Re: [patch 3/4] timerfd: Implement timerfd_ioctl method to restore timerfd_ctx::ticks

On Wednesday 02 July 2014 21:04:16 Cyrill Gorcunov wrote:

On Wed, Jul 02, 2014 at 12:49:51PM -0400, Christopher Covington wrote:

quoted

quoted

 
+#ifdef CONFIG_CHECKPOINT_RESTORE
+static long timerfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+   struct timerfd_ctx *ctx = file->private_data;
+   int ret = 0;
+
+   switch (cmd) {
+   case TFD_IOC_SET_TICKS: {
+           u64 ticks;
+
+           if (get_user(ticks, (u64 __user *)arg))

64-bit get_user is currently unsupported on ARM, although it appears work is
ongoing [1].

1. https://lkml.org/lkml/2014/6/17/260

Thanks for info, Christopher! What arm camp is using then, copy-from-user?

copy_from_user should work on all architectures. I believe a 64-bit get_user
is currently unsupported on most 32-bit architectures, x86-32 being a notable
exception.

	Arnd