From: Dan Carpenter <dan.carpenter@oracle.com>
To: Ching Huang <ching2048@areca.com.tw>
Cc: martin.petersen@oracle.com,
James.Bottomley@HansenPartnership.com,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
hch@infradead.org, colin.king@canonical.com
Subject: Re: [PATCH 2/3] scsi: arcmsr: Fix suspend/resume of ACB_ADAPTER_TYPE_B part 2
Date: Tue, 22 Jan 2019 10:48:16 +0300 [thread overview]
Message-ID: <20190122074816.GC11828@kadam> (raw)
In-Reply-To: <1547718748.5079.34.camel@Centos6.3-64>
On Thu, Jan 17, 2019 at 05:52:28PM +0800, Ching Huang wrote:
> On Thu, 2019-01-17 at 12:16 +0300, Dan Carpenter wrote:
> > On Thu, Jan 17, 2019 at 04:47:07PM +0800, Ching Huang wrote:
> > > On Thu, 2019-01-17 at 10:59 +0300, Dan Carpenter wrote:
> > > > On Thu, Jan 17, 2019 at 11:45:03AM +0800, Ching Huang wrote:
> > > > > >From Ching Huang <ching2048@areca.com.tw>
> > > > >
> > > > > Fix suspend/resume of ACB_ADAPTER_TYPE_B part 2.
> > > > >
> > > >
> > > > What does this look like from a user perspective? Does it fail every
> > > > time or does it only fail sometimes?
> > > >
> > > > What's the bug exactly?
> > > >
> > > > There is no Fixes tag...
> > > >From user's perspective, hibernate/resume are OK.
> > > But following IO may cause 'isr get an illegal ccb command' in
> > > log/messages sometime.
> > > >
> >
> >
> > You will need to resend with that information included in the commit
> > message.
> OK. I will resend this patch later.
> >
> > > > > Signed-off-by: Ching Huang <ching2048@areca.com.tw>
> > > > > ---
> > > > >
> > > > > diff --git a/drivers/scsi/arcmsr/arcmsr.h b/drivers/scsi/arcmsr/arcmsr.h
> > > > > index a94c513..b98c632 100755
> > > > > --- a/drivers/scsi/arcmsr/arcmsr.h
> > > > > +++ b/drivers/scsi/arcmsr/arcmsr.h
> > > > > @@ -508,9 +508,9 @@ struct MessageUnit_A
> > > > > struct MessageUnit_B
> > > > > {
> > > > > uint32_t post_qbuffer[ARCMSR_MAX_HBB_POSTQUEUE];
> > > > > - uint32_t done_qbuffer[ARCMSR_MAX_HBB_POSTQUEUE];
> > > > > + volatile uint32_t done_qbuffer[ARCMSR_MAX_HBB_POSTQUEUE];
> > > >
> > > > There is a well known rule of thumb that when someone uses "volatile"
> > > > in the kernel it means there is a locking problem... Is this __iomem or
> > > > something?
> > > The done_qbuffer was a command completion queue, it was an area written
> > > by IO processor and read by device driver. So, ...
> >
> > I'm not totally positive I understand this sentence. I can find a bunch
> > of places which read from this buffer, but I haven't immediately found
> > which place writes to it. Can you give me a function name that I should
> > read?
> Well, we allocate memory for struct MessageUnit_B in
> arcmsr_alloc_ccb_pool(), by assign to acb->dma_coherent_handle2.
> Then we tell IO controller its DMA address in arcmsr_iop_confirm().
> When a command was completed, controller's firmware program will write a
> completion ccb in done_qbuffer through DMA. So, you can't see any driver
> funtion write to it.
DMA memory doesn't need to be marked as volatile.
regards,
dan carpenter
next prev parent reply other threads:[~2019-01-22 7:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-17 3:45 [PATCH 2/3] scsi: arcmsr: Fix suspend/resume of ACB_ADAPTER_TYPE_B part 2 Ching Huang
2019-01-17 7:59 ` Dan Carpenter
2019-01-17 8:47 ` Ching Huang
2019-01-17 9:16 ` Dan Carpenter
2019-01-17 9:52 ` Ching Huang
2019-01-22 7:48 ` Dan Carpenter [this message]
2019-01-22 0:03 ` Ching Huang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190122074816.GC11828@kadam \
--to=dan.carpenter@oracle.com \
--cc=James.Bottomley@HansenPartnership.com \
--cc=ching2048@areca.com.tw \
--cc=colin.king@canonical.com \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).