| Date | Mon, 13 Jan 2020 19:09:29 -0000 | From | "tip-bot2 for Andrei Vagin" <> | Subject | [tip: timers/core] time: Add do_timens_ktime_to_host() helper |
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The following commit has been merged into the timers/core branch of tip:
Commit-ID: 6c9c1492c9fd0732dfa85c9cb55f71f2571c3825 Gitweb: https://git.kernel.org/tip/6c9c1492c9fd0732dfa85c9cb55f71f2571c3825 Author: Andrei Vagin <avagin@gmail.com> AuthorDate: Tue, 12 Nov 2019 01:27:01 Committer: Thomas Gleixner <tglx@linutronix.de> CommitterDate: Mon, 13 Jan 2020 08:10:51 +01:00
time: Add do_timens_ktime_to_host() helper
The helper subtracts namespace's clock offset from the given time and ensures that the result is within [0, KTIME_MAX].
Co-developed-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20191112012724.250792-13-dima@arista.com
--- include/linux/time_namespace.h | 17 ++++++++++++++++- kernel/time/namespace.c | 36 +++++++++++++++++++++++++++++++++- 2 files changed, 53 insertions(+)
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h index d7e3b49..34ee110 100644 --- a/include/linux/time_namespace.h +++ b/include/linux/time_namespace.h @@ -59,6 +59,19 @@ static inline void timens_add_boottime(struct timespec64 *ts) *ts = timespec64_add(*ts, ns_offsets->boottime); } +ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim, + struct timens_offsets *offsets); + +static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim) +{ + struct time_namespace *ns = current->nsproxy->time_ns; + + if (likely(ns == &init_time_ns)) + return tim; + + return do_timens_ktime_to_host(clockid, tim, &ns->offsets); +} + #else static inline struct time_namespace *get_time_ns(struct time_namespace *ns) { @@ -88,6 +101,10 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, static inline void timens_add_monotonic(struct timespec64 *ts) { } static inline void timens_add_boottime(struct timespec64 *ts) { } +static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim) +{ + return tim; +} #endif #endif /* _LINUX_TIMENS_H */ diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c index c2a58e4..1a0fbaa 100644 --- a/kernel/time/namespace.c +++ b/kernel/time/namespace.c @@ -16,6 +16,42 @@ #include <linux/err.h> #include <linux/mm.h> +ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim, + struct timens_offsets *ns_offsets) +{ + ktime_t offset; + + switch (clockid) { + case CLOCK_MONOTONIC: + offset = timespec64_to_ktime(ns_offsets->monotonic); + break; + case CLOCK_BOOTTIME: + case CLOCK_BOOTTIME_ALARM: + offset = timespec64_to_ktime(ns_offsets->boottime); + break; + default: + return tim; + } + + /* + * Check that @tim value is in [offset, KTIME_MAX + offset] + * and subtract offset. + */ + if (tim < offset) { + /* + * User can specify @tim *absolute* value - if it's lesser than + * the time namespace's offset - it's already expired. + */ + tim = 0; + } else { + tim = ktime_sub(tim, offset); + if (unlikely(tim > KTIME_MAX)) + tim = KTIME_MAX; + } + + return tim; +} + static struct ucounts *inc_time_namespaces(struct user_namespace *ns) { return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);
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