[PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
Currently the I/O buffer is allocated part of the device status
structure, potentially sharing the same cache line with other members
in this structure.
Allocate the buffer separately, to avoid the I/O operations corrupting
the device status structure due to cache line sharing.
Compiled tested only as I don't have access to hardware.
Signed-off-by: Octavian Purdila
---
drivers/mfd/viperboard.c | 8
include/linux/mfd/viperboard.h | 2 +-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
index e00f534..5f62f4e 100644
--- a/drivers/mfd/viperboard.c
+++ b/drivers/mfd/viperboard.c
@@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface,
return -ENOMEM;
}
+ vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
+ if (vb->buf == NULL) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
mutex_init(&vb->lock);
vb->usb_dev = usb_get_dev(interface_to_usbdev(interface));
@@ -105,6 +111,7 @@ static int vprbrd_probe(struct usb_interface *interface,
error:
if (vb) {
usb_put_dev(vb->usb_dev);
+ kfree(vb->buf);
kfree(vb);
}
@@ -118,6 +125,7 @@ static void vprbrd_disconnect(struct usb_interface
*interface)
mfd_remove_devices(&interface->dev);
usb_set_intfdata(interface, NULL);
usb_put_dev(vb->usb_dev);
+ kfree(vb->buf);
kfree(vb);
dev_dbg(&interface->dev, "disconnected\n");
diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
index 1934528..af928d0 100644
--- a/include/linux/mfd/viperboard.h
+++ b/include/linux/mfd/viperboard.h
@@ -103,7 +103,7 @@ struct vprbrd_i2c_addr_msg {
struct vprbrd {
struct usb_device *usb_dev; /* the usb device for this device */
struct mutex lock;
- u8 buf[sizeof(struct vprbrd_i2c_write_msg)];
+ u8 *buf;
struct platform_device pdev;
};
--
1.9.1
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Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Mon, Sep 22, 2014 at 10:39:18PM +0300, Octavian Purdila wrote:
> Currently the I/O buffer is allocated part of the device status
> structure, potentially sharing the same cache line with other members
> in this structure.
>
> Allocate the buffer separately, to avoid the I/O operations corrupting
> the device status structure due to cache line sharing.
>
> Compiled tested only as I don't have access to hardware.
>
> Signed-off-by: Octavian Purdila
> ---
> drivers/mfd/viperboard.c | 8
> include/linux/mfd/viperboard.h | 2 +-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
> index e00f534..5f62f4e 100644
> --- a/drivers/mfd/viperboard.c
> +++ b/drivers/mfd/viperboard.c
> @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface,
> return -ENOMEM;
> }
>
> + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
> + if (vb->buf == NULL) {
> + ret = -ENOMEM;
> + goto error;
This will cause a kref imbalance as you have a usb_put_dev in error,
but haven't done the get yet.
> + }
> +
> mutex_init(&vb->lock);
>
> vb->usb_dev = usb_get_dev(interface_to_usbdev(interface));
Here's the get.
Johan
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Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Tue, Sep 23, 2014 at 09:35:41AM +0200, Johan Hovold wrote:
> On Mon, Sep 22, 2014 at 10:39:18PM +0300, Octavian Purdila wrote:
> > Currently the I/O buffer is allocated part of the device status
> > structure, potentially sharing the same cache line with other members
> > in this structure.
> >
> > Allocate the buffer separately, to avoid the I/O operations corrupting
> > the device status structure due to cache line sharing.
> >
> > Compiled tested only as I don't have access to hardware.
> >
> > Signed-off-by: Octavian Purdila
> > ---
> > drivers/mfd/viperboard.c | 8
> > include/linux/mfd/viperboard.h | 2 +-
> > 2 files changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
> > index e00f534..5f62f4e 100644
> > --- a/drivers/mfd/viperboard.c
> > +++ b/drivers/mfd/viperboard.c
> > @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface,
> > return -ENOMEM;
> > }
> >
> > + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
> > + if (vb->buf == NULL) {
> > + ret = -ENOMEM;
> > + goto error;
>
> This will cause a kref imbalance as you have a usb_put_dev in error,
> but haven't done the get yet.
Nevermind. This isn't problem as the usb device is null.
Haven't had my morning coffee yet. ;)
Johan
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Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Mon, Sep 22, 2014 at 10:39:18PM +0300, Octavian Purdila wrote:
> Currently the I/O buffer is allocated part of the device status
> structure, potentially sharing the same cache line with other members
> in this structure.
>
> Allocate the buffer separately, to avoid the I/O operations corrupting
> the device status structure due to cache line sharing.
>
> Compiled tested only as I don't have access to hardware.
