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[PATCH] Define struct pspace

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Define a per-container pid space object.  And create one instance of this
object, init_pspace, to define the entire pid space.  Subsequent patches
will provide/use interfaces to create/destroy pid spaces.

Its a subset/rework of Eric Biederman's patch
http://lkml.org/lkml/2006/2/6/285 .

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Andrey Savochkin <saw@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Sukadev Bhattiprolu 2006-10-02 02:17:24 -07:00 committed by Linus Torvalds
parent aa5a6662f9
commit 3fbc964864
4 changed files with 40 additions and 24 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
fs/proc/proc_misc.c
View file

@ -45,6 +45,7 @@
#include <linux/sysrq.h>
#include <linux/vmalloc.h>
#include <linux/crash_dump.h>
#include <linux/pspace.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
@ -91,7 +92,7 @@ static int loadavg_read_proc(char *page, char **start, off_t off,
LOAD_INT(a), LOAD_FRAC(a),
LOAD_INT(b), LOAD_FRAC(b),
LOAD_INT(c), LOAD_FRAC(c),
nr_running(), nr_threads, last_pid);
nr_running(), nr_threads, init_pspace.last_pid);
return proc_calc_metrics(page, start, off, count, eof, len);
}

7
include/linux/pspace.h
View file

@ -13,4 +13,11 @@ struct pidmap {
#define PIDMAP_ENTRIES ((PID_MAX_LIMIT + 8*PAGE_SIZE - 1)/PAGE_SIZE/8)
struct pspace {
struct pidmap pidmap[PIDMAP_ENTRIES];
int last_pid;
};
extern struct pspace init_pspace;
#endif /* _LINUX_PSPACE_H */

1
include/linux/sched.h
View file

@ -118,7 +118,6 @@ extern unsigned long avenrun[]; /* Load averages */
extern unsigned long total_forks;
extern int nr_threads;
extern int last_pid;
DECLARE_PER_CPU(unsigned long, process_counts);
extern int nr_processes(void);
extern unsigned long nr_running(void);

53
kernel/pid.c
View file

@ -34,7 +34,6 @@ static int pidhash_shift;
static kmem_cache_t *pid_cachep;
int pid_max = PID_MAX_DEFAULT;
int last_pid;
#define RESERVED_PIDS 300
@ -43,7 +42,12 @@ int pid_max_max = PID_MAX_LIMIT;
#define BITS_PER_PAGE (PAGE_SIZE*8)
#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
#define mk_pid(map, off) (((map) - pidmap_array)*BITS_PER_PAGE + (off))
static inline int mk_pid(struct pspace *pspace, struct pidmap *map, int off)
{
return (map - pspace->pidmap)*BITS_PER_PAGE + off;
}
#define find_next_offset(map, off) \
find_next_zero_bit((map)->page, BITS_PER_PAGE, off)
@ -53,8 +57,12 @@ int pid_max_max = PID_MAX_LIMIT;
* value does not cause lots of bitmaps to be allocated, but
* the scheme scales to up to 4 million PIDs, runtime.
*/
static struct pidmap pidmap_array[PIDMAP_ENTRIES] =
{ [ 0 ... PIDMAP_ENTRIES-1 ] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } };
struct pspace init_pspace = {
.pidmap = {
[ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
},
.last_pid = 0
};
/*
* Note: disable interrupts while the pidmap_lock is held as an
@ -69,40 +77,41 @@ static struct pidmap pidmap_array[PIDMAP_ENTRIES] =
* irq handlers that take it we can leave the interrupts enabled.
* For now it is easier to be safe than to prove it can't happen.
*/
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
static fastcall void free_pidmap(int pid)
static fastcall void free_pidmap(struct pspace *pspace, int pid)
{
struct pidmap *map = pidmap_array + pid / BITS_PER_PAGE;
struct pidmap *map = pspace->pidmap + pid / BITS_PER_PAGE;
int offset = pid & BITS_PER_PAGE_MASK;
clear_bit(offset, map->page);
atomic_inc(&map->nr_free);
}
static int alloc_pidmap(void)
static int alloc_pidmap(struct pspace *pspace)
{
int i, offset, max_scan, pid, last = last_pid;
int i, offset, max_scan, pid, last = pspace->last_pid;
struct pidmap *map;
pid = last + 1;
if (pid >= pid_max)
pid = RESERVED_PIDS;
offset = pid & BITS_PER_PAGE_MASK;
map = &pidmap_array[pid/BITS_PER_PAGE];
map = &pspace->pidmap[pid/BITS_PER_PAGE];
max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
for (i = 0; i <= max_scan; ++i) {
if (unlikely(!map->page)) {
unsigned long page = get_zeroed_page(GFP_KERNEL);
void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
/*
* Free the page if someone raced with us
* installing it:
*/
spin_lock_irq(&pidmap_lock);
if (map->page)
free_page(page);
kfree(page);
else
map->page = (void *)page;
map->page = page;
spin_unlock_irq(&pidmap_lock);
if (unlikely(!map->page))
break;
@ -111,11 +120,11 @@ static int alloc_pidmap(void)
do {
if (!test_and_set_bit(offset, map->page)) {
atomic_dec(&map->nr_free);
last_pid = pid;
pspace->last_pid = pid;
return pid;
}
offset = find_next_offset(map, offset);
pid = mk_pid(map, offset);
pid = mk_pid(pspace, map, offset);
/*
* find_next_offset() found a bit, the pid from it
* is in-bounds, and if we fell back to the last
@ -126,16 +135,16 @@ static int alloc_pidmap(void)
(i != max_scan || pid < last ||
!((last+1) & BITS_PER_PAGE_MASK)));
}
if (map < &pidmap_array[(pid_max-1)/BITS_PER_PAGE]) {
if (map < &pspace->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
++map;
offset = 0;
} else {
map = &pidmap_array[0];
map = &pspace->pidmap[0];
offset = RESERVED_PIDS;
if (unlikely(last == offset))
break;
}
pid = mk_pid(map, offset);
pid = mk_pid(pspace, map, offset);
}
return -1;
}
@ -182,7 +191,7 @@ fastcall void free_pid(struct pid *pid)
hlist_del_rcu(&pid->pid_chain);
spin_unlock_irqrestore(&pidmap_lock, flags);
free_pidmap(pid->nr);
free_pidmap(&init_pspace, pid->nr);
call_rcu(&pid->rcu, delayed_put_pid);
}
@ -196,7 +205,7 @@ struct pid *alloc_pid(void)
if (!pid)
goto out;
nr = alloc_pidmap();
nr = alloc_pidmap(&init_pspace);
if (nr < 0)
goto out_free;
@ -363,10 +372,10 @@ void __init pidhash_init(void)
void __init pidmap_init(void)
{
pidmap_array->page = (void *)get_zeroed_page(GFP_KERNEL);
init_pspace.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
/* Reserve PID 0. We never call free_pidmap(0) */
set_bit(0, pidmap_array->page);
atomic_dec(&pidmap_array->nr_free);
set_bit(0, init_pspace.pidmap[0].page);
atomic_dec(&init_pspace.pidmap[0].nr_free);
pid_cachep = kmem_cache_create("pid", sizeof(struct pid),
__alignof__(struct pid),