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-rw-r--r--fs/proc/proc_misc.c3
-rw-r--r--include/linux/pspace.h7
-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/pid.c53
4 files changed, 40 insertions, 24 deletions
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 66bc425..8d88e58 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -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);
}
diff --git a/include/linux/pspace.h b/include/linux/pspace.h
index a8a064b..91d48b8 100644
--- a/include/linux/pspace.h
+++ b/include/linux/pspace.h
@@ -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 */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index dd6c216..3b7c992 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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);
diff --git a/kernel/pid.c b/kernel/pid.c
index 8234bd0..89107b7 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -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),
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