>
> Signed-off-by: Octavian Purdila
Reviewed-by: Johan Hovold
> ---
> drivers/mfd/viperboard.c | 8
> include/linux/mfd/viperboard.h | 2 +-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
> index e00f534..5f62f4e 100644
> --- a/drivers/mfd/viperboard.c
> +++ b/drivers/mfd/viperboard.c
> @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface,
> return -ENOMEM;
> }
>
> + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
> + if (vb->buf == NULL) {
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> mutex_init(&vb->lock);
>
> vb->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> @@ -105,6 +111,7 @@ static int vprbrd_probe(struct usb_interface *interface,
> error:
> if (vb) {
> usb_put_dev(vb->usb_dev);
> + kfree(vb->buf);
> kfree(vb);
> }
>
> @@ -118,6 +125,7 @@ static void vprbrd_disconnect(struct usb_interface
> *interface)
> mfd_remove_devices(&interface->dev);
> usb_set_intfdata(interface, NULL);
> usb_put_dev(vb->usb_dev);
> + kfree(vb->buf);
> kfree(vb);
>
> dev_dbg(&interface->dev, "disconnected\n");
> diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
> index 1934528..af928d0 100644
> --- a/include/linux/mfd/viperboard.h
> +++ b/include/linux/mfd/viperboard.h
> @@ -103,7 +103,7 @@ struct vprbrd_i2c_addr_msg {
> struct vprbrd {
> struct usb_device *usb_dev; /* the usb device for this device */
> struct mutex lock;
> - u8 buf[sizeof(struct vprbrd_i2c_write_msg)];
> + u8 *buf;
> struct platform_device pdev;
> };
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Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Mon, 22 Sep 2014, Octavian Purdila wrote:
> Currently the I/O buffer is allocated part of the device status
> structure, potentially sharing the same cache line with other members
> in this structure.
>
> Allocate the buffer separately, to avoid the I/O operations corrupting
> the device status structure due to cache line sharing.
>
> Compiled tested only as I don't have access to hardware.
>
> Signed-off-by: Octavian Purdila
> ---
> drivers/mfd/viperboard.c | 8
> include/linux/mfd/viperboard.h | 2 +-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
> index e00f534..5f62f4e 100644
> --- a/drivers/mfd/viperboard.c
> +++ b/drivers/mfd/viperboard.c
> @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface,
> return -ENOMEM;
> }
>
> + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
Can you obtain the 'struct device' first then use managed resources
(devm_*)?
> + if (vb->buf == NULL) {
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> mutex_init(&vb->lock);
>
> vb->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> @@ -105,6 +111,7 @@ static int vprbrd_probe(struct usb_interface *interface,
> error:
> if (vb) {
> usb_put_dev(vb->usb_dev);
> + kfree(vb->buf);
Then you don't need this.
> kfree(vb);
> }
>
> @@ -118,6 +125,7 @@ static void vprbrd_disconnect(struct usb_interface
> *interface)
> mfd_remove_devices(&interface->dev);
> usb_set_intfdata(interface, NULL);
> usb_put_dev(vb->usb_dev);
> + kfree(vb->buf);
Or this.
> kfree(vb);
>
> dev_dbg(&interface->dev, "disconnected\n");
> diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
> index 1934528..af928d0 100644
> --- a/include/linux/mfd/viperboard.h
> +++ b/include/linux/mfd/viperboard.h
> @@ -103,7 +103,7 @@ struct vprbrd_i2c_addr_msg {
> struct vprbrd {
> struct usb_device *usb_dev; /* the usb device for this device */
> struct mutex lock;
> - u8 buf[sizeof(struct vprbrd_i2c_write_msg)];
> + u8 *buf;
> struct platform_device pdev;
> };
>
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Wed, Sep 24, 2014 at 11:12:06AM +0100, Lee Jones wrote: > On Mon, 22 Sep 2014, Octavian Purdila wrote: > > > Currently the I/O buffer is allocated part of the device status > > structure, potentially sharing the same cache line with other members > > in this structure. > > > > Allocate the buffer separately, to avoid the I/O operations corrupting > > the device status structure due to cache line sharing. > > > > Compiled tested only as I don't have access to hardware. > > > > Signed-off-by: Octavian Purdila > > --- > > drivers/mfd/viperboard.c | 8 > > include/linux/mfd/viperboard.h | 2 +- > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c > > index e00f534..5f62f4e 100644 > > --- a/drivers/mfd/viperboard.c > > +++ b/drivers/mfd/viperboard.c > > @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface, > > return -ENOMEM; > > } > > > > + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL); > > Can you obtain the 'struct device' first then use managed resources > (devm_*)? I think any devres conversion should be done in a follow-up patch and not be included in the fix (e.g. in order to facilitate backporting). We also don't want to mix allocation schemes. