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    Subject[tip:sched/core] sched/debug: Intruduce task_state_to_char() helper function
    Commit-ID:  20435d84e5f2041c64c792399ab6f2948a2c2252
    Gitweb: http://git.kernel.org/tip/20435d84e5f2041c64c792399ab6f2948a2c2252
    Author: Xie XiuQi <xiexiuqi@huawei.com>
    AuthorDate: Mon, 7 Aug 2017 16:44:23 +0800
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Thu, 10 Aug 2017 12:18:20 +0200

    sched/debug: Intruduce task_state_to_char() helper function

    Now that we have more than one place to get the task state,
    intruduce the task_state_to_char() helper function to save some code.

    No functionality changed.

    Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Cc: <cj.chengjian@huawei.com>
    Cc: <huawei.libin@huawei.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/1502095463-160172-3-git-send-email-xiexiuqi@huawei.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    include/linux/sched.h | 13 +++++++++++++
    kernel/sched/core.c | 15 ++++-----------
    kernel/sched/debug.c | 10 +++-------
    3 files changed, 20 insertions(+), 18 deletions(-)

    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index 8337e2d..c28b182 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -1229,6 +1229,19 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk)
    return task_pgrp_nr_ns(tsk, &init_pid_ns);
    }

    +static inline char task_state_to_char(struct task_struct *task)
    +{
    + const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
    + unsigned long state = task->state;
    +
    + state = state ? __ffs(state) + 1 : 0;
    +
    + /* Make sure the string lines up properly with the number of task states: */
    + BUILD_BUG_ON(sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1);
    +
    + return state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?';
    +}
    +
    /**
    * is_global_init - check if a task structure is init. Since init
    * is free to have sub-threads we need to check tgid.
    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index 6d91c10..f9f9948 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -5103,24 +5103,17 @@ out_unlock:
    return retval;
    }

    -static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
    -
    void sched_show_task(struct task_struct *p)
    {
    unsigned long free = 0;
    int ppid;
    - unsigned long state = p->state;
    -
    - /* Make sure the string lines up properly with the number of task states: */
    - BUILD_BUG_ON(sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1);

    if (!try_get_task_stack(p))
    return;
    - if (state)
    - state = __ffs(state) + 1;
    - printk(KERN_INFO "%-15.15s %c", p->comm,
    - state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
    - if (state == TASK_RUNNING)
    +
    + printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p));
    +
    + if (p->state == TASK_RUNNING)
    printk(KERN_CONT " running task ");
    #ifdef CONFIG_DEBUG_STACK_USAGE
    free = stack_not_used(p);
    diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
    index d8d2ea2..cfd84f7 100644
    --- a/kernel/sched/debug.c
    +++ b/kernel/sched/debug.c
    @@ -426,14 +426,10 @@ static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
    static void
    print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
    {
    - unsigned long state;
    -
    - if (rq->curr == p) {
    + if (rq->curr == p)
    SEQ_printf(m, ">R");
    - } else {
    - state = p->state ? __ffs(p->state) + 1 : 0;
    - SEQ_printf(m, " %c", state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
    - }
    + else
    + SEQ_printf(m, " %c", task_state_to_char(p));

    SEQ_printf(m, "%15s %5d %9Ld.%06ld %9Ld %5d ",
    p->comm, task_pid_nr(p),
    \
     
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