Date: Mon, 25 Nov 2002 12:10:14 -0800 (PST)
From: Nate Lawson <nate@root.org>
To: Yar Tikhiy <yar@freebsd.org>
Cc: freebsd-scsi@freebsd.org
Subject: Re: {da,sa,...}open bug?
Message-ID: <Pine.BSF.4.21.0211251208350.83036-100000@root.org>
In-Reply-To: <20021125134302.D14452@comp.chem.msu.su>
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On Mon, 25 Nov 2002, Yar Tikhiy wrote:
> On Fri, Nov 22, 2002 at 11:14:47AM -0800, Nate Lawson wrote:
> > On Fri, 22 Nov 2002, Yar Tikhiy wrote:
> > > The XXopen() methods of the da, sa etc drivers get a reference to
> > > the peripheral ("periph") through cam_periph_acquire() and don't
> > > release it on error exit. I suspect this leads to CAM wedge if the
> > > device is removed when its driver is in XXopen(). That is because
> > > the "periph" stays acquired (refcount > 0), but the XXopen() caller
> > > wouldn't invoke XXclose() subsequently since it sees XXopen() having
> > > failed. Thus CAM won't ever "forget" the device removed.
> > >
> > > Moreover, after I had patched daopen() to release the peripheral
> > > if returning non-zero error code, the CAM wedge has gone.
> >
> > Your approach sounds correct to me. open should call cam_periph_release
> > if it errors out after cam_periph_acquire. Care to submit a patch?
>
> Certainly! The patch is at the end of this message. I can commit
> it if it looks right to you.
Thanks. I have emailed a patch to re@ and will commit it upon approval.
> While preparing the fix, I noticed an additional couple of oddities.
> First, files under sys/cam/scsi are inconsistent as to the order of
> calling cam_periph_release() and cam_periph_unlock(): Some of them
> will call cam_periph_release() first, and the others will call it second.
> Then, there's a number of places in the code where cam_periph_unlock()
> won't be called before return on a cam_periph_acquire() error, though
> the "periph" has been locked.
I think this should be fixed. Please submit a patch for this.
-Nate
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