From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
To: Hanna Reitz <hreitz@redhat.com>, qemu-block@nongnu.org
Cc: "Kevin Wolf" <kwolf@redhat.com>, "Fam Zheng" <fam@euphon.net>,
"Vladimir Sementsov-Ogievskiy" <vsementsov@virtuozzo.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Juan Quintela" <quintela@redhat.com>,
qemu-devel@nongnu.org, "John Snow" <jsnow@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Markus Armbruster" <armbru@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Eric Blake" <eblake@redhat.com>
Subject: Re: [PATCH v5 10/31] block.c: modify .attach and .detach callbacks of child_of_bds
Date: Thu, 16 Dec 2021 17:05:24 +0100 [thread overview]
Message-ID: <937d15e5-4ba5-af84-f3bf-a4aa828f9d82@redhat.com> (raw)
In-Reply-To: <f996c8cc-c025-f8a5-c89d-cd8b8a94e7c5@redhat.com>
On 16/12/2021 15:57, Hanna Reitz wrote:
> On 24.11.21 07:43, Emanuele Giuseppe Esposito wrote:
>> According to the assertions put in the previous patch, we should
>> first drain and then modify the ->children list. In this way
>> we prevent other iothreads to read the list while it is being
>> updated.
>>
>> In this case, moving the drain won't cause any harm, because
>> child is a parameter of the drain function so it will still be
>> included in the operation, despite not being in the list.
>
> Sounds good.
Uhm.. I don't think this is useful at all. I was thinking to drop this
patch in v6.
My plans on subtree drains, ->children and ->parent lists are explained
in "Removal of Aiocontext lock and usage of subtree drains in aborted
transactions"
https://patchew.org/QEMU/20211213104014.69858-1-eesposit@redhat.com/
And as I say there, commit d736f119da makes sure that it is safe to
modify the graph even side a bdrv_subtree_drained_begin/end() section.
So this should be unnecessary.
Thank you,
Emanuele
>
>> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
>> ---
>> block.c | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index 522a273140..5516c84ec4 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -1416,6 +1416,7 @@ static void bdrv_child_cb_attach(BdrvChild *child)
>> {
>> BlockDriverState *bs = child->opaque;
>> + bdrv_apply_subtree_drain(child, bs);
>> assert_bdrv_graph_writable(bs);
>> QLIST_INSERT_HEAD(&bs->children, child, next);
>> @@ -1423,7 +1424,6 @@ static void bdrv_child_cb_attach(BdrvChild *child)
>> bdrv_backing_attach(child);
>> }
>> - bdrv_apply_subtree_drain(child, bs);
>
> I think we should also remove the empty line above.
>
> Hanna
>
>> }
>> static void bdrv_child_cb_detach(BdrvChild *child)
>> @@ -1434,10 +1434,9 @@ static void bdrv_child_cb_detach(BdrvChild *child)
>> bdrv_backing_detach(child);
>> }
>> - bdrv_unapply_subtree_drain(child, bs);
>> -
>> assert_bdrv_graph_writable(bs);
>> QLIST_REMOVE(child, next);
>> + bdrv_unapply_subtree_drain(child, bs);
>> }
>> static int bdrv_child_cb_update_filename(BdrvChild *c,
>> BlockDriverState *base,
>
next prev parent reply other threads:[~2021-12-16 16:06 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-24 6:43 [PATCH v5 00/31] block layer: split block APIs in global state and I/O Emanuele Giuseppe Esposito
2021-11-24 6:43 ` [PATCH v5 01/31] main-loop.h: introduce qemu_in_main_thread() Emanuele Giuseppe Esposito
2021-11-24 6:43 ` [PATCH v5 02/31] include/block/block: split header into I/O and global state API Emanuele Giuseppe Esposito
2021-11-24 6:43 ` [PATCH v5 03/31] assertions for block " Emanuele Giuseppe Esposito
2021-12-16 15:17 ` Hanna Reitz
2021-11-24 6:43 ` [PATCH v5 04/31] include/sysemu/block-backend: split header into I/O and global state (GS) API Emanuele Giuseppe Esposito
2021-12-10 14:21 ` Hanna Reitz
2021-11-24 6:43 ` [PATCH v5 05/31] block-backend: special comments for blk_set/get_perm due to fuse Emanuele Giuseppe Esposito
2021-12-10 14:38 ` Hanna Reitz
2021-12-15 8:57 ` Emanuele Giuseppe Esposito
2021-12-15 10:13 ` Emanuele Giuseppe Esposito
2021-12-16 14:00 ` Hanna Reitz
2021-11-24 6:43 ` [PATCH v5 06/31] block/block-backend.c: assertions for block-backend Emanuele Giuseppe Esposito
2021-12-10 15:37 ` Hanna Reitz
2021-11-24 6:43 ` [PATCH v5 07/31] include/block/block_int: split header into I/O and global state API Emanuele Giuseppe Esposito
