On Sat, May 30, 2009 at 05:01:15PM -0700, Sukadev Bhattiprolu wrote:
>
>From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
>Date: Mon, 4 May 2009 01:17:40 -0700
>Subject: [RFC][v3][PATCH 2/7] 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 <suka...@linux.vnet.ibm.com>
>Acked-by: Serge Hallyn <se...@us.ibm.com>
>Reviewed-by: Oren Laadan <or...@cs.columbia.edu>

Reviewed-by: WANG Cong <xiyou.wangc...@gmail.com>



>---
> 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 b9e2edd..f8411a8 100644
>--- a/kernel/fork.c
>+++ b/kernel/fork.c
>@@ -1119,10 +1119,11 @@ 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 9ff33cc..b2d6a19 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;
> }
> 
>-- 
>1.5.2.5
>
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