Re: [Xen-devel] [PATCH 04/12] xen: make use of xenbus_read_unsigned() in xen-tpmfront

[Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>]

On Mon, Oct 31, 2016 at 05:48:22PM +0100, Juergen Gross wrote:
> Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
> This requires to change the type of one read from int to unsigned,
> but this case has been wrong before: negative values are not allowed
> for the modified case.
> 
> Cc: peterhuewe@xxxxxx
> Cc: tpmdd@xxxxxxxxxxxx
> Cc: jarkko.sakkinen@xxxxxxxxxxxxxxx
> Cc: jgunthorpe@xxxxxxxxxxxxxxxxxxxx
> Cc: tpmdd-devel@xxxxxxxxxxxxxxxxxxxxx
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

/Jarkko

> ---
>  drivers/char/tpm/xen-tpmfront.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
> index 62028f4..50072cc 100644
> --- a/drivers/char/tpm/xen-tpmfront.c
> +++ b/drivers/char/tpm/xen-tpmfront.c
> @@ -337,18 +337,14 @@ static int tpmfront_resume(struct xenbus_device *dev)
>  static void backend_changed(struct xenbus_device *dev,
>               enum xenbus_state backend_state)
>  {
> -     int val;
> -
>       switch (backend_state) {
>       case XenbusStateInitialised:
>       case XenbusStateConnected:
>               if (dev->state == XenbusStateConnected)
>                       break;
>  
> -             if (xenbus_scanf(XBT_NIL, dev->otherend,
> -                             "feature-protocol-v2", "%d", &val) < 0)
> -                     val = 0;
> -             if (!val) {
> +             if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
> +                                       0)) {
>                       xenbus_dev_fatal(dev, -EINVAL,
>                                       "vTPM protocol 2 required");
>                       return;
> -- 
> 2.6.6
> 

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