Hi Geert,
Thank you for a very prompt response.
> Hi Lukasz,
>
> On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@xxxxxxx> wrote:
> > Call spi_slave_abort() only when the spidev->spi is !NULL and the
> > structure hasn't already been kfreed.
> >
> > Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> > Reported-by: Julia Lawall <julia.lawall@xxxxxxx>
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > Signed-off-by: Lukasz Majewski <lukma@xxxxxxx>
>
> Thanks for your patch!
>
> > --- a/drivers/spi/spidev.c
> > +++ b/drivers/spi/spidev.c
> > @@ -600,15 +600,16 @@ static int spidev_open(struct inode *inode,
> > struct file *filp) static int spidev_release(struct inode *inode,
> > struct file *filp) {
> > struct spidev_data *spidev;
> > + int dofree;
>
> bool?
It may be bool, yes - I took this "int" from the original code (further
down in the patch), as I've moved it a bit up.
>
> >
> > mutex_lock(&device_list_lock);
> > spidev = filp->private_data;
> > filp->private_data = NULL;
> > + dofree = 0;
>
> Why not initialize it at declaration time?
I wanted to have it protected by mutex_lock() above. However, this also
shall work with the initialization at declaration time.
>
> >
> > /* last close? */
> > spidev->users--;
> > if (!spidev->users) {
> > - int dofree;
> >
> > kfree(spidev->tx_buffer);
> > spidev->tx_buffer = NULL;
> > @@ -628,7 +629,8 @@ static int spidev_release(struct inode *inode,
> > struct file *filp) kfree(spidev);
> > }
> > #ifdef CONFIG_SPI_SLAVE
> > - spi_slave_abort(spidev->spi);
> > + if (!dofree)
> > + spi_slave_abort(spidev->spi);
>
> Can spidev->spi be NULL, if spidev->users != 0?
No, it shouldn't be.
The "dofree" is only set to true (the spidev->spi == NULL condition is
checked) if there are no references (spidev->users == 0).
The if (!dofree) prevents from calling spi_slave_abort() when
spidev->spi == NULL and spidev is kfree'd.
>
> > #endif
> > mutex_unlock(&device_list_lock);
>
> Gr{oetje,eeting}s,
>
> Geert
>
Best regards,
Lukasz Majewski
--
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