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Date: Mon, 5 Sep 2016 11:13:02 +0200
From: Stanislaw Gruszka <sgruszka@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Giovanni Gherdovich <ggherdovich@...e.cz>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Mel Gorman <mgorman@...hsingularity.net>,
Mike Galbraith <mgalbraith@...e.de>,
Paolo Bonzini <pbonzini@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Rik van Riel <riel@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Wanpeng Li <wanpeng.li@...mail.com>,
Ingo Molnar <mingo@...nel.org>,
Stanislaw Gruszka <sgruszka@...hat.com>
Subject: [PATCH v2 2/2] sched/cputime: Protect other sum_exec_runtime reads on 32 bit cpus
We protect 64bit sum_exec_runtime variable against inconsistency on
32 bit architectures when reading it on thread_group_cputime(), but we
also read it on other places not protected.
Patch changes that, except file kernel/sched/debug.c , where we also
read some other u64 variables (vruntime, exec_start) without protection.
But since this is for debug purpose and inconsistency is very unlike,
we can ignore that.
Signed-off-by: Stanislaw Gruszka <sgruszka@...hat.com>
---
fs/proc/base.c | 2 +-
include/linux/sched.h | 19 +++++++++++++++++++
kernel/delayacct.c | 2 +-
kernel/exit.c | 2 +-
kernel/sched/cputime.c | 21 +--------------------
kernel/time/posix-cpu-timers.c | 4 ++--
6 files changed, 25 insertions(+), 25 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index e9ff186..8118d97 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -505,7 +505,7 @@ static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
seq_printf(m, "0 0 0\n");
else
seq_printf(m, "%llu %llu %lu\n",
- (unsigned long long)task->se.sum_exec_runtime,
+ (unsigned long long)read_sum_exec_runtime(task),
(unsigned long long)task->sched_info.run_delay,
task->sched_info.pcount);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index eb64fcd..267fc98 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2508,6 +2508,25 @@ static inline void disable_sched_clock_irqtime(void) {}
extern unsigned long long
task_sched_runtime(struct task_struct *task);
+#ifdef CONFIG_64BIT
+static inline u64 read_sum_exec_runtime(struct task_struct *t)
+{
+ return t->se.sum_exec_runtime;
+}
+#else
+static inline u64 read_sum_exec_runtime(struct task_struct *t)
+{
+ u64 ns;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&t->pi_lock, flags);
+ ns = t->se.sum_exec_runtime;
+ raw_spin_unlock_irqrestore(&t->pi_lock, flags);
+
+ return ns;
+}
+#endif
+
/* sched_exec is called by processes performing an exec */
#ifdef CONFIG_SMP
extern void sched_exec(void);
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index 435c14a..023b2ca 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -104,7 +104,7 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
*/
t1 = tsk->sched_info.pcount;
t2 = tsk->sched_info.run_delay;
- t3 = tsk->se.sum_exec_runtime;
+ t3 = read_sum_exec_runtime(tsk);
d->cpu_count += t1;
diff --git a/kernel/exit.c b/kernel/exit.c
index 2f974ae..a46f96f 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -134,7 +134,7 @@ static void __exit_signal(struct task_struct *tsk)
sig->inblock += task_io_get_inblock(tsk);
sig->oublock += task_io_get_oublock(tsk);
task_io_accounting_add(&sig->ioac, &tsk->ioac);
- sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
+ sig->sum_sched_runtime += read_sum_exec_runtime(tsk);
sig->nr_threads--;
__unhash_process(tsk, group_dead);
write_sequnlock(&sig->stats_lock);
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 5535774..4d080f2 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -306,25 +306,6 @@ static inline cputime_t account_other_time(cputime_t max)
return accounted;
}
-#ifdef CONFIG_64BIT
-static inline u64 read_sum_exec_runtime(struct task_struct *t)
-{
- return t->se.sum_exec_runtime;
-}
-#else
-static u64 read_sum_exec_runtime(struct task_struct *t)
-{
- u64 ns;
- unsigned long flags;
-
- raw_spin_lock_irqsave(&t->pi_lock, flags);
- ns = t->se.sum_exec_runtime;
- raw_spin_unlock_irqrestore(&t->pi_lock, flags);
-
- return ns;
-}
-#endif
-
/*
* Accumulate raw cputime values of dead tasks (sig->[us]time) and live
* tasks (sum on group iteration) belonging to @tsk's group.
@@ -701,7 +682,7 @@ out:
void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
struct task_cputime cputime = {
- .sum_exec_runtime = p->se.sum_exec_runtime,
+ .sum_exec_runtime = read_sum_exec_runtime(p),
};
task_cputime(p, &cputime.utime, &cputime.stime);
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 39008d7..a2d753b 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -848,7 +848,7 @@ static void check_thread_timers(struct task_struct *tsk,
tsk_expires->virt_exp = expires_to_cputime(expires);
tsk_expires->sched_exp = check_timers_list(++timers, firing,
- tsk->se.sum_exec_runtime);
+ read_sum_exec_runtime(tsk));
/*
* Check for the special case thread timers.
@@ -1115,7 +1115,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
struct task_cputime task_sample;
task_cputime(tsk, &task_sample.utime, &task_sample.stime);
- task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
+ task_sample.sum_exec_runtime = read_sum_exec_runtime(tsk);
if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
return 1;
}
--
1.8.3.1
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