Commit-ID: b728ca06029d085a1585c1926610f26de93b9146 Gitweb: http://git.kernel.org/tip/b728ca06029d085a1585c1926610f26de93b9146 Author: Kirill Tkhai <[email protected]> AuthorDate: Wed, 25 Jun 2014 12:19:55 +0400 Committer: Ingo Molnar <[email protected]> CommitDate: Sat, 5 Jul 2014 11:17:45 +0200
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 <[email protected]> Reviewed-by: Srikar Dronamraju <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Ben Segall <[email protected]> Cc: Fabian Frederick <[email protected]> Cc: Gautham R. Shenoy <[email protected]> Cc: Konstantin Khorenko <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Michael wang <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Paul Gortmaker <[email protected]> Cc: Paul Turner <[email protected]> Cc: Rafael J. Wysocki <[email protected]> Cc: Srivatsa S. Bhat <[email protected]> Cc: Todd E Brandt <[email protected]> Cc: Toshi Kani <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/1403684395.3462.44.camel@tkhai Signed-off-by: Ingo Molnar <[email protected]> --- kernel/cpu.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index a343bde..81e2a38 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -274,21 +274,28 @@ void clear_tasks_mm_cpumask(int cpu) rcu_read_unlock(); } -static inline void check_for_tasks(int cpu) +static inline void check_for_tasks(int dead_cpu) { - struct task_struct *p; - cputime_t utime, stime; + struct task_struct *g, *p; - write_lock_irq(&tasklist_lock); - for_each_process(p) { - task_cputime(p, &utime, &stime); - if (task_cpu(p) == cpu && p->state == TASK_RUNNING && - (utime || stime)) - pr_warn("Task %s (pid = %d) is on cpu %d (state = %ld, flags = %x)\n", - p->comm, task_pid_nr(p), cpu, - p->state, p->flags); - } - write_unlock_irq(&tasklist_lock); + read_lock_irq(&tasklist_lock); + do_each_thread(g, p) { + if (!p->on_rq) + continue; + /* + * We do the check with unlocked task_rq(p)->lock. + * Order the reading to do not warn about a task, + * which was running on this cpu in the past, and + * it's just been woken on another cpu. + */ + 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 { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
