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Commit af9c4957 authored by Cyrill Gorcunov's avatar Cyrill Gorcunov Committed by Thomas Gleixner
Browse files

timerfd: Implement show_fdinfo method 



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: default avatarCyrill 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent afdb0943

fs/timerfd.c

+33 −1
Original line number Diff line number Diff line
@@ -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)