2021-11-24 6:43 ` [PATCH v5 08/31] assertions for block_int " Emanuele Giuseppe Esposito
2021-11-24 6:43 ` [PATCH v5 09/31] block: introduce assert_bdrv_graph_writable Emanuele Giuseppe Esposito
2021-12-10 17:43 ` Hanna Reitz
2021-12-14 19:48 ` Emanuele Giuseppe Esposito
2021-12-16 14:01 ` Hanna Reitz
2021-11-24 6:43 ` [PATCH v5 10/31] block.c: modify .attach and .detach callbacks of child_of_bds Emanuele Giuseppe Esposito
2021-12-16 14:57 ` Hanna Reitz
2021-12-16 16:05 ` Emanuele Giuseppe Esposito [this message]
2021-12-16 16:12 ` Hanna Reitz
2021-11-24 6:43 ` [PATCH v5 11/31] include/block/blockjob_int.h: split header into I/O and GS API Emanuele Giuseppe Esposito
2021-11-24 6:43 ` [PATCH v5 12/31] assertions for blockjob_int.h Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 13/31] block.c: add assertions to static functions Emanuele Giuseppe Esposito
2021-12-16 16:08 ` Hanna Reitz
2021-12-16 16:39 ` Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 14/31] include/block/blockjob.h: global state API Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 15/31] assertions for blockjob.h " Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 16/31] include/sysemu/blockdev.h: " Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 17/31] assertions for blockdev.h " Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 18/31] include/block/snapshot: global state API + assertions Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 19/31] block/copy-before-write.h: " Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 20/31] block/coroutines: I/O API Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 21/31] block_int-common.h: split function pointers in BlockDriver Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 22/31] block_int-common.h: assertion in the callers of BlockDriver function pointers Emanuele Giuseppe Esposito
2021-12-16 18:43 ` Hanna Reitz
2021-12-17 15:53 ` Emanuele Giuseppe Esposito
2021-12-17 16:00 ` Hanna Reitz
2021-11-24 6:44 ` [PATCH v5 23/31] block_int-common.h: split function pointers in BdrvChildClass Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 24/31] block_int-common.h: assertions in the callers of BdrvChildClass function pointers Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 25/31] block-backend-common.h: split function pointers in BlockDevOps Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 26/31] job.h: split function pointers in JobDriver Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 27/31] job.h: assertions in the callers of JobDriver funcion pointers Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 28/31] block.c: assert BQL lock held in bdrv_co_invalidate_cache Emanuele Giuseppe Esposito
2021-12-17 11:04 ` Hanna Reitz
2021-12-17 16:38 ` Emanuele Giuseppe Esposito
2021-12-20 12:20 ` Emanuele Giuseppe Esposito
2021-12-23 17:11 ` Hanna Reitz
2022-01-19 15:57 ` Hanna Reitz
2022-01-19 17:44 ` Hanna Reitz
2022-01-19 18:34 ` Kevin Wolf
2022-01-20 13:22 ` Paolo Bonzini
2022-01-20 13:48 ` Kevin Wolf
2022-01-21 10:22 ` Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 29/31] jobs: introduce pre_run function in JobDriver Emanuele Giuseppe Esposito
2021-11-24 6:44 ` [PATCH v5 30/31] crypto: delegate permission functions to JobDriver .pre_run Emanuele Giuseppe Esposito
2021-12-17 12:29 ` Hanna Reitz
2021-12-17 14:32 ` Hanna Reitz
2021-12-20 15:47 ` Emanuele Giuseppe Esposito
2021-12-23 17:15 ` Hanna Reitz
2021-11-24 6:44 ` [PATCH v5 31/31] block.c: assertions to the block layer permissions API Emanuele Giuseppe Esposito
2021-11-29 13:32 ` [PATCH v5 00/31] block layer: split block APIs in global state and I/O Stefan Hajnoczi
2021-11-30 8:39 ` Emanuele Giuseppe Esposito
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=937d15e5-4ba5-af84-f3bf-a4aa828f9d82@redhat.com \
--to=eesposit@redhat.com \
--cc=armbru@redhat.com \
--cc=berrange@redhat.com \
--cc=dgilbert@redhat.com \
--cc=eblake@redhat.com \
--cc=ehabkost@redhat.com \
--cc=fam@euphon.net \
--cc=hreitz@redhat.com \
--cc=jsnow@redhat.com \
--cc=kwolf@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
--cc=quintela@redhat.com \
--cc=richard.henderson@linaro.org \
--cc=stefanha@redhat.com \
--cc=vsementsov@virtuozzo.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).