mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-11 12:28:41 +08:00
cgroup: remove css_scan_tasks()
css_scan_tasks() doesn't have any user left. Remove it. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo
parent
d66393e54e
commit
889ed9ceaa
@ -14,7 +14,6 @@
|
||||
#include <linux/rcupdate.h>
|
||||
#include <linux/rculist.h>
|
||||
#include <linux/cgroupstats.h>
|
||||
#include <linux/prio_heap.h>
|
||||
#include <linux/rwsem.h>
|
||||
#include <linux/idr.h>
|
||||
#include <linux/workqueue.h>
|
||||
@ -813,11 +812,6 @@ void css_task_iter_start(struct cgroup_subsys_state *css,
|
||||
struct task_struct *css_task_iter_next(struct css_task_iter *it);
|
||||
void css_task_iter_end(struct css_task_iter *it);
|
||||
|
||||
int css_scan_tasks(struct cgroup_subsys_state *css,
|
||||
bool (*test)(struct task_struct *, void *),
|
||||
void (*process)(struct task_struct *, void *),
|
||||
void *data, struct ptr_heap *heap);
|
||||
|
||||
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
|
||||
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
|
||||
|
||||
|
||||
162
kernel/cgroup.c
162
kernel/cgroup.c
@ -2697,168 +2697,6 @@ void css_task_iter_end(struct css_task_iter *it)
|
||||
up_read(&css_set_rwsem);
|
||||
}
|
||||
|
||||
static inline int started_after_time(struct task_struct *t1,
|
||||
struct timespec *time,
|
||||
struct task_struct *t2)
|
||||
{
|
||||
int start_diff = timespec_compare(&t1->start_time, time);
|
||||
if (start_diff > 0) {
|
||||
return 1;
|
||||
} else if (start_diff < 0) {
|
||||
return 0;
|
||||
} else {
|
||||
/*
|
||||
* Arbitrarily, if two processes started at the same
|
||||
* time, we'll say that the lower pointer value
|
||||
* started first. Note that t2 may have exited by now
|
||||
* so this may not be a valid pointer any longer, but
|
||||
* that's fine - it still serves to distinguish
|
||||
* between two tasks started (effectively) simultaneously.
|
||||
*/
|
||||
return t1 > t2;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* This function is a callback from heap_insert() and is used to order
|
||||
* the heap.
|
||||
* In this case we order the heap in descending task start time.
|
||||
*/
|
||||
static inline int started_after(void *p1, void *p2)
|
||||
{
|
||||
struct task_struct *t1 = p1;
|
||||
struct task_struct *t2 = p2;
|
||||
return started_after_time(t1, &t2->start_time, t2);
|
||||
}
|
||||
|
||||
/**
|
||||
* css_scan_tasks - iterate though all the tasks in a css
|
||||
* @css: the css to iterate tasks of
|
||||
* @test: optional test callback
|
||||
* @process: process callback
|
||||
* @data: data passed to @test and @process
|
||||
* @heap: optional pre-allocated heap used for task iteration
|
||||
*
|
||||
* Iterate through all the tasks in @css, calling @test for each, and if it
|
||||
* returns %true, call @process for it also.
|
||||
*
|
||||
* @test may be NULL, meaning always true (select all tasks), which
|
||||
* effectively duplicates css_task_iter_{start,next,end}() but does not
|
||||
* lock css_set_rwsem for the call to @process.
|
||||
*
|
||||
* It is guaranteed that @process will act on every task that is a member
|
||||
* of @css for the duration of this call. This function may or may not
|
||||
* call @process for tasks that exit or move to a different css during the
|
||||
* call, or are forked or move into the css during the call.
|
||||
*
|
||||
* Note that @test may be called with locks held, and may in some
|
||||
* situations be called multiple times for the same task, so it should be
|
||||
* cheap.
|
||||
*
|
||||
* If @heap is non-NULL, a heap has been pre-allocated and will be used for
|
||||
* heap operations (and its "gt" member will be overwritten), else a
|
||||
* temporary heap will be used (allocation of which may cause this function
|
||||
* to fail).
