2018-06-18 10:54:28

by Arnd Bergmann

Subject: [PATCH] s390: hypfs: use ktime_get_seconds() instead of get_seconds()

time_t and get_seconds() are deprecated because they will overflow on
32-bit architectures in the future. This is not a problem on 64-bit s390,
but we should use proper interfaces anyway.

Besides moving to the time64_t based interface, the CLOCK_MONOTONIC
based ktime_get_seconds() is preferred for kernel internal timekeeping
because it does not behave in unexpected ways during leap second changes
or settimeofday() calls.

Signed-off-by: Arnd Bergmann <[email protected]>
---
arch/s390/hypfs/inode.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/s390/hypfs/inode.c b/arch/s390/hypfs/inode.c
index 06b513d192b9..c681329fdeec 100644
--- a/arch/s390/hypfs/inode.c
+++ b/arch/s390/hypfs/inode.c
@@ -36,7 +36,7 @@ struct hypfs_sb_info {
kuid_t uid; /* uid used for files and dirs */
kgid_t gid; /* gid used for files and dirs */
struct dentry *update_file; /* file to trigger update */
- time_t last_update; /* last update time in secs since 1970 */
+ time64_t last_update; /* last update, CLOCK_MONOTONIC time */
struct mutex lock; /* lock to protect update process */
};

@@ -52,7 +52,7 @@ static void hypfs_update_update(struct super_block *sb)
struct hypfs_sb_info *sb_info = sb->s_fs_info;
struct inode *inode = d_inode(sb_info->update_file);

- sb_info->last_update = get_seconds();
+ sb_info->last_update = ktime_get_seconds();
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
}

@@ -179,7 +179,7 @@ static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
* to restart data collection in this case.
*/
mutex_lock(&fs_info->lock);
- if (fs_info->last_update == get_seconds()) {
+ if (fs_info->last_update == ktime_get_seconds()) {
rc = -EBUSY;
goto out;
}
--
2.9.0

2018-06-18 11:29:01

by Martin Schwidefsky

Subject: Re: [PATCH] s390: hypfs: use ktime_get_seconds() instead of get_seconds()

On Mon, 18 Jun 2018 12:05:00 +0200
Arnd Bergmann <[email protected]> wrote:

> time_t and get_seconds() are deprecated because they will overflow on
> 32-bit architectures in the future. This is not a problem on 64-bit s390,
> but we should use proper interfaces anyway.
>
> Besides moving to the time64_t based interface, the CLOCK_MONOTONIC
> based ktime_get_seconds() is preferred for kernel internal timekeeping
> because it does not behave in unexpected ways during leap second changes
> or settimeofday() calls.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Added to my set of patches for the next merge window.

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.