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295 lines
6.6 KiB
295 lines
6.6 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* A simple wrapper around refcount. An allocated sched_core_cookie's |
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* address is used to compute the cookie of the task. |
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*/ |
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struct sched_core_cookie { |
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refcount_t refcnt; |
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}; |
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static unsigned long sched_core_alloc_cookie(void) |
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{ |
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struct sched_core_cookie *ck = kmalloc(sizeof(*ck), GFP_KERNEL); |
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if (!ck) |
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return 0; |
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refcount_set(&ck->refcnt, 1); |
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sched_core_get(); |
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return (unsigned long)ck; |
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} |
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static void sched_core_put_cookie(unsigned long cookie) |
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{ |
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struct sched_core_cookie *ptr = (void *)cookie; |
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if (ptr && refcount_dec_and_test(&ptr->refcnt)) { |
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kfree(ptr); |
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sched_core_put(); |
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} |
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} |
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static unsigned long sched_core_get_cookie(unsigned long cookie) |
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{ |
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struct sched_core_cookie *ptr = (void *)cookie; |
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if (ptr) |
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refcount_inc(&ptr->refcnt); |
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return cookie; |
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} |
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/* |
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* sched_core_update_cookie - replace the cookie on a task |
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* @p: the task to update |
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* @cookie: the new cookie |
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* |
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* Effectively exchange the task cookie; caller is responsible for lifetimes on |
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* both ends. |
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* |
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* Returns: the old cookie |
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*/ |
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static unsigned long sched_core_update_cookie(struct task_struct *p, |
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unsigned long cookie) |
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{ |
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unsigned long old_cookie; |
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struct rq_flags rf; |
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struct rq *rq; |
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bool enqueued; |
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rq = task_rq_lock(p, &rf); |
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/* |
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* Since creating a cookie implies sched_core_get(), and we cannot set |
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* a cookie until after we've created it, similarly, we cannot destroy |
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* a cookie until after we've removed it, we must have core scheduling |
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* enabled here. |
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*/ |
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SCHED_WARN_ON((p->core_cookie || cookie) && !sched_core_enabled(rq)); |
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enqueued = sched_core_enqueued(p); |
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if (enqueued) |
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sched_core_dequeue(rq, p, DEQUEUE_SAVE); |
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old_cookie = p->core_cookie; |
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p->core_cookie = cookie; |
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if (enqueued) |
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sched_core_enqueue(rq, p); |
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/* |
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* If task is currently running, it may not be compatible anymore after |
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* the cookie change, so enter the scheduler on its CPU to schedule it |
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* away. |
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* |
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* Note that it is possible that as a result of this cookie change, the |
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* core has now entered/left forced idle state. Defer accounting to the |
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* next scheduling edge, rather than always forcing a reschedule here. |
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*/ |
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if (task_running(rq, p)) |
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resched_curr(rq); |
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task_rq_unlock(rq, p, &rf); |
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return old_cookie; |
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} |
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static unsigned long sched_core_clone_cookie(struct task_struct *p) |
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{ |
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unsigned long cookie, flags; |
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raw_spin_lock_irqsave(&p->pi_lock, flags); |
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cookie = sched_core_get_cookie(p->core_cookie); |
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raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
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return cookie; |
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} |
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void sched_core_fork(struct task_struct *p) |
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{ |
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RB_CLEAR_NODE(&p->core_node); |
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p->core_cookie = sched_core_clone_cookie(current); |
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} |
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void sched_core_free(struct task_struct *p) |
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{ |
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sched_core_put_cookie(p->core_cookie); |
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} |
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static void __sched_core_set(struct task_struct *p, unsigned long cookie) |
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{ |
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cookie = sched_core_get_cookie(cookie); |
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cookie = sched_core_update_cookie(p, cookie); |
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sched_core_put_cookie(cookie); |
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} |
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/* Called from prctl interface: PR_SCHED_CORE */ |
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int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type, |
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unsigned long uaddr) |
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{ |
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unsigned long cookie = 0, id = 0; |
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struct task_struct *task, *p; |
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struct pid *grp; |
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int err = 0; |
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if (!static_branch_likely(&sched_smt_present)) |
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return -ENODEV; |
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BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_THREAD != PIDTYPE_PID); |
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BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_THREAD_GROUP != PIDTYPE_TGID); |
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BUILD_BUG_ON(PR_SCHED_CORE_SCOPE_PROCESS_GROUP != PIDTYPE_PGID); |
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if (type > PIDTYPE_PGID || cmd >= PR_SCHED_CORE_MAX || pid < 0 || |
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(cmd != PR_SCHED_CORE_GET && uaddr)) |
