LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [GIT PULL] two more s390 bug fixes for 4.17
Date: Thu, 31 May 2018 09:14:00 -0700	[thread overview]
Message-ID: <20180531161400.GB10203@infradead.org> (raw)
In-Reply-To: <20180530111140.40c791bd@mschwideX1>

On Wed, May 30, 2018 at 11:11:40AM +0200, Martin Schwidefsky wrote:
> On Wed, 30 May 2018 00:41:30 -0700
> Christoph Hellwig <hch@infradead.org> wrote:
> 
> > > -	req->completion_data = cqr;
> > > +	*((struct dasd_ccw_req **) blk_mq_rq_to_pdu(req)) = cqr;
> > > +  
> > 
> > Please don't play such tricks.  In general your driver structure
> > should have struct request embedded.  If for some reason
> > struct dasd_ccw_req has a different life time please create a new
> > structure instead of these hacks.
> 
> Why do you consider this to be a 'trick'? The blk_mq_rq_to_pdu is
> meant to be used to access a block of data that is is associated
> with a request, no? With the change we store a single value, the
> pointer to a struct dasd_ccw_req. The struct request comes first,
> later do_dasd_request creates the struct dasd_ccw_req with the
> CCW chain for the request. And for the blk timeout handler we need
> a way to find the dasd_ccw_req again.

We'll we try really hard to have a structure that we can use
container_of on.  At least a minimal container with just the pointer
for a quick fix, but in general it seems like you should be able
to allocate the whole dasd_ccw_req with the request and just initialize
it later.

  reply	other threads:[~2018-05-31 16:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-30  5:59 Martin Schwidefsky
2018-05-30  7:41 ` Christoph Hellwig
2018-05-30  9:11   ` Martin Schwidefsky
2018-05-31 16:14     ` Christoph Hellwig [this message]
2018-06-04  8:20       ` Martin Schwidefsky
2018-05-30 12:59   ` Sebastian Ott
2018-06-08 17:40     ` Sebastian Ott

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=20180531161400.GB10203@infradead.org \
    --to=hch@infradead.org \
    --cc=heiko.carstens@de.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=schwidefsky@de.ibm.com \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: [GIT PULL] two more s390 bug fixes for 4.17' \
    /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

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).