linux-kernel - Re: [PATCH 01/12] nvmem: imx-iim: use stack for nvmem

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Date:   Fri, 20 Oct 2017 16:47:59 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/12] nvmem: imx-iim: use stack for nvmem_config instead
 of malloc'ing it

On Fri, Oct 20, 2017 at 11:26:16PM +0900, Masahiro Yamada wrote:
> 2017-10-20 22:54 GMT+09:00 Greg KH <gregkh@...uxfoundation.org>:
> > On Fri, Oct 20, 2017 at 10:47:16PM +0900, Masahiro Yamada wrote:
> >> Hi Greg,
> >>
> >> 2017-10-20 22:32 GMT+09:00 Greg KH <gregkh@...uxfoundation.org>:
> >> > On Mon, Oct 09, 2017 at 03:26:30PM +0200, srinivas.kandagatla@...aro.org wrote:
> >> >> From: Masahiro Yamada <yamada.masahiro@...ionext.com>
> >> >>
> >> >> nvmem_register() copies all the members of nvmem_config to
> >> >> nvmem_device.  So, nvmem_config is one-time use data during
> >> >> probing.  There is no point to keep it until the driver detach.
> >> >> Using stack should be no problem because nvmem_config is pretty
> >> >> small.
> >> >>
> >> >> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> >> >> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> >> >> ---
> >> >>  drivers/nvmem/imx-iim.c | 27 ++++++++++++---------------
> >> >>  1 file changed, 12 insertions(+), 15 deletions(-)
> >> >>
> >> >> diff --git a/drivers/nvmem/imx-iim.c b/drivers/nvmem/imx-iim.c
> >> >> index 52ff65e0673f..a5992602709a 100644
> >> >> --- a/drivers/nvmem/imx-iim.c
> >> >> +++ b/drivers/nvmem/imx-iim.c
> >> >> @@ -34,7 +34,6 @@ struct imx_iim_drvdata {
> >> >>  struct iim_priv {
> >> >>       void __iomem *base;
> >> >>       struct clk *clk;
> >> >> -     struct nvmem_config nvmem;
> >> >>  };
> >> >>
> >> >>  static int imx_iim_read(void *context, unsigned int offset,
> >> >> @@ -108,7 +107,7 @@ static int imx_iim_probe(struct platform_device *pdev)
> >> >>       struct resource *res;
> >> >>       struct iim_priv *iim;
> >> >>       struct nvmem_device *nvmem;
> >> >> -     struct nvmem_config *cfg;
> >> >> +     struct nvmem_config cfg = {};
> >> >
> >> > You do realize you are now not zeroing out this structure, and have to
> >> > explicitly initialize all of the fields, right?
> >>
> >> Why?
> >>
> >> I am surely zeroing out the structure.
> >>
> >> Did you miss "= {};" in my code?
> >
> > Are you sure that does zero it out?  I know we have had issues with this
> > in the past...
> 
> Do you have a reference for that?
> 
> All members that are not specified in the initializer
> are set to 0 (or NULL).
> 
> "git show c7836d1593b87cb813c58cf64e08b052ebbe2a78"
> and do you agree that this is correct?

Ugh, you are right, that's what I get for reviewing 250+ patches at a
time, my fault, sorry for the noise.

Can you resend these?

thanks,

greg k-h