Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed

[Cong Wang]

On 09/04/2012 05:22 PM, yan yan wrote:
> 2012/9/4 Cong Wang <xiyou.wangcong@xxxxxxxxx>:
> > On 09/03/2012 10:14 PM, yan wrote:
> > > Signed-off-by: yan <clouds.yan@xxxxxxxxx>
> >
> >
> > Please provide a changelog to explain why we need this patch.
>
> I think the title is self explained.
>
>
> > > ---
> > >    fs/proc/generic.c |    2 +-
> > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c
> > > index b3647fe..9e8f631 100644
> > > --- a/fs/proc/generic.c
> > > +++ b/fs/proc/generic.c
> > > @@ -427,7 +427,7 @@ struct dentry *proc_lookup_de(struct proc_dir_entry
> > > *de, struct inode *dir,
> > >                  if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
> > >                          pde_get(de);
> > >                          spin_unlock(&proc_subdir_lock);
> > > -                       error = -EINVAL;
> > > +                       error = -ENOMEM;
> >
> >
> > Why the !memcmp() case is related with ENOMEM ??
>
> We are presetting 'error' here. The following proc_get_inode() will try
> to get an inode, either from inode cache or allocate a new one (and fill it).
>
> If we get a NULL inode, that means allocation failed. That's how
> ENOMEM involved.

Then the following patch is probably better than yours:


diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index b3647fe..6b22913 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -427,12 +427,16 @@ struct dentry *proc_lookup_de(struct 
proc_dir_entry *de, struct inode *dir,
                if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
                        pde_get(de);
                        spin_unlock(&proc_subdir_lock);
-                       error = -EINVAL;
                        inode = proc_get_inode(dir->i_sb, de);
+                       if (!inode) {
+                               error = -ENOMEM;
+                               goto out_put;
+                       }
                        goto out_unlock;
                }
        }
        spin_unlock(&proc_subdir_lock);
+
 out_unlock:

        if (inode) {
@@ -440,6 +444,8 @@ out_unlock:
                d_add(dentry, inode);
                return NULL;
        }
+out_put:
+
        if (de)
                pde_put(de);
        return ERR_PTR(error);


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