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sched: Rework check_for_tasks() 

1) Iterate thru all of threads in the system.
   Check for all threads, not only for group leaders.

2) Check for p->on_rq instead of p->state and cputime.
   Preempted task in !TASK_RUNNING state  OR just
   created task may be queued, that we want to be
   reported too.

3) Use read_lock() instead of write_lock().
   This function does not change any structures, and
   read_lock() is enough.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Cc: Konstantin Khorenko <khorenko@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael wang <wangyun@linux.vnet.ibm.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul Turner <pjt@google.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Todd E Brandt <todd.e.brandt@linux.intel.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1403684395.3462.44.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Kirill Tkhai 2014-06-25 12:19:55 +04:00 committed by Ingo Molnar
parent 99b625670f
commit b728ca0602
1 changed files with 20 additions and 13 deletions
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33
kernel/cpu.c
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@ -274,21 +274,28 @@ void clear_tasks_mm_cpumask(int cpu)
rcu_read_unlock(); rcu_read_unlock();
} }
static inline void check_for_tasks(int cpu) static inline void check_for_tasks(int dead_cpu)
{ {
struct task_struct *p; struct task_struct *g, *p;
cputime_t utime, stime;
write_lock_irq(&tasklist_lock); read_lock_irq(&tasklist_lock);
for_each_process(p) { do_each_thread(g, p) {
task_cputime(p, &utime, &stime); if (!p->on_rq)
if (task_cpu(p) == cpu && p->state == TASK_RUNNING && continue;
(utime || stime)) /*
pr_warn("Task %s (pid = %d) is on cpu %d (state = %ld, flags = %x)\n", * We do the check with unlocked task_rq(p)->lock.
p->comm, task_pid_nr(p), cpu, * Order the reading to do not warn about a task,
p->state, p->flags); * which was running on this cpu in the past, and
} * it's just been woken on another cpu.
write_unlock_irq(&tasklist_lock); */
rmb();
if (task_cpu(p) != dead_cpu)
continue;
pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
} while_each_thread(g, p);
read_unlock_irq(&tasklist_lock);
} }
struct take_cpu_down_param { struct take_cpu_down_param {