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return -EINVAL; |
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rcu_read_lock(); |
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if (pid == 0) { |
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task = current; |
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} else { |
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task = find_task_by_vpid(pid); |
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if (!task) { |
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rcu_read_unlock(); |
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return -ESRCH; |
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} |
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} |
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get_task_struct(task); |
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rcu_read_unlock(); |
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/* |
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* Check if this process has the right to modify the specified |
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* process. Use the regular "ptrace_may_access()" checks. |
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*/ |
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if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { |
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err = -EPERM; |
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goto out; |
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} |
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switch (cmd) { |
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case PR_SCHED_CORE_GET: |
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if (type != PIDTYPE_PID || uaddr & 7) { |
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err = -EINVAL; |
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goto out; |
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} |
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cookie = sched_core_clone_cookie(task); |
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if (cookie) { |
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/* XXX improve ? */ |
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ptr_to_hashval((void *)cookie, &id); |
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} |
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err = put_user(id, (u64 __user *)uaddr); |
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goto out; |
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case PR_SCHED_CORE_CREATE: |
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cookie = sched_core_alloc_cookie(); |
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if (!cookie) { |
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err = -ENOMEM; |
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goto out; |
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} |
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break; |
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case PR_SCHED_CORE_SHARE_TO: |
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cookie = sched_core_clone_cookie(current); |
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break; |
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case PR_SCHED_CORE_SHARE_FROM: |
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if (type != PIDTYPE_PID) { |
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err = -EINVAL; |
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goto out; |
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} |
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cookie = sched_core_clone_cookie(task); |
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__sched_core_set(current, cookie); |
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goto out; |
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default: |
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err = -EINVAL; |
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goto out; |
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}; |
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if (type == PIDTYPE_PID) { |
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__sched_core_set(task, cookie); |
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goto out; |
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} |
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read_lock(&tasklist_lock); |
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grp = task_pid_type(task, type); |
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do_each_pid_thread(grp, type, p) { |
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if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) { |
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err = -EPERM; |
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goto out_tasklist; |
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} |
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} while_each_pid_thread(grp, type, p); |
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do_each_pid_thread(grp, type, p) { |
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__sched_core_set(p, cookie); |
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} while_each_pid_thread(grp, type, p); |
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out_tasklist: |
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read_unlock(&tasklist_lock); |
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out: |
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sched_core_put_cookie(cookie); |
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put_task_struct(task); |
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return err; |
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} |
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#ifdef CONFIG_SCHEDSTATS |
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/* REQUIRES: rq->core's clock recently updated. */ |
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void __sched_core_account_forceidle(struct rq *rq) |
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{ |
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const struct cpumask *smt_mask = cpu_smt_mask(cpu_of(rq)); |
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u64 delta, now = rq_clock(rq->core); |
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struct rq *rq_i; |
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struct task_struct *p; |
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int i; |
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lockdep_assert_rq_held(rq); |
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WARN_ON_ONCE(!rq->core->core_forceidle_count); |
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if (rq->core->core_forceidle_start == 0) |
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return; |
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delta = now - rq->core->core_forceidle_start; |
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if (unlikely((s64)delta <= 0)) |
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return; |
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rq->core->core_forceidle_start = now; |
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if (WARN_ON_ONCE(!rq->core->core_forceidle_occupation)) { |
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/* can't be forced idle without a running task */ |
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} else if (rq->core->core_forceidle_count > 1 || |
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rq->core->core_forceidle_occupation > 1) { |
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/* |
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* For larger SMT configurations, we need to scale the charged |
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* forced idle amount since there can be more than one forced |
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* idle sibling and more than one running cookied task. |
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*/ |
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delta *= rq->core->core_forceidle_count; |
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delta = div_u64(delta, rq->core->core_forceidle_occupation); |
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} |
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for_each_cpu(i, smt_mask) { |
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rq_i = cpu_rq(i); |
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p = rq_i->core_pick ?: rq_i->curr; |
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if (p == rq_i->idle) |
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continue; |
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__schedstat_add(p->stats.core_forceidle_sum, delta); |
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} |
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} |
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void __sched_core_tick(struct rq *rq) |
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{ |
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if (!rq->core->core_forceidle_count) |
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return; |
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if (rq != rq->core) |
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update_rq_clock(rq->core); |
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__sched_core_account_forceidle(rq); |
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} |
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#endif /* CONFIG_SCHEDSTATS */
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