Re: [PATCH] Use boot based time for process start time and boot time in /proc

[john stultz <johnstul@us.ibm.com>]

On Thu, 2007-05-10 at 19:10 +0200, Tomas Janousek wrote:
> Commit 411187fb05cd11676b0979d9fbf3291db69dbce2 caused boot time to move and
> process start times to become invalid after suspend. Using boot based time for
> those restores the old behaviour and fixes the issue.
> 
> Signed-off-by: Tomas Janousek <tjanouse@redhat.com>
> Cc: Tomas Smetana <tsmetana@redhat.com>
> Cc: John Stultz <johnstul@us.ibm.com>

Acked-by: John Stultz <johnstul@us.ibm.com>

> ---
>  fs/proc/array.c       |    5 +++--
>  fs/proc/proc_misc.c   |    8 +++++---
>  include/linux/sched.h |    2 +-
>  kernel/fork.c         |    2 ++
>  4 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/proc/array.c b/fs/proc/array.c
> index 74f30e0..e798e11 100644
> --- a/fs/proc/array.c
> +++ b/fs/proc/array.c
> @@ -405,8 +405,9 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
> 
>  	/* Temporary variable needed for gcc-2.96 */
>  	/* convert timespec -> nsec*/
> -	start_time = (unsigned long long)task->start_time.tv_sec * NSEC_PER_SEC
> -				+ task->start_time.tv_nsec;
> +	start_time =
> +		(unsigned long long)task->real_start_time.tv_sec * NSEC_PER_SEC
> +				+ task->real_start_time.tv_nsec;
>  	/* convert nsec -> ticks */
>  	start_time = nsec_to_clock_t(start_time);
> 
> diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
> index 4636be7..0782d34 100644
> --- a/fs/proc/proc_misc.c
> +++ b/fs/proc/proc_misc.c
> @@ -445,12 +445,14 @@ static int show_stat(struct seq_file *p, void *v)
>  	unsigned long jif;
>  	cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
>  	u64 sum = 0;
> +	struct timespec boottime;
> 
>  	user = nice = system = idle = iowait =
>  		irq = softirq = steal = cputime64_zero;
> -	jif = - wall_to_monotonic.tv_sec;
> -	if (wall_to_monotonic.tv_nsec)
> -		--jif;
> +	getboottime(&boottime);
> +	jif = boottime.tv_sec;
> +	if (boottime.tv_nsec)
> +		++jif;
> 
>  	for_each_possible_cpu(i) {
>  		int j;
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 40645b4..386ff51 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -918,7 +918,7 @@ struct task_struct {
>  	unsigned int rt_priority;
>  	cputime_t utime, stime;
>  	unsigned long nvcsw, nivcsw; /* context switch counts */
> -	struct timespec start_time;
> +	struct timespec start_time, real_start_time;
>  /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
>  	unsigned long min_flt, maj_flt;
> 
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 4239de2..3aa82bc 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1059,6 +1059,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
> 
>  	p->lock_depth = -1;		/* -1 = no lock */
>  	do_posix_clock_monotonic_gettime(&p->start_time);
> +	p->real_start_time = p->start_time;
> +	monotonic_to_bootbased(&p->real_start_time);
>  	p->security = NULL;
>  	p->io_context = NULL;
>  	p->io_wait = NULL;
> -- 
> 1.5.1.4
> 
>