Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ] 
  1 /*
  2  * kernel/cgroup_debug.c - Example cgroup subsystem that
  3  * exposes debug info
  4  *
  5  * Copyright (C) Google Inc, 2007
  6  *
  7  * Developed by Paul Menage (menage@google.com)
  8  *
  9  */
 10 
 11 #include <linux/cgroup.h>
 12 #include <linux/fs.h>
 13 #include <linux/slab.h>
 14 #include <linux/rcupdate.h>
 15 
 16 #include <asm/atomic.h>
 17 
 18 static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
 19                                                    struct cgroup *cont)
 20 {
 21         struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
 22 
 23         if (!css)
 24                 return ERR_PTR(-ENOMEM);
 25 
 26         return css;
 27 }
 28 
 29 static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
 30 {
 31         kfree(cont->subsys[debug_subsys_id]);
 32 }
 33 
 34 static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
 35 {
 36         return atomic_read(&cont->count);
 37 }
 38 
 39 static u64 taskcount_read(struct cgroup *cont, struct cftype *cft)
 40 {
 41         u64 count;
 42 
 43         count = cgroup_task_count(cont);
 44         return count;
 45 }
 46 
 47 static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
 48 {
 49         return (u64)(long)current->cgroups;
 50 }
 51 
 52 static u64 current_css_set_refcount_read(struct cgroup *cont,
 53                                            struct cftype *cft)
 54 {
 55         u64 count;
 56 
 57         rcu_read_lock();
 58         count = atomic_read(&current->cgroups->refcount);
 59         rcu_read_unlock();
 60         return count;
 61 }
 62 
 63 static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
 64 {
 65         return test_bit(CGRP_RELEASABLE, &cgrp->flags);
 66 }
 67 
 68 static struct cftype files[] =  {
 69         {
 70                 .name = "cgroup_refcount",
 71                 .read_u64 = cgroup_refcount_read,
 72         },
 73         {
 74                 .name = "taskcount",
 75                 .read_u64 = taskcount_read,
 76         },
 77 
 78         {
 79                 .name = "current_css_set",
 80                 .read_u64 = current_css_set_read,
 81         },
 82 
 83         {
 84                 .name = "current_css_set_refcount",
 85                 .read_u64 = current_css_set_refcount_read,
 86         },
 87 
 88         {
 89                 .name = "releasable",
 90                 .read_u64 = releasable_read,
 91         },
 92 };
 93 
 94 static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
 95 {
 96         return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
 97 }
 98 
 99 struct cgroup_subsys debug_subsys = {
100         .name = "debug",
101         .create = debug_create,
102         .destroy = debug_destroy,
103         .populate = debug_populate,
104         .subsys_id = debug_subsys_id,
105 };
106
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