Re: [PATCH 03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[Greg Kroah-Hartman]

On Fri, May 18, 2018 at 10:48:30PM +0300, Andy Shevchenko wrote:
> On Thu, May 17, 2018 at 8:03 PM, Guido Kiener  
> wrote:
> > Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
> > get/set I/O timeout for specific file handle.
> 
> 
> 
> 
> > +static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
> > +   void __user *arg)
> > +{
> > +   __u32 timeout;
> > +
> > +   timeout = file_data->timeout;
> 
> Why do you need __u32 on kernel side?
> Would plain u32 work?

Yes, on the kernel side that is the correct type to use after you copy
it over from userspace.

thanks,

greg k-h
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Re: [PATCH 03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[guido]

Zitat von Andy Shevchenko :

On Thu, May 17, 2018 at 8:03 PM, Guido Kiener  
 wrote:

Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
get/set I/O timeout for specific file handle.






+static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
+   void __user *arg)
+{
+   __u32 timeout;
+
+   timeout = file_data->timeout;


Why do you need __u32 on kernel side?
Would plain u32 work?


It compiles and links with u32 and __u32 (and even double). AFAIK __u32 is for
user code and u32 for kernel code. So, correct is here what the  
maintainer says

or experienced kernel developers :-).
My opinion here is that put_user(..) and get_user(..) should always  
copy to the

same type to always have a safe copy operation from/to userland. So I prefer
__u32.

If you are sure that u32 is more correct here, then we use u32.

Best regards,

Guido




+
+   return put_user(timeout, (__u32 __user *)arg);
+}



+static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
+   void __user *arg)
+{
+   __u32 timeout;


Ditto.


+   return 0;
+}



--
With Best Regards,
Andy Shevchenko




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Re: [PATCH 03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[Andy Shevchenko]

On Thu, May 17, 2018 at 8:03 PM, Guido Kiener  wrote:
> Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
> get/set I/O timeout for specific file handle.




> +static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
> +   void __user *arg)
> +{
> +   __u32 timeout;
> +
> +   timeout = file_data->timeout;

Why do you need __u32 on kernel side?
Would plain u32 work?

> +
> +   return put_user(timeout, (__u32 __user *)arg);
> +}

> +static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
> +   void __user *arg)
> +{
> +   __u32 timeout;

Ditto.

> +   return 0;
> +}


-- 
With Best Regards,
Andy Shevchenko
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Re: [PATCH 03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[guido]

Zitat von Greg KH :


On Thu, May 17, 2018 at 07:03:27PM +0200, Guido Kiener wrote:

Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
get/set I/O timeout for specific file handle.

Different operations on an instrument can take different lengths of
time thus it is important to be able to set the timeout slightly
longer than the expected duration of each operation to optimise the
responsiveness of the application. As the instrument may be shared by
multiple applications the timeout should be settable on a per file
descriptor basis.

Tested-by: Dave Penkler 
Reviewed-by: Steve Bayless 
Signed-off-by: Dave Penkler 
Signed-off-by: Guido Kiener 
---
 drivers/usb/class/usbtmc.c   | 58 +---
 include/uapi/linux/usb/tmc.h |  2 ++
 2 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 5754354429d8..ad7872003420 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -30,6 +30,8 @@
  */
 #define USBTMC_SIZE_IOBUFFER   2048

+/* Minimum USB timeout (in milliseconds) */
+#define USBTMC_MIN_TIMEOUT 100
 /* Default USB timeout (in milliseconds) */
 #define USBTMC_TIMEOUT 5000

@@ -116,6 +118,7 @@ struct usbtmc_file_data {
struct usbtmc_device_data *data;
struct list_head file_elem;

+   u32timeout;
u8 srq_byte;
atomic_t   srq_asserted;

@@ -163,6 +166,7 @@ static int usbtmc_open(struct inode *inode,  
struct file *filp)

file_data->data = data;

