* [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev
@ 2019-10-01 9:06 Lukasz Majewski
2019-10-01 9:15 ` Geert Uytterhoeven
0 siblings, 1 reply; 6+ messages in thread
From: Lukasz Majewski @ 2019-10-01 9:06 UTC (permalink / raw)
To: Mark Brown, Geert Uytterhoeven
Cc: Colin Ian King, linux-spi, krzk, linux-kernel, Lukasz Majewski,
kbuild test robot, Julia Lawall, Dan Carpenter
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@intel.com>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lukasz Majewski <lukma@denx.de>
---
This fix applies on:
repo: https://kernel.googlesource.com/pub/scm/linux/kernel/git/broonie/spi.git
branch: for-5.4
SHA1: 6b04e47b73f2a0d2c330cecca99f8e2cb8f85b34
---
drivers/spi/spidev.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 3ea9d8a3e6e8..2c6d4dbeebac 100644
--- 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);
#endif
mutex_unlock(&device_list_lock);
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev
2019-10-01 9:06 [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev Lukasz Majewski
@ 2019-10-01 9:15 ` Geert Uytterhoeven
2019-10-01 9:34 ` Lukasz Majewski
0 siblings, 1 reply; 6+ messages in thread
From: Geert Uytterhoeven @ 2019-10-01 9:15 UTC (permalink / raw)
To: Lukasz Majewski
Cc: Mark Brown, Colin Ian King, linux-spi, Krzysztof Kozlowski,
Linux Kernel Mailing List, kbuild test robot, Julia Lawall,
Dan Carpenter
Hi Lukasz,
On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@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 <lkp@intel.com>
> Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
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?
>
> mutex_lock(&device_list_lock);
> spidev = filp->private_data;
> filp->private_data = NULL;
> + dofree = 0;
Why not initialize it 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?
> #endif
> mutex_unlock(&device_list_lock);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev
2019-10-01 9:15 ` Geert Uytterhoeven
@ 2019-10-01 9:34 ` Lukasz Majewski
2019-10-01 10:00 ` Geert Uytterhoeven
0 siblings, 1 reply; 6+ messages in thread
From: Lukasz Majewski @ 2019-10-01 9:34 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Mark Brown, Colin Ian King, linux-spi, Krzysztof Kozlowski,
Linux Kernel Mailing List, kbuild test robot, Julia Lawall,
Dan Carpenter
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Hi Geert,
Thank you for a very prompt response.
> Hi Lukasz,
>
> On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@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 <lkp@intel.com>
> > Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Lukasz Majewski <lukma@denx.de>
>
> 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
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev
2019-10-01 9:34 ` Lukasz Majewski
@ 2019-10-01 10:00 ` Geert Uytterhoeven
2019-10-01 11:07 ` Lukasz Majewski
2019-10-01 11:41 ` Mark Brown
0 siblings, 2 replies; 6+ messages in thread
From: Geert Uytterhoeven @ 2019-10-01 10:00 UTC (permalink / raw)
To: Lukasz Majewski
Cc: Mark Brown, Colin Ian King, linux-spi, Krzysztof Kozlowski,
Linux Kernel Mailing List, kbuild test robot, Julia Lawall,
Dan Carpenter
Hi Lukasz,
On Tue, Oct 1, 2019 at 11:34 AM Lukasz Majewski <lukma@denx.de> wrote:
> > On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@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 <lkp@intel.com>
> > > Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> > > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > Signed-off-by: Lukasz Majewski <lukma@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 -- geert@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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev
2019-10-01 10:00 ` Geert Uytterhoeven
@ 2019-10-01 11:07 ` Lukasz Majewski
2019-10-01 11:41 ` Mark Brown
1 sibling, 0 replies; 6+ messages in thread
From: Lukasz Majewski @ 2019-10-01 11:07 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Mark Brown, Colin Ian King, linux-spi, Krzysztof Kozlowski,
Linux Kernel Mailing List, kbuild test robot, Julia Lawall,
Dan Carpenter
[-- Attachment #1: Type: text/plain, Size: 3653 bytes --]
Hi Geert,
> Hi Lukasz,
>
> On Tue, Oct 1, 2019 at 11:34 AM Lukasz Majewski <lukma@denx.de> wrote:
> > > On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@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 <lkp@intel.com>
> > > > Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> > > > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > > Signed-off-by: Lukasz Majewski <lukma@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.
Yes, this is correct. My other patch [1] clears the FIFOs in SPI IP
block and ends (if there are any stalled) DMA transactions.
>
> I'm wondering if spidev->spi can be NULL if spidev->users is still
> positive.
I think that it cannot.
From my tests [2] - when I do enter spi_slave_abort() function the state
of
spidev->users: 0 dofree: 0 spidev->spi: 0x51337072
So it is possible to call the spidev_release without previously setting
spidev->spi to NULL (which is done in spidev_remove() function).
IMHO the above behavior also seems to be correct, as during distortion
the slave losts synchronization from master.
The spidev_remove() callback is part of spi_device struct and is
called when the device is removed (rmmod spi_fsl_dspi).
From my tests the spidev_release() is NOT called after spidev_remove(),
so the code in former seems to be a dead one.
Or maybe there is an use case which causes calling spidev_release()
after spidev_remove()?
>
> Gr{oetje,eeting}s,
>
> Geert
>
Note:
[1] - https://lkml.org/lkml/2019/9/24/245
[2] -
https://github.com/lmajewski/tests-spi/blob/master/tests/spi/spi_tests.sh
HW setup: HW loopback with two /dev/spidevX.Y devices used
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev
2019-10-01 10:00 ` Geert Uytterhoeven
2019-10-01 11:07 ` Lukasz Majewski
@ 2019-10-01 11:41 ` Mark Brown
1 sibling, 0 replies; 6+ messages in thread
From: Mark Brown @ 2019-10-01 11:41 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Lukasz Majewski, Colin Ian King, linux-spi, Krzysztof Kozlowski,
Linux Kernel Mailing List, kbuild test robot, Julia Lawall,
Dan Carpenter
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On Tue, Oct 01, 2019 at 12:00:07PM +0200, Geert Uytterhoeven wrote:
> On Tue, Oct 1, 2019 at 11:34 AM Lukasz Majewski <lukma@denx.de> wrote:
> > > On Tue, Oct 1, 2019 at 11:07 AM Lukasz Majewski <lukma@denx.de> wrote:
> > 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.
It *shouldn't* be. I think we have other problems if it is.
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2019-10-01 9:06 [PATCH] spi: Avoid calling spi_slave_abort() with kfreed spidev Lukasz Majewski
2019-10-01 9:15 ` Geert Uytterhoeven
2019-10-01 9:34 ` Lukasz Majewski
2019-10-01 10:00 ` Geert Uytterhoeven
2019-10-01 11:07 ` Lukasz Majewski
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