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Re: [dm-devel] rdac.c patch not quite right.



On Wed December 08, 2010 3:27 AM, Christophe Varoqui Wrote:
> On lun., 2010-11-29 at 19:03 -0500, Chaskiel Grundman wrote:
> > commit 362d2e5f215894818b52a0d03b723b75917390fb
> > added the following block to rdac.c:
> >
> >         } else if ((inq.PQ_PDT & 0x20) || (inq.PQ_PDT & 0x7f)) {
> >                 /* LUN not connected*/
> >                 ret = PATH_DOWN;
> >                 goto done;
> >         }
> >
> > I don't know what the intended effect actually was, but since
> > (inq.PQ_PDT & 0x20) will be true if (inq.PQ_PDT & 0x7f), the code is
> > incorrect as-is. I have some dell RDAC devices, but I cannot delete
> > targets on any of them to test this.
> >
> > Update, after reading some scsi docs: If RDAC is using the standard
> > peripheral qualifier semantics, I think the following is what should be
> > used instead
> >
> >
> >         } else if ((inq.PQ_PDT & 0xE0) == 0x20 || inq.PQ_PDT == 0x7f) {
> >
> > This form checks for the PQ bits being 001 or 011, and if 011, also
> > that the device type has the standard value for an unsupported
> > lun.
> >
> > Alternatively,
> >
> >         } else if ((inq.PQ_PDT & 0xC0) == 0x20) {
> >
> > does not validate the device type bits in case the PQ is 011
> >
> As the original author of the aforementioned change, do you ack this
> patch ?

Chaskiel,

Thanks for your findings and inputs.

Christophe,

Please include this fix in rdac path checker.

Thanks,
Vijay

---

In case of not connected device, only first condition is checked for PQ in rdac path checker. This patch
corrects the check by masking MSB 3 bits and comparing it with 0x20. 

Signed-off-by: Vijay Chauhan <vijay chauhan lsi com>
---
--- multipath-tools-orig/libmultipath/checkers/rdac.c	2010-12-06 02:59:40.000000000 -0600
+++ multipath-tools/libmultipath/checkers/rdac.c	2010-12-06 04:01:37.000000000 -0600
@@ -107,7 +107,7 @@ libcheck_check (struct checker * c)
 	if (0 != do_inq(c->fd, 0xC9, &inq, sizeof(struct volume_access_inq))) {
 		ret = PATH_DOWN;
 		goto done;
-	} else if ((inq.PQ_PDT & 0x20) || (inq.PQ_PDT & 0x7f)) {
+	} else if (((inq.PQ_PDT & 0xE0) == 0x20) || (inq.PQ_PDT & 0x7f)) {
 		/* LUN not connected*/
 		ret = PATH_DOWN;
 		goto done;
--





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