanks! I've found it in hpsa_add_device() for logical vs physical setups and, indeed, the way they call scsi_add_device will ensure that we don't attach the SAS transport class because the rphy isn't properly initialised so the last check (rphy->identify.device_type == SAS_END_DEVICE) won't pass .... in fact it's a bit of a mess. The change looks fine, since it's tighter than the original and, since this will be the last consumer of is_sas_attached(), you can remove that as well. James