LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Leon Romanovsky <leon@kernel.org>
To: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: mustafa.ismail@intel.com, shiraz.saleem@intel.com,
	dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] RDMA/irdma: Improve the way 'cqp_request' structures are cleaned when they are recycled
Date: Wed, 21 Jul 2021 08:11:26 +0300	[thread overview]
Message-ID: <YPesftdeBpzJUhMZ@unreal> (raw)
In-Reply-To: <629bc34e-ef41-9af6-9ed7-71865251a62c@wanadoo.fr>

On Tue, Jul 20, 2021 at 03:05:55PM +0200, Christophe JAILLET wrote:
> Le 20/07/2021 à 14:23, Leon Romanovsky a écrit :
> > On Mon, Jul 19, 2021 at 07:02:15PM +0200, Christophe JAILLET wrote:
> > > A set of IRDMA_CQP_SW_SQSIZE_2048 (i.e. 2048) 'cqp_request' are
> > > pre-allocated and zeroed in 'irdma_create_cqp()' (hw.c).  These
> > > structures are managed with the 'cqp->cqp_avail_reqs' list which keeps
> > > track of available entries.
> > > 
> > > In 'irdma_free_cqp_request()' (utils.c), when an entry is recycled and goes
> > > back to the 'cqp_avail_reqs' list, some fields are reseted.
> > > 
> > > However, one of these fields, 'compl_info', is initialized within
> > > 'irdma_alloc_and_get_cqp_request()'.
> > > 
> > > Move the corresponding memset to 'irdma_free_cqp_request()' so that the
> > > clean-up is done in only one place. This makes the logic more easy to
> > > understand.
> > 
> > I'm not so sure. The function irdma_alloc_and_get_cqp_request() returns
> > prepared cqp_request and all users expect that it will returned cleaned
> > one. The reliance on some other place to clear part of the structure is
> > prone to errors.
> 
> Ok, so maybe, moving:
> 	cqp_request->request_done = false;
> 	cqp_request->callback_fcn = NULL;
> 	cqp_request->waiting = false;
> from 'irdma_free_cqp_request()' to 'irdma_alloc_and_get_cqp_request()' to
> make explicit what is reseted makes more sense?

I think so, but it requires double check that these cleared values are
not used after irdma_free_cqp_request().

This is another reason why clearing fields after _free_ routine is
mostly wrong. It hides errors when data is accessed after release.

Thanks

      reply	other threads:[~2021-07-21  5:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19 17:02 Christophe JAILLET
2021-07-20 12:23 ` Leon Romanovsky
2021-07-20 13:05   ` Christophe JAILLET
2021-07-21  5:11     ` Leon Romanovsky [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=YPesftdeBpzJUhMZ@unreal \
    --to=leon@kernel.org \
    --cc=christophe.jaillet@wanadoo.fr \
    --cc=dledford@redhat.com \
    --cc=jgg@ziepe.ca \
    --cc=kernel-janitors@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=mustafa.ismail@intel.com \
    --cc=shiraz.saleem@intel.com \
    --subject='Re: [PATCH] RDMA/irdma: Improve the way '\''cqp_request'\'' structures are cleaned when they are recycled' \
    /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).