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cgroup: remove css_scan_tasks()

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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 2014-02-13 06:58:40 -05:00
parent d66393e54e
commit 889ed9ceaa
2 changed files with 0 additions and 168 deletions
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6
include/linux/cgroup.h
View File

@ -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
View File

@ -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