As a next step in separating pid allocation from the idr, split off
the cyclic pid allocation cursor from the idr. Lift the cursor value
into the struct pid_namespace. Note that this involves temporarily
open-coding the cursor increment on allocation, but this is cleaned
up in the subsequent patch.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
arch/powerpc/platforms/cell/spufs/sched.c | 2 +-
fs/proc/loadavg.c | 2 +-
include/linux/pid_namespace.h | 1 +
kernel/pid.c | 6 ++++--
kernel/pid_namespace.c | 4 ++--
5 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 99bd027a7f7c..a2ed928d7658 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -1072,7 +1072,7 @@ static int show_spu_loadavg(struct seq_file *s, void *private)
LOAD_INT(c), LOAD_FRAC(c),
count_active_contexts(),
atomic_read(&nr_spu_contexts),
- idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
+ READ_ONCE(task_active_pid_ns(current)->pid_next) - 1);
return 0;
}
#endif
diff --git a/fs/proc/loadavg.c b/fs/proc/loadavg.c
index 817981e57223..2740b31b6461 100644
--- a/fs/proc/loadavg.c
+++ b/fs/proc/loadavg.c
@@ -22,7 +22,7 @@ static int loadavg_proc_show(struct seq_file *m, void *v)
LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]),
nr_running(), nr_threads,
- idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
+ READ_ONCE(task_active_pid_ns(current)->pid_next) - 1);
return 0;
}
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 07481bb87d4e..82c72482019d 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -18,6 +18,7 @@ struct fs_pin;
struct pid_namespace {
struct idr idr;
+ unsigned int pid_next;
struct rcu_head rcu;
unsigned int pid_allocated;
struct task_struct *child_reaper;
diff --git a/kernel/pid.c b/kernel/pid.c
index 3622f8b13143..2e2d33273c8e 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -75,6 +75,7 @@ int pid_max_max = PID_MAX_LIMIT;
struct pid_namespace init_pid_ns = {
.ns.count = REFCOUNT_INIT(2),
.idr = IDR_INIT(init_pid_ns.idr),
+ .pid_next = 0,
.pid_allocated = PIDNS_ADDING,
.level = 0,
.child_reaper = &init_task,
@@ -208,7 +209,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
* init really needs pid 1, but after reaching the
* maximum wrap back to RESERVED_PIDS
*/
- if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
+ if (tmp->pid_next > RESERVED_PIDS)
pid_min = RESERVED_PIDS;
/*
@@ -217,6 +218,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
*/
nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
pid_max, GFP_ATOMIC);
+ tmp->pid_next = nr + 1;
}
xa_unlock_irq(&tmp->idr.idr_rt);
idr_preload_end();
@@ -278,7 +280,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
/* On failure to allocate the first pid, reset the state */
if (tmp == ns && tmp->pid_allocated == PIDNS_ADDING)
- idr_set_cursor(&ns->idr, 0);
+ ns->pid_next = 0;
idr_remove(&tmp->idr, upid->nr);
xa_unlock_irq(&tmp->idr.idr_rt);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index f4f8cb0435b4..a53d20c5c85e 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -272,12 +272,12 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write,
* it should synchronize its usage with external means.
*/
- next = idr_get_cursor(&pid_ns->idr) - 1;
+ next = READ_ONCE(pid_ns->pid_next) - 1;
tmp.data = &next;
ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
if (!ret && write)
- idr_set_cursor(&pid_ns->idr, next + 1);
+ WRITE_ONCE(pid_ns->pid_next, next + 1);
return ret;
}
--
2.37.3
