Commit 94d440d6 authored by Andrei Vagin's avatar Andrei Vagin Committed by Thomas Gleixner

proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets

Michael Kerrisk suggested to replace numeric clock IDs with symbolic names.

Now the content of these files looks like this:
$ cat /proc/774/timens_offsets
monotonic      864000         0
boottime      1728000         0

For setting offsets, both representations of clocks (numeric and symbolic)
can be used.

As for compatibility, it is acceptable to change things as long as
userspace doesn't care. The format of timens_offsets files is very new and
there are no userspace tools yet which rely on this format.

But three projects crun, util-linux and criu rely on the interface of
setting time offsets and this is why it's required to continue supporting
the numeric clock IDs on write.

Fixes: 04a8682a ("fs/proc: Introduce /proc/pid/timens_offsets")
Suggested-by: default avatarMichael Kerrisk <>
Signed-off-by: default avatarAndrei Vagin <>
Signed-off-by: default avatarThomas Gleixner <>
Tested-by: default avatarMichael Kerrisk <>
Acked-by: default avatarMichael Kerrisk <>
Cc: Andrew Morton <>
Cc: Eric W. Biederman <>
Cc: Dmitry Safonov <>
parent 8f3d9f35
......@@ -1573,6 +1573,7 @@ static ssize_t timens_offsets_write(struct file *file, const char __user *buf,
noffsets = 0;
for (pos = kbuf; pos; pos = next_line) {
struct proc_timens_offset *off = &offsets[noffsets];
char clock[10];
int err;
/* Find the end of line and ensure we don't look past it */
......@@ -1584,10 +1585,21 @@ static ssize_t timens_offsets_write(struct file *file, const char __user *buf,
next_line = NULL;
err = sscanf(pos, "%u %lld %lu", &off->clockid,
err = sscanf(pos, "%9s %lld %lu", clock,
&off->val.tv_sec, &off->val.tv_nsec);
if (err != 3 || off->val.tv_nsec >= NSEC_PER_SEC)
goto out;
clock[sizeof(clock) - 1] = 0;
if (strcmp(clock, "monotonic") == 0 ||
strcmp(clock, __stringify(CLOCK_MONOTONIC)) == 0)
off->clockid = CLOCK_MONOTONIC;
else if (strcmp(clock, "boottime") == 0 ||
strcmp(clock, __stringify(CLOCK_BOOTTIME)) == 0)
off->clockid = CLOCK_BOOTTIME;
goto out;
if (noffsets == ARRAY_SIZE(offsets)) {
if (next_line)
......@@ -338,7 +338,20 @@ static struct user_namespace *timens_owner(struct ns_common *ns)
static void show_offset(struct seq_file *m, int clockid, struct timespec64 *ts)
seq_printf(m, "%d %lld %ld\n", clockid, ts->tv_sec, ts->tv_nsec);
char *clock;
switch (clockid) {
clock = "boottime";
clock = "monotonic";
clock = "unknown";
seq_printf(m, "%-10s %10lld %9ld\n", clock, ts->tv_sec, ts->tv_nsec);
void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m)
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