From: Kent Overstreet <kent.overstreet@linux.dev>
To: Hongbo Li <lihongbo22@huawei.com>
Cc: bfoster@redhat.com, linux-bcachefs@vger.kernel.org
Subject: Re: [PATCH v2 1/2] bcachefs: eliminate the uninitialized compilation warning in bch2_reconstruct_snapshots
Date: Fri, 26 Apr 2024 00:04:40 -0400 [thread overview]
Message-ID: <klmvmcxhce2yd2xdmeyrnvxdvh25jykwwpzov7volswdzrrff3@4bpqb6erpimf> (raw)
In-Reply-To: <20240426032136.2551471-2-lihongbo22@huawei.com>
On Fri, Apr 26, 2024 at 11:21:35AM +0800, Hongbo Li wrote:
> When compiling the bcachefs-tools, the following compilation warning
> is reported:
> libbcachefs/snapshot.c: In function ‘bch2_reconstruct_snapshots’:
> libbcachefs/snapshot.c:915:19: warning: ‘tree_id’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> 915 | snapshot->v.tree = cpu_to_le32(tree_id);
> libbcachefs/snapshot.c:903:6: note: ‘tree_id’ was declared here
> 903 | u32 tree_id;
> | ^~~~~~~
>
> This is a false alert, because @tree_id is changed in
> bch2_snapshot_tree_create after it returns 0. And if this function
> returns other value, @tree_id wouldn't be used. Thus there should
> be nothing wrong in logical.
>
> Although the report itself is a false alert, we can still make it more
> explicit by setting the initial value of @tree_id to 0 (an invalid
> tree ID).
>
> Fixes: a292be3b68f3 ("bcachefs: Reconstruct missing snapshot nodes")
> Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
this works - applied
> ---
> v2:
> - Revise the code based on Kent's reviews.
>
> v1: https://lore.kernel.org/all/20240419074851.1583392-2-lihongbo22@huawei.com/T/#u
> ---
> ---
> fs/bcachefs/snapshot.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/bcachefs/snapshot.c b/fs/bcachefs/snapshot.c
> index 2368218070d4..3aa4686cc71f 100644
> --- a/fs/bcachefs/snapshot.c
> +++ b/fs/bcachefs/snapshot.c
> @@ -900,7 +900,8 @@ static int check_snapshot_exists(struct btree_trans *trans, u32 id)
> if (bch2_snapshot_equiv(c, id))
> return 0;
>
> - u32 tree_id;
> + /* 0 is an invalid tree ID */
> + u32 tree_id = 0;
> int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id);
> if (ret)
> return ret;
> --
> 2.34.1
>
next prev parent reply other threads:[~2024-04-26 4:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 3:21 [PATCH v2 0/2] eliminate the uninitialized compilation warning Hongbo Li
2024-04-26 3:21 ` [PATCH v2 1/2] bcachefs: eliminate the uninitialized compilation warning in bch2_reconstruct_snapshots Hongbo Li
2024-04-26 4:04 ` Kent Overstreet [this message]
2024-04-26 3:21 ` [PATCH v2 2/2] bcachefs: eliminate the uninitialized compilation warning in __do_six_trylock Hongbo Li
2024-04-26 4:04 ` Kent Overstreet
2024-04-26 6:09 ` Hongbo Li
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