Re: [RFC PATCH v2 1/4] y2038: add 64bit time_t support in timeval for 32bit architecture

From: Bamvor Zhang Jian
Date: Thu Jul 09 2015 - 05:03:10 EST


Hi, John

On 07/09/2015 04:09 AM, John Stultz wrote:
On Mon, Jun 29, 2015 at 7:23 AM, Bamvor Zhang Jian
<bamvor.zhangjian@xxxxxxxxxx> wrote:
+int get_timeval64(struct timeval64 *tv,
+ const struct __kernel_timeval __user *utv)
+{
+ struct __kernel_timeval ktv;
+ int ret;
+
+ ret = copy_from_user(&ktv, utv, sizeof(ktv));
+ if (ret)
+ return -EFAULT;
+
+ tv->tv_sec = ktv.tv_sec;
+ if (!IS_ENABLED(CONFIG_64BIT)
+#ifdef CONFIG_COMPAT
+ || is_compat_task()
+#endif

These sorts of ifdefs are to be avoided inside of functions.

Instead, it seems is_compat_task() should be defined to 0 in the
!CONFIG_COMPAT case, so you can avoid the ifdefs and the compiler can
still optimize it out.
I add this ifdef because I got compile failure on arm platform. This
file do not include the <linux/compat.h> directly. And in arm64,
compat.h is included implicitily.
So, I am not sure what I should do here. Include <linux/compat.h> in
this file directly or add a this check at the beginning of this file?

#ifndef is_compat_task
#define is_compat_task() (0)
#endif

Otherwise this looks similar to a patch Baolin (cc'ed) has been working on.
Yes.

regards

bamvor

thanks
-john

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