From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>

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 <suka...@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <se...@us.ibm.com>
Reviewed-by: Oren Laadan <or...@cs.columbia.edu>
---
 kernel/fork.c |    5 +++--
 kernel/pid.c  |    9 ++++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index bd29592..e90cee5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1123,10 +1123,11 @@ 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 f618096..9c678ce 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -158,6 +158,7 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
        offset = pid & BITS_PER_PAGE_MASK;
        map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
        max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
+       rc = -EAGAIN;
        for (i = 0; i <= max_scan; ++i) {
                rc = alloc_pidmap_page(map);
                if (rc)
@@ -188,12 +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)
@@ -298,7 +301,7 @@ 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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