On Wed, 2009-05-27 at 08:42 -0700, Sukadev Bhattiprolu wrote:
> From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> Date: Mon, 4 May 2009 01:17:40 -0700
> Subject: [PATCH 2/7] [PATCH] Have alloc_pidmap() return actual error code
>
> alloc_pidmap() can fail either because all pid numbers are in use or
> we can't allocate memory. 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 caller assume -ENOMEM, have alloc_pidmap() return
> the actual error.
>
> Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> ---
> 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 c0aaebe..fd72ad9 100644
> --- a/kernel/pid.c
> +++ b/kernel/pid.c
> @@ -151,6 +151,7 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
> {
> int i, offset, max_scan, pid, last = pid_ns->last_pid;
> struct pidmap *map;
> + int rc = -EAGAIN;
>
> pid = last + 1;
> if (pid >= pid_max)
> @@ -159,8 +160,10 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
> map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
> max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
> for (i = 0; i <= max_scan; ++i) {
> - if (alloc_pidmap_page(map))
> + if (alloc_pidmap_page(map)) {
> + rc = -ENOMEM;
> break;
> + }
OK, pet peeve time:
rc = alloc_pidmap_page(map);
if (rc)
break;
It saves the bracket and saves a line of assignment, *and* it clarifies
program flow.
-- Dave
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