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Wed, 24 Sep 2014, Johan Hovold wrote: > On Wed, Sep 24, 2014 at 11:12:06AM +0100, Lee Jones wrote: > > On Mon, 22 Sep 2014, Octavian Purdila wrote: > > > > > Currently the I/O buffer is allocated part of the device status > > > structure, potentially sharing the same cache line with other members > > > in this structure. > > > > > > Allocate the buffer separately, to avoid the I/O operations corrupting > > > the device status structure due to cache line sharing. > > > > > > Compiled tested only as I don't have access to hardware. > > > > > > Signed-off-by: Octavian Purdila > > > --- > > > drivers/mfd/viperboard.c | 8 > > > include/linux/mfd/viperboard.h | 2 +- > > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c > > > index e00f534..5f62f4e 100644 > > > --- a/drivers/mfd/viperboard.c > > > +++ b/drivers/mfd/viperboard.c > > > @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface > > > *interface, > > > return -ENOMEM; > > > } > > > > > > + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL); > > > > Can you obtain the 'struct device' first then use managed resources > > (devm_*)? > > I think any devres conversion should be done in a follow-up patch and > not be included in the fix (e.g. in order to facilitate backporting). We > also don't want to mix allocation schemes. I agree, but equally I'm not keen on accepting this patch as I believe it could be done better. Please submit two patches, one converting to shared resources and this being the subsequent one, fixed up to do the right thing. -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Wed, Sep 24, 2014 at 01:00:02PM +0100, Lee Jones wrote: > On Wed, 24 Sep 2014, Johan Hovold wrote: > > > On Wed, Sep 24, 2014 at 11:12:06AM +0100, Lee Jones wrote: > > > On Mon, 22 Sep 2014, Octavian Purdila wrote: > > > > > > > Currently the I/O buffer is allocated part of the device status > > > > structure, potentially sharing the same cache line with other members > > > > in this structure. > > > > > > > > Allocate the buffer separately, to avoid the I/O operations corrupting > > > > the device status structure due to cache line sharing. > > > > > > > > Compiled tested only as I don't have access to hardware. > > > > > > > > Signed-off-by: Octavian Purdila > > > > --- > > > > drivers/mfd/viperboard.c | 8 > > > > include/linux/mfd/viperboard.h | 2 +- > > > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c > > > > index e00f534..5f62f4e 100644 > > > > --- a/drivers/mfd/viperboard.c > > > > +++ b/drivers/mfd/viperboard.c > > > > @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface > > > > *interface, > > > > return -ENOMEM; > > > > } > > > > > > > > + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), > > > > GFP_KERNEL); > > > > > > Can you obtain the 'struct device' first then use managed resources > > > (devm_*)? > > > > I think any devres conversion should be done in a follow-up patch and > > not be included in the fix (e.g. in order to facilitate backporting). We > > also don't want to mix allocation schemes. > > I agree, but equally I'm not keen on accepting this patch as I believe > it could be done better. > > Please submit two patches, one converting to shared resources and this > being the subsequent one, fixed up to do the right thing. A buffer-corruption fix is a candidate for stable, whereas a devres conversion (clean up) is not. Hence the former should not depend on the latter. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Wed, Sep 24, 2014 at 3:26 PM, Johan Hovold wrote: > On Wed, Sep 24, 2014 at 01:00:02PM +0100, Lee Jones wrote: >> On Wed, 24 Sep 2014, Johan Hovold wrote: >> >> > On Wed, Sep 24, 2014 at 11:12:06AM +0100, Lee Jones wrote: >> > > On Mon, 22 Sep 2014, Octavian Purdila wrote: >> > > >> > > > Currently the I/O buffer is allocated part of the device status >> > > > structure, potentially sharing the same cache line with other members >> > > > in this structure. >> > > > >> > > > Allocate the buffer separately, to avoid the I/O operations corrupting >> > > > the device status structure due to cache line sharing. >> > > > >> > > > Compiled tested only as I don't have access to hardware. >> > > > >> > > > Signed-off-by: Octavian Purdila >> > > > --- >> > > > drivers/mfd/viperboard.c | 8 >> > > > include/linux/mfd/viperboard.h | 2 +- >> > > > 2 files changed, 9 insertions(+), 1 deletion(-) >> > > > >> > > > diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c >> > > > index e00f534..5f62f4e 100644 >> > > > --- a/drivers/mfd/viperboard.c >> > > > +++ b/drivers/mfd/viperboard.c >> > > > @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface >> > > > *interface, >> > > > return -ENOMEM; >> > > > } >> > > > >> > > > + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), >> > > > GFP_KERNEL); >> > > >> > > Can you obtain the 'struct device' first then use managed resources >> > > (devm_*)? >> > >> > I think any devres conversion should be done in a follow-up patch and >> > not be included in the fix (e.g. in order to facilitate backporting). We >> > also don't want to mix allocation schemes. >> >> I agree, but equally I'm not keen on accepting this patch as I believe >> it could be done better. >> >> Please submit two patches, one converting to shared resources and this >> being the subsequent one, fixed up to do the right thing. > > A buffer-corruption fix is a candidate for stable, whereas a devres > conversion (clean up) is not. Hence the former should not depend on the > latter. > I can follow-up with a v3 3 patch series: first for the fix, second for the OOM & error path cleanup, third for devm conversion. I think this will address both issues (backport and better final result). -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately
On Wed, Sep 24, 2014 at 03:34:08PM +0300, Octavian Purdila wrote: > I can follow-up with a v3 3 patch series: first for the fix, second > for the OOM & error path cleanup, third for devm conversion. I'd include the error-path clean up bit in the devres conversion as that is what it's really all about. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
