From: Qu Wenruo <wqu@suse.de>
To: Nikolay Borisov <nborisov@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning
Date: Fri, 16 Nov 2018 16:16:39 +0800 [thread overview]
Message-ID: <b3a56874-b52e-5dbb-74fd-b1a40757965c@suse.de> (raw)
In-Reply-To: <05314eb4-29e5-8c30-05ca-5566ec12eb83@suse.com>
On 2018/11/16 下午4:13, Nikolay Borisov wrote:
>
>
> On 16.11.18 г. 9:54 ч., Qu Wenruo wrote:
>> The only location is the following code:
>>
>> int level = path->lowest_level + 1;
>> BUG_ON(path->lowest_level + 1 >= BTRFS_MAX_LEVEL);
>> while(level < BTRFS_MAX_LEVEL) {
>> slot = path->slots[level] + 1;
>> ...
>> }
>> path->slots[level] = slot;
>>
>> Again, it's the stupid compiler needs some hint for the fact that
>> we will always enter the while loop for at least once, thus @slot should
>> always be initialized.
>>
>> Fix it by assign level after the BUG_ON(), so the stupid compiler knows
>> we will always go into the while loop.
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>
> I don't get this warning on gcc 7.3. Also from your changelog it's not
> really clear what the compiler is confused about.
My gcc 8.2.1 reports it with "make W=1"
I'll just update the commit message with the original report:
ctree.c: In function 'btrfs_next_sibling_tree_block':
ctree.c:2990:21: warning: 'slot' may be used uninitialized in this
function [-Wmaybe-uninitialized]
path->slots[level] = slot;
~~~~~~~~~~~~~~~~~~~^~~~~~
Thanks,
Qu
>
> Codewise lgtm:
>
> Reviewed-by: Nikolay Borisov <nborisov@suse.com>
>
>> ---
>> ctree.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/ctree.c b/ctree.c
>> index 46e2ccedc0bf..9c9cb0dfdbf2 100644
>> --- a/ctree.c
>> +++ b/ctree.c
>> @@ -2961,11 +2961,12 @@ int btrfs_next_sibling_tree_block(struct btrfs_fs_info *fs_info,
>> struct btrfs_path *path)
>> {
>> int slot;
>> - int level = path->lowest_level + 1;
>> + int level;
>> struct extent_buffer *c;
>> struct extent_buffer *next = NULL;
>>
>> BUG_ON(path->lowest_level + 1 >= BTRFS_MAX_LEVEL);
>> + level = path->lowest_level + 1;
>> while(level < BTRFS_MAX_LEVEL) {
>> if (!path->nodes[level])
>> return 1;
>>
next prev parent reply other threads:[~2018-11-16 8:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-16 7:54 [PATCH 0/9] btrfs-progs: Make W=1 clean (no "again") Qu Wenruo
2018-11-16 7:54 ` [PATCH 1/9] btrfs-progs: Makefile.extrawarn: Import cc-disable-warning Qu Wenruo
2018-12-04 11:04 ` David Sterba
2018-11-16 7:54 ` [PATCH 2/9] btrfs-progs: fix gcc8 default build warning caused by '-Wformat-truncation' Qu Wenruo
2018-12-04 11:10 ` David Sterba
2018-12-04 12:21 ` Qu Wenruo
2018-11-16 7:54 ` [PATCH 3/9] btrfs-progs: Makefile.extrawarn: Don't warn on sign compare Qu Wenruo
2018-11-16 8:00 ` [PATCH v1.1 " Qu Wenruo
2018-12-04 11:10 ` David Sterba
2018-11-16 7:54 ` [PATCH 4/9] btrfs-progs: Fix Wempty-body warning Qu Wenruo
2018-11-16 8:01 ` Nikolay Borisov
2018-11-16 7:54 ` [PATCH 5/9] btrfs-progs: Fix Wimplicit-fallthrough warning Qu Wenruo
2018-11-16 8:04 ` Nikolay Borisov
2018-11-16 8:10 ` Qu Wenruo
2018-11-16 7:54 ` [PATCH 6/9] btrfs-progs: Fix Wsuggest-attribute=format warning Qu Wenruo
2018-11-16 8:06 ` Nikolay Borisov
2018-11-16 7:54 ` [PATCH 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning Qu Wenruo
2018-11-16 8:13 ` Nikolay Borisov
2018-11-16 8:16 ` Qu Wenruo [this message]
2018-11-16 8:22 ` [PATCH v1.1 " Qu Wenruo
2018-11-16 8:24 ` Nikolay Borisov
2018-12-04 12:17 ` [PATCH " David Sterba
2018-12-04 12:22 ` Adam Borowski
2018-12-04 12:42 ` Nikolay Borisov
2018-12-05 5:38 ` Qu Wenruo
2018-11-16 7:54 ` [PATCH 8/9] btrfs-progs: Fix Wtype-limits warning Qu Wenruo
2018-11-16 8:07 ` Nikolay Borisov
2018-11-16 7:54 ` [PATCH 9/9] btrfs-progs: Cleanup warning reported by -Wmissing-prototypes except free space tree Qu Wenruo
2018-11-16 8:04 ` [PATCH v1.1 9/9] btrfs-progs: Cleanup warning reported by -Wmissing-prototypes Qu Wenruo
2018-11-16 8:14 ` Nikolay Borisov
2018-12-04 12:22 ` David Sterba
2018-12-04 12:24 ` Qu Wenruo
2018-12-04 12:48 ` David Sterba
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