Re: [Xen-devel] [PATCH v2] xen/pcifront: Remove usage of struct timeval

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/19/2015 02:08 AM, Tina Ruchandani wrote:
> struct timeval uses a 32-bit field for representing seconds,
> which will overflow in the year 2038 and beyond. This patch replaces
> struct timeval with 64-bit ktime_t which is 2038 safe.
> The patch is part of a larger effort to remove instances of
> 32-bit timekeeping variables (timeval, time_t and timespec)
> from the kernel.
>
> Signed-off-by: Tina Ruchandani <ruchandani.tina@xxxxxxxxx>
> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>


> --
> Changes in v2:
> - Use monotonic time (ktime_get_ns()) instead of real time
> since we only care about elapsed delta here.
> - Use macro ktime_get_ns() instead of getting ktime_t and
> converting it to ns.
> ---
>   drivers/pci/xen-pcifront.c | 8 +++-----
>   1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
> index 7cfd2db..c4796c8 100644
> --- a/drivers/pci/xen-pcifront.c
> +++ b/drivers/pci/xen-pcifront.c
> @@ -20,6 +20,7 @@
>   #include <linux/workqueue.h>
>   #include <linux/bitops.h>
>   #include <linux/time.h>
> +#include <linux/ktime.h>
>   #include <xen/platform_pci.h>
>   
>   #include <asm/xen/swiotlb-xen.h>
> @@ -115,7 +116,6 @@ static int do_pci_op(struct pcifront_device *pdev, struct 
> xen_pci_op *op)
>         evtchn_port_t port = pdev->evtchn;
>         unsigned irq = pdev->irq;
>         s64 ns, ns_timeout;
> -       struct timeval tv;
>   
>   	spin_lock_irqsave(&pdev->sh_info_lock, irq_flags);
>   
> @@ -132,8 +132,7 @@ static int do_pci_op(struct pcifront_device *pdev, struct xen_pci_op *op)
>          * (in the latter case we end up continually re-executing poll() with a
>          * timeout in the past). 1s difference gives plenty of slack for error.
>          */
> -       do_gettimeofday(&tv);
> -       ns_timeout = timeval_to_ns(&tv) + 2 * (s64)NSEC_PER_SEC;
> +       ns_timeout = ktime_get_ns() + 2 * (s64)NSEC_PER_SEC;
>   
>   	xen_clear_irq_pending(irq);
>   
> @@ -141,8 +140,7 @@ static int do_pci_op(struct pcifront_device *pdev, struct xen_pci_op *op)
>                         (unsigned long *)&pdev->sh_info->flags)) {
>                 xen_poll_irq_timeout(irq, jiffies + 3*HZ);
>                 xen_clear_irq_pending(irq);
> -               do_gettimeofday(&tv);
> -               ns = timeval_to_ns(&tv);
> +               ns = ktime_get_ns();
>                 if (ns > ns_timeout) {
>                         dev_err(&pdev->xdev->dev,
>                                 "pciback not responding!!!\n");

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