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Subject[PATCH 2/3] pids: Split alloc_pidmap into parts
The map's page allocation code is moved to separate function
to make clone-with-pids patching simpler.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

---
kernel/pid.c | 37 ++++++++++++++++++++++---------------
1 files changed, 22 insertions(+), 15 deletions(-)
diff --git a/kernel/pid.c b/kernel/pid.c
index 2d9704c..700dda3 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -159,6 +159,25 @@ static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid)
} while ((prev != last_write) && (pid_before(base, last_write, pid)));
}

+static int alloc_pidmap_page(struct pidmap *map)
+{
+ 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) {
+ map->page = page;
+ page = NULL;
+ }
+ spin_unlock_irq(&pidmap_lock);
+ kfree(page);
+
+ return map->page ? 0 : -1;
+}
+
static int alloc_pidmap(struct pid_namespace *pid_ns)
{
int i, offset, max_scan, pid, last = pid_ns->last_pid;
@@ -176,22 +195,10 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
*/
max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset;
for (i = 0; i <= max_scan; ++i) {
- if (unlikely(!map->page)) {
- 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) {
- map->page = page;
- page = NULL;
- }
- spin_unlock_irq(&pidmap_lock);
- kfree(page);
- if (unlikely(!map->page))
+ if (unlikely(!map->page))
+ if (alloc_pidmap_page(map))
break;
- }
+
if (likely(atomic_read(&map->nr_free))) {
do {
if (!test_and_set_bit(offset, map->page)) {
--
1.5.5.6

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