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Subject[tip: timers/core] time: Add timens_offsets to be used for tasks in time namespace
The following commit has been merged into the timers/core branch of tip:

Commit-ID: af993f58d69ee9c1f421dfc87c3ed231c113989c
Gitweb: https://git.kernel.org/tip/af993f58d69ee9c1f421dfc87c3ed231c113989c
Author: Andrei Vagin <avagin@openvz.org>
AuthorDate: Tue, 12 Nov 2019 01:26:53
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 14 Jan 2020 12:20:49 +01:00

time: Add timens_offsets to be used for tasks in time namespace

Introduce offsets for time namespace. They will contain an adjustment
needed to convert clocks to/from host's.

A new namespace is created with the same offsets as the time namespace
of the current process.

Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-5-dima@arista.com


---
include/linux/time_namespace.h | 22 ++++++++++++++++++++++
kernel/time/namespace.c | 2 ++
2 files changed, 24 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 8c74cc1..d7e3b49 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -12,11 +12,17 @@
struct user_namespace;
extern struct user_namespace init_user_ns;

+struct timens_offsets {
+ struct timespec64 monotonic;
+ struct timespec64 boottime;
+};
+
struct time_namespace {
struct kref kref;
struct user_namespace *user_ns;
struct ucounts *ucounts;
struct ns_common ns;
+ struct timens_offsets offsets;
} __randomize_layout;

extern struct time_namespace init_time_ns;
@@ -39,6 +45,20 @@ static inline void put_time_ns(struct time_namespace *ns)
kref_put(&ns->kref, free_time_ns);
}

+static inline void timens_add_monotonic(struct timespec64 *ts)
+{
+ struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
+
+ *ts = timespec64_add(*ts, ns_offsets->monotonic);
+}
+
+static inline void timens_add_boottime(struct timespec64 *ts)
+{
+ struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
+
+ *ts = timespec64_add(*ts, ns_offsets->boottime);
+}
+
#else
static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
{
@@ -66,6 +86,8 @@ static inline int timens_on_fork(struct nsproxy *nsproxy,
return 0;
}

+static inline void timens_add_monotonic(struct timespec64 *ts) { }
+static inline void timens_add_boottime(struct timespec64 *ts) { }
#endif

#endif /* _LINUX_TIMENS_H */
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 2662a69..c2a58e4 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/err.h>
+#include <linux/mm.h>

static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
{
@@ -60,6 +61,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
ns->ucounts = ucounts;
ns->ns.ops = &timens_operations;
ns->user_ns = get_user_ns(user_ns);
+ ns->offsets = old_ns->offsets;
return ns;

fail_free:
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