|
||||
*/
|
||||
int css_scan_tasks(struct cgroup_subsys_state *css,
|
||||
bool (*test)(struct task_struct *, void *),
|
||||
void (*process)(struct task_struct *, void *),
|
||||
void *data, struct ptr_heap *heap)
|
||||
{
|
||||
int retval, i;
|
||||
struct css_task_iter it;
|
||||
struct task_struct *p, *dropped;
|
||||
/* Never dereference latest_task, since it's not refcounted */
|
||||
struct task_struct *latest_task = NULL;
|
||||
struct ptr_heap tmp_heap;
|
||||
struct timespec latest_time = { 0, 0 };
|
||||
|
||||
if (heap) {
|
||||
/* The caller supplied our heap and pre-allocated its memory */
|
||||
heap->gt = &started_after;
|
||||
} else {
|
||||
/* We need to allocate our own heap memory */
|
||||
heap = &tmp_heap;
|
||||
retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
|
||||
if (retval)
|
||||
/* cannot allocate the heap */
|
||||
return retval;
|
||||
}
|
||||
|
||||
again:
|
||||
/*
|
||||
* Scan tasks in the css, using the @test callback to determine
|
||||
* which are of interest, and invoking @process callback on the
|
||||
* ones which need an update. Since we don't want to hold any
|
||||
* locks during the task updates, gather tasks to be processed in a
|
||||
* heap structure. The heap is sorted by descending task start
|
||||
* time. If the statically-sized heap fills up, we overflow tasks
|
||||
* that started later, and in future iterations only consider tasks
|
||||
* that started after the latest task in the previous pass. This
|
||||
* guarantees forward progress and that we don't miss any tasks.
|
||||
*/
|
||||
heap->size = 0;
|
||||
css_task_iter_start(css, &it);
|
||||
while ((p = css_task_iter_next(&it))) {
|
||||
/*
|
||||
* Only affect tasks that qualify per the caller's callback,
|
||||
* if he provided one
|
||||
*/
|
||||
if (test && !test(p, data))
|
||||
continue;
|
||||
/*
|
||||
* Only process tasks that started after the last task
|
||||
* we processed
|
||||
*/
|
||||
if (!started_after_time(p, &latest_time, latest_task))
|
||||
continue;
|
||||
dropped = heap_insert(heap, p);
|
||||
if (dropped == NULL) {
|
||||
/*
|
||||
* The new task was inserted; the heap wasn't
|
||||
* previously full
|
||||
*/
|
||||
get_task_struct(p);
|
||||
} else if (dropped != p) {
|
||||
/*
|
||||
* The new task was inserted, and pushed out a
|
||||
* different task
|
||||
*/
|
||||
get_task_struct(p);
|
||||
put_task_struct(dropped);
|
||||
}
|
||||
/*
|
||||
* Else the new task was newer than anything already in
|
||||
* the heap and wasn't inserted
|
||||
*/
|
||||
}
|
||||
css_task_iter_end(&it);
|
||||
|
||||
if (heap->size) {
|
||||
for (i = 0; i < heap->size; i++) {
|
||||
struct task_struct *q = heap->ptrs[i];
|
||||
if (i == 0) {
|
||||
latest_time = q->start_time;
|
||||
latest_task = q;
|
||||
}
|
||||
/* Process the task per the caller's callback */
|
||||
process(q, data);
|
||||
put_task_struct(q);
|
||||
}
|
||||
/*
|
||||
* If we had to process any tasks at all, scan again
|
||||
* in case some of them were in the middle of forking
|
||||
* children that didn't get processed.
|
||||
* Not the most efficient way to do it, but it avoids
|
||||
* having to take callback_mutex in the fork path
|
||||
*/
|
||||
goto again;
|
||||
}
|
||||
if (heap == &tmp_heap)
|
||||
heap_free(&tmp_heap);
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* cgroup_trasnsfer_tasks - move tasks from one cgroup to another
|
||||
* @to: cgroup to which the tasks will be moved
|
||||
|
||||
Loading…
Reference in New Issue
Block a user