/* copy default values from device settings */
+   file_data->timeout = USBTMC_TIMEOUT;
file_data->TermChar = data->TermChar;
file_data->TermCharEnabled = data->TermCharEnabled;
file_data->auto_abort = data->auto_abort;
@@ -478,7 +482,7 @@ static int usbtmc488_ioctl_read_stb(struct  
usbtmc_file_data *file_data,

rv = wait_event_interruptible_timeout(
data->waitq,
atomic_read(>iin_data_valid) != 0,
-   USBTMC_TIMEOUT);
+   file_data->timeout);
if (rv < 0) {
dev_dbg(dev, "wait interrupted %d\n", rv);
goto exit;
@@ -613,7 +617,8 @@ static int send_request_dev_dep_msg_in(struct  
usbtmc_file_data *file_data,

retval = usb_bulk_msg(data->usb_dev,
  usb_sndbulkpipe(data->usb_dev,
  data->bulk_out),
- buffer, USBTMC_HEADER_SIZE, , 
USBTMC_TIMEOUT);
+ buffer, USBTMC_HEADER_SIZE,
+ , file_data->timeout);

/* Store bTag (in case we need to abort) */
data->bTag_last_write = data->bTag;
@@ -681,7 +686,7 @@ static ssize_t usbtmc_read(struct file *filp,  
char __user *buf,

  usb_rcvbulkpipe(data->usb_dev,
  data->bulk_in),
  buffer, USBTMC_SIZE_IOBUFFER, ,
- USBTMC_TIMEOUT);
+ file_data->timeout);

 		dev_dbg(dev, "usb_bulk_msg: retval(%u), done(%zu),  
remaining(%zu), actual(%d)\n", retval, done, remaining, actual);


@@ -854,7 +859,7 @@ static ssize_t usbtmc_write(struct file *filp,  
const char __user *buf,

  usb_sndbulkpipe(data->usb_dev,
  data->bulk_out),
  buffer, n_bytes,
- , USBTMC_TIMEOUT);
+ , file_data->timeout);
if (retval != 0)
break;
n_bytes -= actual;
@@ -1211,6 +1216,41 @@ static int  
usbtmc_ioctl_indicator_pulse(struct usbtmc_device_data *data)

return rv;
 }

+/*
+ * Get the usb timeout value
+ */
+static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
+   void __user *arg)
+{
+   __u32 timeout;
+
+   timeout = file_data->timeout;
+
+   return put_user(timeout, (__u32 __user *)arg);
+}
+
+/*
+ * Set the usb timeout value
+ */
+static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
+   void __user *arg)
+{
+   __u32 timeout;
+
+   if (get_user(timeout, (__u32 __user *)arg))
+   return -EFAULT;
+
+   /* Note that timeout = 0 means
+* MAX_SCHEDULE_TIMEOUT in usb_control_msg
+*/
+   if (timeout < USBTMC_MIN_TIMEOUT)
+   return -EINVAL;
+
+   file_data->timeout = timeout;
+
+   

Re: [PATCH 03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[Greg KH]

