LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Roger Pau Monné" <roger.pau@citrix.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
	"Juergen Gross" <jgross@suse.com>, "Jens Axboe" <axboe@kernel.dk>,
	"open list" <linux-kernel@vger.kernel.org>,
	stable@vger.kernel.org,
	"open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
	xen-devel@lists.xenproject.org,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH 6/6] xen-blkfront: prepare request locally, only then put it on the shared ring
Date: Tue, 1 May 2018 10:15:26 +0100	[thread overview]
Message-ID: <20180501091526.6b6j6h6rh62646fx@MacBook-Pro-de-Roger.local> (raw)
In-Reply-To: <20180501082231.dzdbcghtwvlbkoys@MacBook-Pro-de-Roger.local>

On Tue, May 01, 2018 at 09:22:31AM +0100, Roger Pau Monné wrote:
> On Mon, Apr 30, 2018 at 11:01:50PM +0200, Marek Marczykowski-Górecki wrote:
> >  					    struct request *req,
> > -					    struct blkif_request **ring_req)
> > +					    struct blkif_request *ring_req)
> >  {
> >  	unsigned long id;
> >  
> > -	*ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
> > -	rinfo->ring.req_prod_pvt++;
> > -
> >  	id = get_id_from_freelist(rinfo);
> >  	rinfo->shadow[id].request = req;
> >  	rinfo->shadow[id].status = REQ_WAITING;
> >  	rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
> >  
> > -	(*ring_req)->u.rw.id = id;
> > +	ring_req->u.rw.id = id;
> >  
> >  	return id;
> >  }
> > @@ -545,23 +542,28 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
> >  static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
> >  {
> >  	struct blkfront_info *info = rinfo->dev_info;
> > -	struct blkif_request *ring_req;
> > +	struct blkif_request ring_req = { 0 };
> >  	unsigned long id;
> >  
> >  	/* Fill out a communications ring structure. */
> >  	id = blkif_ring_get_request(rinfo, req, &ring_req);
> 
> Maybe I'm missing something obvious here, but you are adding a struct
> allocated on the stack to the shadow ring copy, isn't this dangerous?

The above comment is wrong, you are storing a pointer to 'req' in the
shadow ring copy, which is fine and is not the ring request.

Roger.

      reply	other threads:[~2018-05-01  9:15 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 21:01 [PATCH 0/6] Fix XSA-155-like bugs in frontend drivers Marek Marczykowski-Górecki
2018-04-30 21:01 ` [PATCH 1/6] xen: Add RING_COPY_RESPONSE() Marek Marczykowski-Górecki
2018-04-30 21:25   ` Boris Ostrovsky
2018-04-30 21:27     ` Marek Marczykowski-Górecki
2018-04-30 21:41       ` Boris Ostrovsky
2018-04-30 21:01 ` [PATCH 2/6] xen-netfront: copy response out of shared buffer before accessing it Marek Marczykowski-Górecki
2018-05-02  5:20   ` [Xen-devel] " Oleksandr Andrushchenko
2018-04-30 21:01 ` [PATCH 3/6] xen-netfront: do not use data already exposed to backend Marek Marczykowski-Górecki
2018-04-30 21:01 ` [PATCH 4/6] xen-netfront: add range check for Tx response id Marek Marczykowski-Górecki
2018-05-01 10:05   ` [Xen-devel] " Wei Liu
2018-04-30 21:01 ` [PATCH 5/6] xen-blkfront: make local copy of response before using it Marek Marczykowski-Górecki
2018-04-30 21:01 ` [PATCH 6/6] xen-blkfront: prepare request locally, only then put it on the shared ring Marek Marczykowski-Górecki
2018-05-01  8:22   ` Roger Pau Monné
2018-05-01  9:15     ` Roger Pau Monné [this message]

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=20180501091526.6b6j6h6rh62646fx@MacBook-Pro-de-Roger.local \
    --to=roger.pau@citrix.com \
    --cc=axboe@kernel.dk \
    --cc=boris.ostrovsky@oracle.com \
    --cc=jgross@suse.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marmarek@invisiblethingslab.com \
    --cc=stable@vger.kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    --subject='Re: [Xen-devel] [PATCH 6/6] xen-blkfront: prepare request locally, only then put it on the shared ring' \
    /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).