Messages in this thread | | | Date | Mon, 16 Nov 2015 10:31:33 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH v2] libata: add support for NCQ commands for SG interface |
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On Mon, Nov 16, 2015 at 08:47:19AM -0500, Mark Lord wrote: > On 15-10-27 01:49 AM, vinayak.kale@gmail.com wrote: > >From: Vinayak Kale <vinayak.kale@seagate.com> > > > >This patch is needed to make NCQ commands with FPDMA protocol value > >(eg READ/WRITE FPDMA) work over SCSI Generic (SG) interface. > .. > >+ /* For NCQ commands with FPDMA protocol, copy the tag value */ > >+ if (tf->protocol == ATA_PROT_NCQ) > >+ tf->nsect = qc->tag << 3; > >+ > > > What prevents the qc-tag value here from conflicting with in-flight I/O > using the exact same qc-tag ??
The SG command doesn't set the tag, it's being set from an allocated qc which can't otherwise be in-flight.
Thanks.
-- tejun
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