Messages in this thread Patch in this message | | | Subject | Re: [PATCH] ubifs: Remove a redundant null check on pointer lp | From | Zhihao Cheng <> | Date | Tue, 22 Jun 2021 10:38:52 +0800 |
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在 2021/6/21 23:22, Colin King 写道: > From: Colin Ian King <colin.king@canonical.com> > > An earlier fix to replace an IS_ERR check on lp with a null check > on lp didn't remove a following null check on lp. The second null > check is redundant and can be removed. > > Addresses-Coverity: ("Logically dead code") > Fixes: c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > fs/ubifs/gc.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c > index 7cc22d7317ea..465beea52176 100644 > --- a/fs/ubifs/gc.c > +++ b/fs/ubifs/gc.c > @@ -899,8 +899,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c) > err = -ENOMEM; > goto out; > } Hi Colin, I just found out about it today thanks to your patch. Commit c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check") did import a new problem that ubifs_gc_start_commit() may return -ENOMEM while syncing fs. I guess ubifs_fast_find_frdi_idx() return NULL pointer is the termination condition in while-loop, which means we cannot get a freeable index LEB in ubifs_gc_start_commit().
> - if (!lp) > - break; > idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); > if (!idx_gc) { > err = -ENOMEM; > BTW, the following modifications may be what you want? diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c index 7cc22d7317ea..b1f276599b04 100644 --- a/fs/ubifs/gc.c +++ b/fs/ubifs/gc.c @@ -895,10 +895,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c) /* Record index freeable LEBs for unmapping after commit */ while (1) { lp = ubifs_fast_find_frdi_idx(c); - if (!lp) { - err = -ENOMEM; - goto out; - } if (!lp) break; idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);
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