[PATCH v21 002/100] eclone (2/11): Have alloc_pidmap() return actual error code

[Oren Laadan]

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.

Changelog[v1]:
        - [Oren Laadan] Rebase to kernel 2.6.33

Cc: linux-...@vger.kernel.org
Cc: x...@kernel.org
Cc: linux-s...@vger.kernel.org
Cc: linuxppc-...@ozlabs.org
Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Acked-by: Serge E. Hallyn <se...@us.ibm.com>
Tested-by: Serge E. Hallyn <se...@us.ibm.com>
Reviewed-by: Oren Laadan <or...@cs.columbia.edu>
---
 kernel/fork.c |    5 +++--
 kernel/pid.c  |   10 ++++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 44b0791..afdfb08 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1147,10 +1147,11 @@ 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 52a371a..8330488 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -160,7 +160,7 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
        for (i = 0; i <= max_scan; ++i) {
                if (unlikely(!map->page))
                        if (alloc_pidmap_page(map) < 0)
-                               break;
+                               return -ENOMEM;
                if (likely(atomic_read(&map->nr_free))) {
                        do {
                                if (!test_and_set_bit(offset, map->page)) {
@@ -191,7 +191,7 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
                }
                pid = mk_pid(pid_ns, map, offset);
        }
-       return -1;
+       return -EBUSY;
 }
 
 int next_pidmap(struct pid_namespace *pid_ns, int last)
@@ -260,8 +260,10 @@ 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--) {
@@ -295,7 +297,7 @@ out_free:
                free_pidmap(pid->numbers + i);
 
        kmem_cache_free(ns->pid_cachep, pid);
-       pid = NULL;
+       pid = ERR_PTR(nr);
        goto out;
 }
 
-- 
1.6.3.3

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