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Diffstat (limited to 'kernel/pid.c')
-rw-r--r--kernel/pid.c111
1 files changed, 82 insertions, 29 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index 8387e8c6819..b914392085f 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -26,6 +26,7 @@
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/hash.h>
+#include <linux/pspace.h>
#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
static struct hlist_head *pid_hash;
@@ -33,17 +34,20 @@ static int pidhash_shift;
static kmem_cache_t *pid_cachep;
int pid_max = PID_MAX_DEFAULT;
-int last_pid;
#define RESERVED_PIDS 300
int pid_max_min = RESERVED_PIDS + 1;
int pid_max_max = PID_MAX_LIMIT;
-#define PIDMAP_ENTRIES ((PID_MAX_LIMIT + 8*PAGE_SIZE - 1)/PAGE_SIZE/8)
#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)
@@ -53,13 +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.
*/
-typedef struct pidmap {
- atomic_t nr_free;
- void *page;
-} pidmap_t;
-
-static pidmap_t 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
@@ -74,40 +77,41 @@ static pidmap_t 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)
{
- pidmap_t *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;
- pidmap_t *map;
+ 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;
@@ -116,11 +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
@@ -131,16 +135,34 @@ 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;
+}
+
+static int next_pidmap(struct pspace *pspace, int last)
+{
+ int offset;
+ struct pidmap *map, *end;
+
+ offset = (last + 1) & BITS_PER_PAGE_MASK;
+ map = &pspace->pidmap[(last + 1)/BITS_PER_PAGE];
+ end = &pspace->pidmap[PIDMAP_ENTRIES];
+ for (; map < end; map++, offset = 0) {
+ if (unlikely(!map->page))
+ continue;
+ offset = find_next_bit((map)->page, BITS_PER_PAGE, offset);
+ if (offset < BITS_PER_PAGE)
+ return mk_pid(pspace, map, offset);
}
return -1;
}
@@ -153,6 +175,7 @@ fastcall void put_pid(struct pid *pid)
atomic_dec_and_test(&pid->count))
kmem_cache_free(pid_cachep, pid);
}
+EXPORT_SYMBOL_GPL(put_pid);
static void delayed_put_pid(struct rcu_head *rhp)
{
@@ -169,7 +192,7 @@ 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);
}
@@ -183,7 +206,7 @@ struct pid *alloc_pid(void)
if (!pid)
goto out;
- nr = alloc_pidmap();
+ nr = alloc_pidmap(&init_pspace);
if (nr < 0)
goto out_free;
@@ -217,6 +240,7 @@ struct pid * fastcall find_pid(int nr)
}
return NULL;
}
+EXPORT_SYMBOL_GPL(find_pid);
int fastcall attach_pid(struct task_struct *task, enum pid_type type, int nr)
{
@@ -280,6 +304,15 @@ struct task_struct *find_task_by_pid_type(int type, int nr)
EXPORT_SYMBOL(find_task_by_pid_type);
+struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
+{
+ struct pid *pid;
+ rcu_read_lock();
+ pid = get_pid(task->pids[type].pid);
+ rcu_read_unlock();
+ return pid;
+}
+
struct task_struct *fastcall get_pid_task(struct pid *pid, enum pid_type type)
{
struct task_struct *result;
@@ -303,6 +336,26 @@ struct pid *find_get_pid(pid_t nr)
}
/*
+ * Used by proc to find the first pid that is greater then or equal to nr.
+ *
+ * If there is a pid at nr this function is exactly the same as find_pid.
+ */
+struct pid *find_ge_pid(int nr)
+{
+ struct pid *pid;
+
+ do {
+ pid = find_pid(nr);
+ if (pid)
+ break;
+ nr = next_pidmap(&init_pspace, nr);
+ } while (nr > 0);
+
+ return pid;
+}
+EXPORT_SYMBOL_GPL(find_get_pid);
+
+/*
* The pid hash table is scaled according to the amount of memory in the
* machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or
* more.
@@ -329,10 +382,10 @@ 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),
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-27 21:37:44 +0000