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timerfd: Implement show_fdinfo method

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For checkpoint/restore of timerfd files we need to know how exactly
the timer were armed, to be able to recreate it on restore stage.
Thus implement show_fdinfo method which provides enough information
for that.

One of significant changes I think is the addition of @settime_flags
member. Currently there are two flags TFD_TIMER_ABSTIME and
TFD_TIMER_CANCEL_ON_SET, and the second can be found from
@might_cancel variable but in case if the flags will be extended
in future we most probably will have to somehow remember them
explicitly anyway so I guss doing that right now won't hurt.

To not bloat the timerfd_ctx structure I've converted @expired
to short integer and defined @settime_flags as short too.

v2 (by avagin@, vdavydov@ and tglx@):

 - Add it_value/it_interval fields
 - Save flags being used in timerfd_setup in context

v3 (by tglx@):
 - don't forget to use CONFIG_PROC_FS

v4 (by akpm@):
 -Use define timerfd_show NULL for non c/r config

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Link: http://lkml.kernel.org/r/20140715215703.114365649@openvz.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Cyrill Gorcunov 2014-07-16 01:54:52 +04:00 committed by Thomas Gleixner
parent afdb094380
commit af9c4957cf
1 changed files with 33 additions and 1 deletions
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34
fs/timerfd.c
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@ -35,8 +35,9 @@ struct timerfd_ctx {
ktime_t moffs;
wait_queue_head_t wqh;
u64 ticks;
int expired;
int clockid;
short unsigned expired;
short unsigned settime_flags; /* to show in fdinfo */
struct rcu_head rcu;
struct list_head clist;
bool might_cancel;
@ -196,6 +197,8 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
if (timerfd_canceled(ctx))
return -ECANCELED;
}
ctx->settime_flags = flags & TFD_SETTIME_FLAGS;
return 0;
}
@ -284,11 +287,40 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
return res;
}
#ifdef CONFIG_PROC_FS
static int timerfd_show(struct seq_file *m, struct file *file)
{
struct timerfd_ctx *ctx = file->private_data;
struct itimerspec t;
spin_lock_irq(&ctx->wqh.lock);
t.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
t.it_interval = ktime_to_timespec(ctx->tintv);
spin_unlock_irq(&ctx->wqh.lock);
return seq_printf(m,
"clockid: %d\n"
"ticks: %llu\n"
"settime flags: 0%o\n"
"it_value: (%llu, %llu)\n"
"it_interval: (%llu, %llu)\n",
ctx->clockid, (unsigned long long)ctx->ticks,
ctx->settime_flags,
(unsigned long long)t.it_value.tv_sec,
(unsigned long long)t.it_value.tv_nsec,
(unsigned long long)t.it_interval.tv_sec,
(unsigned long long)t.it_interval.tv_nsec);
}
#else
#define timerfd_show NULL
#endif
static const struct file_operations timerfd_fops = {
.release = timerfd_release,
.poll = timerfd_poll,
.read = timerfd_read,
.llseek = noop_llseek,
.show_fdinfo = timerfd_show,
};
static int timerfd_fget(int fd, struct fd *p)