Messages in this thread |  | | Date | Mon, 21 Mar 2022 09:50:08 +0800 | Subject | Re: [PATCH] ocfs2: fix check if list iterator did find an element | From | Joseph Qi <> |
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On 3/20/22 4:31 AM, Jakob Koschel wrote: > Instead of setting 'res' to NULL, it should only be set if > the suitable element was found. > > In the original code 'res' would have been set to an incorrect pointer > if the list is empty. > The logic before iteration can make sure track_list won't be empty. Please refer the discussion via: https://lore.kernel.org/ocfs2-devel/bd0ec87e-b490-83dc-2363-5e5342c59fa4@linux.alibaba.com/T/#m96d4397930201d83d68677c33a9721ae8dbd8f15
Thanks, Joseph
> In preparation to limit the scope of the list iterator to the list > traversal loop, use a dedicated pointer pointing to the found element [1]. > > Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/ > Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com> > --- > fs/ocfs2/dlm/dlmdebug.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c > index d442cf5dda8a..be5e9ed7da8d 100644 > --- a/fs/ocfs2/dlm/dlmdebug.c > +++ b/fs/ocfs2/dlm/dlmdebug.c > @@ -541,7 +541,7 @@ static void *lockres_seq_start(struct seq_file *m, loff_t *pos) > struct debug_lockres *dl = m->private; > struct dlm_ctxt *dlm = dl->dl_ctxt; > struct dlm_lock_resource *oldres = dl->dl_res; > - struct dlm_lock_resource *res = NULL; > + struct dlm_lock_resource *res = NULL, *iter; > struct list_head *track_list; > > spin_lock(&dlm->track_lock); > @@ -556,11 +556,11 @@ static void *lockres_seq_start(struct seq_file *m, loff_t *pos) > } > } > > - list_for_each_entry(res, track_list, tracking) { > - if (&res->tracking == &dlm->tracking_list) > - res = NULL; > - else > - dlm_lockres_get(res); > + list_for_each_entry(iter, track_list, tracking) { > + if (&iter->tracking != &dlm->tracking_list) { > + dlm_lockres_get(iter); > + res = iter; > + } > break; > } > spin_unlock(&dlm->track_lock); > > base-commit: 34e047aa16c0123bbae8e2f6df33e5ecc1f56601 > -- > 2.25.1
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