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Subject[v13][PATCH 02/12] Have alloc_pidmap() return actual error code

From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Subject: [v13][PATCH 02/12] Have alloc_pidmap() return actual error code

alloc_pidmap() can fail either because all pid numbers are in use or
because memory allocation failed. With support for setting a specific
pid number, alloc_pidmap() would also fail if either the given pid
number is invalid or in use.

Rather than have callers assume -ENOMEM, have alloc_pidmap() return
the actual error.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Reviewed-by: Oren Laadan <orenl@cs.columbia.edu>
---
kernel/fork.c | 5 +++--
kernel/pid.c | 14 +++++++++-----
2 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 166b8c4..8053c10 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1156,10 +1156,11 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto bad_fork_cleanup_io;

if (pid != &init_struct_pid) {
- retval = -ENOMEM;
pid = alloc_pid(p->nsproxy->pid_ns);
- if (!pid)
+ if (IS_ERR(pid)) {
+ retval = PTR_ERR(pid);
goto bad_fork_cleanup_io;
+ }

if (clone_flags & CLONE_NEWPID) {
retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
diff --git a/kernel/pid.c b/kernel/pid.c
index 7d4bb6e..c4d9914 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -150,7 +150,7 @@ static int alloc_pidmap_page(struct pidmap *map)
static int alloc_pidmap(struct pid_namespace *pid_ns)
{
int i, offset, max_scan, pid, last = pid_ns->last_pid;
- int rc;
+ int rc = -EAGAIN;
struct pidmap *map;

pid = last + 1;
@@ -189,12 +189,14 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
} else {
map = &pid_ns->pidmap[0];
offset = RESERVED_PIDS;
- if (unlikely(last == offset))
+ if (unlikely(last == offset)) {
+ rc = -EAGAIN;
break;
+ }
}
pid = mk_pid(pid_ns, map, offset);
}
- return -1;
+ return rc;
}

int next_pidmap(struct pid_namespace *pid_ns, int last)
@@ -263,8 +265,10 @@ struct pid *alloc_pid(struct pid_namespace *ns)
struct upid *upid;

pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
- if (!pid)
+ if (!pid) {
+ pid = ERR_PTR(-ENOMEM);
goto out;
+ }

tmp = ns;
for (i = ns->level; i >= 0; i--) {
@@ -299,7 +303,7 @@ out_free:
free_pidmap(pid->numbers + i);

kmem_cache_free(ns->pid_cachep, pid);
- pid = NULL;
+ pid = ERR_PTR(nr);
goto out;
}

--
1.6.0.4


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