usb: gadget: udc: max3420_udc: fix serialized access
Commit Message
From: Jassi Brar <jaswinder.singh@linaro.org>
The mutex 'spi_bus_mutex' should be used, instead of the spin-lock,
while changing the state of the kernel-thread. Also changing the
usb-gadget state need not be protected by a spin-lock.
This should fix the Smatch static checker warning
warn: sleeping in atomic context
Fixes: 48ba02b2e2b1 ("usb: gadget: add udc driver for max3420")
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
---
drivers/usb/gadget/udc/max3420_udc.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
Comments
On Wed, Feb 08, 2023 at 10:34:18AM -0600, jassisinghbrar@gmail.com wrote:
> From: Jassi Brar <jaswinder.singh@linaro.org>
>
> The mutex 'spi_bus_mutex' should be used, instead of the spin-lock,
> while changing the state of the kernel-thread.
You forgot to say why this is the case.
> Also changing the
> usb-gadget state need not be protected by a spin-lock.
Why not? Why isn't this a separate change?
> This should fix the Smatch static checker warning
> warn: sleeping in atomic context
>
> Fixes: 48ba02b2e2b1 ("usb: gadget: add udc driver for max3420")
> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
> ---
> drivers/usb/gadget/udc/max3420_udc.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
You forgot a "Reported-by:" line, right?
And odd indentation in your changelog text.
thanks,
greg k-h
On Wed, Feb 08, 2023 at 10:34:18AM -0600, jassisinghbrar@gmail.com wrote:
> From: Jassi Brar <jaswinder.singh@linaro.org>
Also, housekeeping issue, I know Linaro has good email servers, please
use them and not gmail accounts to send patches so that we can validate
that you really are the correct author.
thanks,
greg k-h
On Wed, 8 Feb 2023 at 11:23, Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Wed, Feb 08, 2023 at 10:34:18AM -0600, jassisinghbrar@gmail.com wrote:
> > From: Jassi Brar <jaswinder.singh@linaro.org>
> >
> > The mutex 'spi_bus_mutex' should be used, instead of the spin-lock,
> > while changing the state of the kernel-thread.
>
> You forgot to say why this is the case.
>
It was 'inherited' (my fault) from drivers/usb/host/max3421-hcd.c
which has the same issue.
OK, I will also add to the log why that is a bad idea.
> > Also changing the
> > usb-gadget state need not be protected by a spin-lock.
>
> Why not? Why isn't this a separate change?
>
Because other low-level spi changes are protected by spin-lock and it
seems ok to not to have to worry about such a race.
I don't have the h/w anymore to actually test it, so it is just a
patch from looking.
I just got lazy to break it into two patches, will do that.
> > This should fix the Smatch static checker warning
> > warn: sleeping in atomic context
> >
> > Fixes: 48ba02b2e2b1 ("usb: gadget: add udc driver for max3420")
> > Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
> > ---
> > drivers/usb/gadget/udc/max3420_udc.c | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
>
> You forgot a "Reported-by:" line, right?
>
Yes, I forgot.
thanks.
@@ -501,13 +501,16 @@ static irqreturn_t max3420_vbus_handler(int irq, void *dev_id)
unsigned long flags;
spin_lock_irqsave(&udc->lock, flags);
+
/* its a vbus change interrupt */
udc->vbus_active = !udc->vbus_active;
udc->todo |= UDC_START;
+
+ spin_unlock_irqrestore(&udc->lock, flags);
+
usb_udc_vbus_handler(&udc->gadget, udc->vbus_active);
usb_gadget_set_state(&udc->gadget, udc->vbus_active
? USB_STATE_POWERED : USB_STATE_NOTATTACHED);
- spin_unlock_irqrestore(&udc->lock, flags);
if (udc->thread_task)
wake_up_process(udc->thread_task);
@@ -1298,15 +1301,14 @@ static int max3420_probe(struct spi_device *spi)
static void max3420_remove(struct spi_device *spi)
{
struct max3420_udc *udc = spi_get_drvdata(spi);
- unsigned long flags;
usb_del_gadget_udc(&udc->gadget);
- spin_lock_irqsave(&udc->lock, flags);
+ mutex_lock(&udc->spi_bus_mutex);
kthread_stop(udc->thread_task);
- spin_unlock_irqrestore(&udc->lock, flags);
+ mutex_unlock(&udc->spi_bus_mutex);
}
static const struct of_device_id max3420_udc_of_match[] = {