On Tue, Dec 04, 2018 at 11:16:59AM +0000, Peter Rosin wrote:
> Hi!
>
> This patch looks like a good idea. However, a nitpick below.
>
> On 2018-12-01 11:01, Nicholas Mc Guire wrote:
> > devm_kstrdup() may return NULL if internal allocation failed.
> > Thus using name, value is unsafe without being checked. As
> > i2c_demux_pinctrl_probe() can return -ENOMEM in other cases
> > a dev_err() message is included to make the failure location
> > clear.
> >
> > Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
> > Fixes: e35478eac030 ("i2c: mux: demux-pinctrl: run properly with multiple instances")
> > ---
> >
> > Problem located with experimental coccinelle script
> >
> > Q: The use of devm_kstrdup() seems a bit odd while technically not wrong,
> > personally I think devm_kasprintf() would be more suitable here.
> >
> > Patch was compile tested with: multi_v7_defconfig
> > (implies I2C_DEMUX_PINCTRL=y)
> >
> > Patch is against 4.20-rc4 (localversion-next is next-20181130)
> >
> > drivers/i2c/muxes/i2c-demux-pinctrl.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
> > index 035032e..c466999 100644
> > --- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
> > +++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
> > @@ -244,6 +244,12 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
> >
> > props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
> > props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
> > + if (!props[i].name || !props[i].value) {
> > + dev_err(&pdev->dev,
> > + "chan %d name, value allocation failed\n", i);
>
> Please drop this memory allocation failure message. You should get such a
> message from devm_kstrdup.
>
hm...tried to figure out where that message would be comming
from - but I could not find any point in the call tree that
would issue such a message ?
devm_kstrdup()
-> devm_kmalloc()
-> alloc_dr()
--> kmalloc_track_caller() (non-NUMA)
| -> __kmalloc_node()
| -> __do_kmalloc_node()
`-> __kmalloc_node_track_caller() (NUMA)
-> __do_kmalloc_node()
__do_kmalloc_node() seems like it simply returns NULL but
issues no failure message.
Am I overlooking something ?
thx!
hofrat
> Cheers,
> Peter
>
> > + err = -ENOMEM;
> > + goto err_rollback;
> > + }
> > props[i].length = 3;
> >
> > of_changeset_init(&priv->chan[i].chgset);
> >
>
