Function _callout_stop_safe

lib/ff_kern_timeout.c:791–1009

}

int
_callout_stop_safe(struct callout *c, int flags, void (*drain)(void *))
{
    struct callout_cpu *cc, *old_cc;
    struct lock_class *class;
    int direct, sq_locked, use_lock;
    int cancelled, not_on_a_list;

    if ((flags & CS_DRAIN) != 0)
        WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
            "calling %s", __func__);

    /*
     * Some old subsystems don't hold Giant while running a callout_stop(),
     * so just discard this check for the moment.
     */
    if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) {
        if (c->c_lock == &Giant.lock_object)
            use_lock = mtx_owned(&Giant);
        else {
            use_lock = 1;
            class = LOCK_CLASS(c->c_lock);
            class->lc_assert(c->c_lock, LA_XLOCKED);
        }
    } else
        use_lock = 0;
    if (c->c_iflags & CALLOUT_DIRECT) {
        direct = 1;
    } else {
        direct = 0;
    }
    sq_locked = 0;
    old_cc = NULL;
again:
    cc = callout_lock(c);

    if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) ==
        (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) &&
        ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) {
        /*
         * Special case where this slipped in while we
         * were migrating *as* the callout is about to
         * execute. The caller probably holds the lock
         * the callout wants.
         *
         * Get rid of the migration first. Then set
         * the flag that tells this code *not* to
         * try to remove it from any lists (its not
         * on one yet). When the callout wheel runs,
         * it will ignore this callout.
         */
        c->c_iflags &= ~CALLOUT_PENDING;
        c->c_flags &= ~CALLOUT_ACTIVE;
        not_on_a_list = 1;
    } else {
        not_on_a_list = 0;
    }