Hi Lukasz,
On Tue, Oct 1, 2019 at 11:34 AM Lukasz Majewski <lu...@denx.de> wrote:
> > On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lu...@denx.de> 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 <l...@intel.com>
> > > Reported-by: Julia Lawall <julia.law...@lip6.fr>
> > > Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
> > > Signed-off-by: Lukasz Majewski <lu...@denx.de>
> > > --- 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;
> > >
> > > mutex_lock(&device_list_lock);
> > > spidev = filp->private_data;
> > > filp->private_data = NULL;
> > > + dofree = 0;
> > >
> > > /* 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.
If spidev->users != 0, the block checking spidev->spi == NULL is never
executed, and spi_slave_abort() will be called.
I'm wondering if spidev->spi can be NULL if spidev->users is still positive.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
