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 octavian.purd...@intel.com
---
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 octavian.purd...@intel.com --- 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 octavian.purd...@intel.com --- 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 octavian.purd...@intel.com --- 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 jo...@kernel.org 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 octavian.purd...@intel.com --- 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
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 octavian.purd...@intel.com
---
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 octavian.purd...@intel.com
---
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 octavian.purd...@intel.com
Reviewed-by: Johan Hovold jo...@kernel.org
---
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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[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 octavian.purd...@intel.com
---
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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