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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Eugenio Perez Martin <eperezma@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>,
	Laurent Vivier <lvivier@redhat.com>,
	virtualization@lists.linux.dev,
	Maxime Coquelin <mcoqueli@redhat.com>, Cindy Lu <lulu@redhat.com>,
	linux-kernel@vger.kernel.org,
	Yongji Xie <xieyongji@bytedance.com>,
	Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
	Stefano Garzarella <sgarzare@redhat.com>
Subject: Re: [PATCH v9 5/6] vduse: add vq group asid support
Date: Wed, 19 Nov 2025 04:32:20 -0500	[thread overview]
Message-ID: <20251119042923-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CAJaqyWeVCZOyBu2jPEc3iyP1uP=mzs2z7X=4JfYdBS6fLvPdxA@mail.gmail.com>

On Wed, Nov 19, 2025 at 10:26:43AM +0100, Eugenio Perez Martin wrote:
> > But this is not the logic that is
> > implemented in this patch as there's no synchronize_rcu() in the
> > vduse_set_group_asid_nomsg().
> 
> We only set the pointer on the writer's side, we do nothing like
> freeing resources. Should we set the pointer before or after
> syncrhonize_rcu()?

synchronize_rcu is called after writer makes it's changes.

> What do we need to do on the other side of
> syncrhonize_rcu()?

Presumably, return so the caller knows the as has been updated.

However, user-triggerable synchronize_rcu() is almost always a bug.

If that's what is going on, you want srcu.


-- 
MST


  reply	other threads:[~2025-11-19  9:32 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-13 11:55 [PATCH v9 0/6] Add multiple address spaces support to VDUSE Eugenio Pérez
2025-11-13 11:55 ` [PATCH v9 1/6] vduse: add v1 API definition Eugenio Pérez
2025-11-13 11:55 ` [PATCH v9 2/6] vduse: add vq group support Eugenio Pérez
2025-11-13 11:55 ` [PATCH v9 3/6] vduse: return internal vq group struct as map token Eugenio Pérez
2025-11-13 11:55 ` [PATCH v9 4/6] vduse: refactor vdpa_dev_add for goto err handling Eugenio Pérez
2025-11-13 11:55 ` [PATCH v9 5/6] vduse: add vq group asid support Eugenio Pérez
2025-11-14  0:55   ` Jason Wang
2025-11-14 11:25     ` Eugenio Perez Martin
2025-11-17  4:23       ` Jason Wang
2025-11-17 12:15         ` Eugenio Perez Martin
2025-11-19  2:38           ` Jason Wang
2025-11-19  9:26             ` Eugenio Perez Martin
2025-11-19  9:32               ` Michael S. Tsirkin [this message]
2025-11-19 10:38                 ` Eugenio Perez Martin
2025-11-19 12:29                   ` Michael S. Tsirkin
2025-11-20  1:37               ` Jason Wang
2025-12-03  7:57                 ` Eugenio Perez Martin
2025-12-04  2:15                   ` Jason Wang
2025-12-04  8:32                     ` Eugenio Perez Martin
2025-12-05  1:51                       ` Jason Wang
2025-12-05 15:30                         ` Eugenio Perez Martin
2025-12-08  2:58                           ` Jason Wang
2025-11-17 10:50       ` Michael S. Tsirkin
2025-11-17 12:16         ` Eugenio Perez Martin
2025-11-17  3:10   ` 谢永吉
2025-11-17  9:08     ` Eugenio Perez Martin
2025-11-13 11:55 ` [PATCH v9 6/6] vduse: bump version number Eugenio Pérez

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