On Thu, May 17, 2018 at 07:03:27PM +0200, Guido Kiener wrote:
> Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
> get/set I/O timeout for specific file handle.
> 
> Different operations on an instrument can take different lengths of
> time thus it is important to be able to set the timeout slightly
> longer than the expected duration of each operation to optimise the
> responsiveness of the application. As the instrument may be shared by
> multiple applications the timeout should be settable on a per file
> descriptor basis.
> 
> Tested-by: Dave Penkler 
> Reviewed-by: Steve Bayless 
> Signed-off-by: Dave Penkler 
> Signed-off-by: Guido Kiener 
> ---
>  drivers/usb/class/usbtmc.c   | 58 +---
>  include/uapi/linux/usb/tmc.h |  2 ++
>  2 files changed, 56 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
> index 5754354429d8..ad7872003420 100644
> --- a/drivers/usb/class/usbtmc.c
> +++ b/drivers/usb/class/usbtmc.c
> @@ -30,6 +30,8 @@
>   */
>  #define USBTMC_SIZE_IOBUFFER 2048
>  
> +/* Minimum USB timeout (in milliseconds) */
> +#define USBTMC_MIN_TIMEOUT   100
>  /* Default USB timeout (in milliseconds) */
>  #define USBTMC_TIMEOUT   5000
>  
> @@ -116,6 +118,7 @@ struct usbtmc_file_data {
>   struct usbtmc_device_data *data;
>   struct list_head file_elem;
>  
> + u32timeout;
>   u8 srq_byte;
>   atomic_t   srq_asserted;
>  
> @@ -163,6 +166,7 @@ static int usbtmc_open(struct inode *inode, struct file 
> *filp)
>   file_data->data = data;
>  
>   /* copy default values from device settings */
> + file_data->timeout = USBTMC_TIMEOUT;
>   file_data->TermChar = data->TermChar;
>   file_data->TermCharEnabled = data->TermCharEnabled;
>   file_data->auto_abort = data->auto_abort;
> @@ -478,7 +482,7 @@ static int usbtmc488_ioctl_read_stb(struct 
> usbtmc_file_data *file_data,
>   rv = wait_event_interruptible_timeout(
>   data->waitq,
>   atomic_read(>iin_data_valid) != 0,
> - USBTMC_TIMEOUT);
> + file_data->timeout);
>   if (rv < 0) {
>   dev_dbg(dev, "wait interrupted %d\n", rv);
>   goto exit;
> @@ -613,7 +617,8 @@ static int send_request_dev_dep_msg_in(struct 
> usbtmc_file_data *file_data,
>   retval = usb_bulk_msg(data->usb_dev,
> usb_sndbulkpipe(data->usb_dev,
> data->bulk_out),
> -   buffer, USBTMC_HEADER_SIZE, , 
> USBTMC_TIMEOUT);
> +   buffer, USBTMC_HEADER_SIZE,
> +   , file_data->timeout);
>  
>   /* Store bTag (in case we need to abort) */
>   data->bTag_last_write = data->bTag;
> @@ -681,7 +686,7 @@ static ssize_t usbtmc_read(struct file *filp, char __user 
> *buf,
> usb_rcvbulkpipe(data->usb_dev,
> data->bulk_in),
> buffer, USBTMC_SIZE_IOBUFFER, ,
> -   USBTMC_TIMEOUT);
> +   file_data->timeout);
>  
>   dev_dbg(dev, "usb_bulk_msg: retval(%u), done(%zu), 
> remaining(%zu), actual(%d)\n", retval, done, remaining, actual);
>  
> @@ -854,7 +859,7 @@ static ssize_t usbtmc_write(struct file *filp, const char 
> __user *buf,
> usb_sndbulkpipe(data->usb_dev,
> data->bulk_out),
> buffer, n_bytes,
> -   , USBTMC_TIMEOUT);
> +   , file_data->timeout);
>   if (retval != 0)
>   break;
>   n_bytes -= actual;
> @@ -1211,6 +1216,41 @@ static int usbtmc_ioctl_indicator_pulse(struct 
> usbtmc_device_data *data)
>   return rv;
>  }
>  
> +/*
> + * Get the usb timeout value
> + */
> +static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
> + void __user *arg)
> +{
> + __u32 timeout;
> +
> + timeout = file_data->timeout;
> +
> + return put_user(timeout, (__u32 __user *)arg);
> +}
> +
> +/*
> + * Set the usb timeout value
> + */
> +static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
> + void __user *arg)
> +{
> + __u32 timeout;
> +
> + if (get_user(timeout, (__u32 __user *)arg))
> + return -EFAULT;
> +
> + /* Note that timeout = 0 means
> +  * MAX_SCHEDULE_TIMEOUT in usb_control_msg
> +  */
> + if (timeout <