All of lore.kernel.org
 help / color / mirror / Atom feed
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: Alberto Garcia <berto@igalia.com>, qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, armbru@redhat.com, eblake@redhat.com,
	jsnow@redhat.com, stefanha@redhat.com, pbonzini@redhat.com,
	pavel.dovgaluk@ispras.ru, ari@tuxera.com, mreitz@redhat.com,
	kwolf@redhat.com
Subject: Re: [PATCH v7 08/14] block/qcow2: qcow2_get_specific_info(): drop error propagation
Date: Fri, 5 Feb 2021 14:52:03 +0300	[thread overview]
Message-ID: <f5c4c064-166f-a2bd-8d86-1c25a3c26646@virtuozzo.com> (raw)
In-Reply-To: <w51lfc2bv08.fsf@maestria.local.igalia.com>

05.02.2021 14:43, Alberto Garcia wrote:
> On Tue 02 Feb 2021 01:49:50 PM CET, Vladimir Sementsov-Ogievskiy wrote:
>> -Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
>> -                                                Error **errp)
>> +bool qcow2_get_bitmap_info_list(BlockDriverState *bs,
>> +                                Qcow2BitmapInfoList **info_list, Error **errp)
>>   {
>>       BDRVQcow2State *s = bs->opaque;
>>       Qcow2BitmapList *bm_list;
>>       Qcow2Bitmap *bm;
>> -    Qcow2BitmapInfoList *list = NULL;
>> -    Qcow2BitmapInfoList **tail = &list;
>>   
>>       if (s->nb_bitmaps == 0) {
>> -        return NULL;
>> +        *info_list = NULL;
>> +        return true;
>>       }
>>   
>>       bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
>>                                  s->bitmap_directory_size, errp);
>> -    if (bm_list == NULL) {
>> -        return NULL;
>> +    if (!bm_list) {
>> +        return false;
>>       }
>>   
>> +    *info_list = NULL;
>> +
>>       QSIMPLEQ_FOREACH(bm, bm_list, entry) {
>>           Qcow2BitmapInfo *info = g_new0(Qcow2BitmapInfo, 1);
>>           info->granularity = 1U << bm->granularity_bits;
>>           info->name = g_strdup(bm->name);
>>           info->flags = get_bitmap_info_flags(bm->flags & ~BME_RESERVED_FLAGS);
>> -        QAPI_LIST_APPEND(tail, info);
>> +        QAPI_LIST_APPEND(info_list, info);
>>       }
>>   
>>       bitmap_list_free(bm_list);
>>   
>> -    return list;
>> +    return true;
>>   }
> 
> Maybe I'm reading this wrong but...
> 
> In the original code you had the head and tail of the list ('list' and
> 'tail') then you would append items to the tail and finally return the
> head.
> 
> However the new code only uses and updates 'info_list' and it does not
> keep the head anywhere, so what the caller gets is a pointer to the
> tail.
> 

No. *info_list is modified only on the first loop iteration. And than info_list is switched to &(*(info_list))->next, so on second iteration we will modify @next field of first element, not original *info_list.



-- 
Best regards,
Vladimir


  reply	other threads:[~2021-02-05 11:53 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02 12:49 [PATCH v7 00/14] block: deal with errp: part I Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 01/14] block: return status from bdrv_append and friends Vladimir Sementsov-Ogievskiy
2021-02-05 11:16   ` Alberto Garcia
2021-02-05 11:26     ` Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 02/14] block: use return status of bdrv_append() Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 03/14] block: check return value of bdrv_open_child and drop error propagation Vladimir Sementsov-Ogievskiy
2021-02-12 23:13   ` Eric Blake
2021-02-15  9:22     ` Kevin Wolf
2021-02-15 20:04       ` Eric Blake
2021-02-16  5:03         ` Vladimir Sementsov-Ogievskiy
2021-02-16  9:02           ` Kevin Wolf
2021-02-02 12:49 ` [PATCH v7 04/14] blockdev: fix drive_backup_prepare() missed error Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 05/14] block: drop extra error propagation for bdrv_set_backing_hd Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 06/14] block/mirror: drop extra error propagation in commit_active_start() Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 07/14] blockjob: return status from block_job_set_speed() Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 08/14] block/qcow2: qcow2_get_specific_info(): drop error propagation Vladimir Sementsov-Ogievskiy
2021-02-05 11:43   ` Alberto Garcia
2021-02-05 11:52     ` Vladimir Sementsov-Ogievskiy [this message]
2021-02-05 12:01       ` Alberto Garcia
2021-02-12 19:44       ` Eric Blake
2021-02-02 12:49 ` [PATCH v7 09/14] block/qcow2-bitmap: improve qcow2_load_dirty_bitmaps() interface Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 10/14] block/qcow2-bitmap: return status from qcow2_store_persistent_dirty_bitmaps Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 11/14] block/qcow2: read_cache_sizes: return status value Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 12/14] block/qcow2: simplify qcow2_co_invalidate_cache() Vladimir Sementsov-Ogievskiy
2021-02-02 12:49 ` [PATCH v7 13/14] block/qed: bdrv_qed_do_open: deal with errp Vladimir Sementsov-Ogievskiy
2021-02-12 22:18   ` Eric Blake
2021-02-02 12:49 ` [PATCH v7 14/14] block/qcow2: refactor qcow2_update_options_prepare error paths Vladimir Sementsov-Ogievskiy

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=f5c4c064-166f-a2bd-8d86-1c25a3c26646@virtuozzo.com \
    --to=vsementsov@virtuozzo.com \
    --cc=ari@tuxera.com \
    --cc=armbru@redhat.com \
    --cc=berto@igalia.com \
    --cc=eblake@redhat.com \
    --cc=jsnow@redhat.com \
    --cc=kwolf@redhat.com \
    --cc=mreitz@redhat.com \
    --cc=pavel.dovgaluk@ispras.ru \
    --cc=pbonzini@redhat.com \
    --cc=qemu-block@nongnu.org \
    --cc=qemu-devel@nongnu.org \
    --cc=stefanha@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.