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

[Tomas Janousek <tjanouse@redhat.com>]

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>
---
 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


-- 
TJ. (Brno, CZ), BaseOS, Red Hat
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