Re: [PATCHv3 03/27] timens: Introduce CLOCK_MONOTONIC offsets
flat view
From: Thomas Gleixner <hidden>
Date: 2019-04-25 19:53:06
Also in:
lkml
On Thu, 25 Apr 2019, Dmitry Safonov wrote:
From: Andrei Vagin <redacted> Add monotonic time virtualisation for time namespace. Introduce timespec for monotionic clock into timens offsets and wire clock_gettime() syscall.
That's a bit meager. It should at least explain the concept how this is supposed to work.
#define CLOCKS_MASK (CLOCK_REALTIME | CLOCK_MONOTONIC) #define CLOCKS_MONO CLOCK_MONOTONIC
Unrelated to this, but those two defines can go away.
+#define CLOCK_TIMENS 1024
Random number pulled out of thin air without any explanation. Aside of that why is this exposed to user space?
quoted hunk ↗ jump to hunk
@@ -77,6 +78,7 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp) break; case CLOCK_MONOTONIC: ktime_get_ts64(tp); + timens_add_monotonic(tp); break; case CLOCK_BOOTTIME: ktime_get_boottime_ts64(tp);diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index 29176635991f..a047d6b7c768 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c@@ -30,6 +30,7 @@ #include <linux/hashtable.h> #include <linux/compat.h> #include <linux/nospec.h> +#include <linux/time_namespace.h> #include "timekeeping.h" #include "posix-timers.h"@@ -190,6 +191,8 @@ static int posix_clock_realtime_adj(const clockid_t which_clock, static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp) { ktime_get_ts64(tp); + if (which_clock & CLOCK_TIMENS) + timens_add_monotonic(tp);
quoted hunk ↗ jump to hunk
@@ -1039,7 +1046,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock, if (!kc) return -EINVAL; - error = kc->clock_get(which_clock, &kernel_tp); + error = kc->clock_get(which_clock | CLOCK_TIMENS, &kernel_tp);
Bah. After some banging the head against the wall I figured out what you
are doing here. It's because kc->clock_get() is used in common_timer_get()
as well and there you don't want the adjustment there. Sorry, but this is
uncomprehensible and unmaintainable and adds yet another conditional into
the code flow.
The callsite in common_timer_get() has already a comment:
/*
* The timespec64 based conversion is suboptimal, but it's not
* worth to implement yet another callback.
*/
kc->clock_get(timr->it_clock, &ts64);
now = timespec64_to_ktime(ts64);
So now we have a proper justification to add that extra callback:
separation of functionality. It's trivial and not a massive code size
overhead.
Thanks,
tglx