linux-kernel - Re: [PATCH v2] staging: dgnc: check if kzalloc fails in dgnc_tty

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Message-ID: <alpine.LNX.2.03.1504071613380.19037@localhost.localdomain>
Date:	Tue, 7 Apr 2015 16:25:09 +0300 (EEST)
From:	Giedrius Statkevičius 
	<giedrius.statkevicius@...il.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
cc:	Giedrius Statkevičius 
	<giedrius.statkevicius@...il.com>, lidza.louina@...il.com,
	markh@...pro.net, devel@...verdev.osuosl.org,
	gregkh@...uxfoundation.org, driverdev-devel@...uxdriverproject.org,
	linux-kernel@...r.kernel.org, sudipm.mukherjee@...il.com
Subject: Re: [PATCH v2] staging: dgnc: check if kzalloc fails in
 dgnc_tty_init()

On Tue, 7 Apr 2015, Dan Carpenter wrote:

> On Tue, Apr 07, 2015 at 03:40:17PM +0300, Giedrius Statkevičius wrote:
> > If one of the allocations of memory for storing a channel information struct
> > fails then free all the successful allocations and return -ENOMEM that gets
> > propogated to the pci layer.  Also, remove a bogus skipping in the next part of
> > the initiation if a previous memory allocation failed because we won't execute
> > that if any of the allocations failed.
> > 
> > Signed-off-by: Giedrius Statkevičius <giedrius.statkevicius@...il.com>
> > ---
> > v2: Only returning -ENOMEM if an allocation failed isn't enough as it was
> > spotted by Sudip so create a new label that frees all successfully allocated
> > stuff and only then returns -ENOMEM. Also, remove a unnecessary check in the
> > next loop.
> > 
> >  drivers/staging/dgnc/dgnc_tty.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/staging/dgnc/dgnc_tty.c b/drivers/staging/dgnc/dgnc_tty.c
> > index ce4187f..60d7e49 100644
> > --- a/drivers/staging/dgnc/dgnc_tty.c
> > +++ b/drivers/staging/dgnc/dgnc_tty.c
> > @@ -316,6 +316,8 @@ int dgnc_tty_init(struct dgnc_board *brd)
> >  			 * interrupt context, and there are no locks held.
> >  			 */
> >  			brd->channels[i] = kzalloc(sizeof(*brd->channels[i]), GFP_KERNEL);
> > +			if (!brd->channels[i])
> > +				goto err_free_channels;
> 
> The comments here say that sometimes brd->channels[] are allocated
> earlier.  If that's true then the error handling is not correct.  But
> I don't think it is true...  Could you investigate and delete the
> comments and unnecessary "if (!brd->channels[i])" NULL check.
> 
> regards,
> dan carpenter
> 

I've checked this earlier and now looked over again and I didn't find any other
place where this is allocated. My thought was that deleting that comment and
that check could be too much for one patch. I'll send a v3.

Su pagarba / Regards,
Giedrius