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b=Mh1uVFU6JNai1F9LdjWZbPPl7KJBJc8d/UReYXUGnDCRuxJaxSzbVyb7uI1yVk0eY z4tCaC1+/jcFn4w7FOqjQ5BcWgrcLvdBZQzSVhYpDx26G+zrVLqFu14gCt8nS+Vi5h Ifn3lWC0ydfzvZHrDwRLhJVy/vnguhYMQZ6l43sez2ujouO57nd14+jJqIsNMuLjTZ qsftSArXs+pzZFPBoUFoOUWsuqKUAjQ/4tInVAjNM80oBXZLDQZQZZu14Wg+LXTNBF ChHo0rv201AbzjEGvwdUL3WGHrR1zPBnYNTp0o7SujROuhxgfybL+8NoXMIyzSXYsG 8x5XQRwJKsnHA== From: Pratyush Yadav To: David Matlack Cc: Alex Williamson , Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Lukas Wunner , =?utf-8?Q?M?= =?utf-8?Q?icha=C5=82?= Winiarski , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Thomas =?utf-8?Q?Hellstr=C3=B6m?= , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Subject: Re: [PATCH v2 06/22] vfio/pci: Retrieve preserved device files after Live Update In-Reply-To: (David Matlack's message of "Thu, 26 Feb 2026 23:40:41 +0000") References: <20260129212510.967611-1-dmatlack@google.com> <20260129212510.967611-7-dmatlack@google.com> <20260226155222.5452a741@shazbot.org> Date: Wed, 01 Apr 2026 14:36:44 +0000 Message-ID: <2vxzjyuqhhmr.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3AF934000F X-Stat-Signature: ymckspop4mddey47obmg8za7n5a7gnz1 X-Rspam-User: X-HE-Tag: 1775054214-619504 X-HE-Meta: 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 P2LcjpTI 6O1bqGPooysqOAJ4+eo+qN94uyxricZg7OVYY3i0d1cAS9dx8fEgbrAIYys8/S9/5meRF7gv8AT4+tu2eSiL+RBvJ4wxw+QLoxbUbf/035H+xKV88MbiLGlArR0bAt68voefdkPvBJElWOoP1P0l4e91D9NHmjA3c0r3lUXilO0f+/xM3TQqcqBuQ/Q6yza5kCfIb76PU8ff2VoiQp9Y6+dCTBaWHTnposqZo Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Feb 26 2026, David Matlack wrote: > On 2026-02-26 03:52 PM, Alex Williamson wrote: >> On Thu, 29 Jan 2026 21:24:53 +0000 David Matlack wrote: > >> > diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c >> > index 8ceca24ac136..935f84a35875 100644 >> > --- a/drivers/vfio/device_cdev.c >> > +++ b/drivers/vfio/device_cdev.c >> > @@ -52,6 +46,19 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep) >> > vfio_device_put_registration(device); >> > return ret; >> > } >> > +EXPORT_SYMBOL_GPL(__vfio_device_fops_cdev_open); >> >> I really dislike that we're exporting the underscore variant, which >> implies it's an internal function that the caller should understand the >> constraints, without outlining any constraints. >> >> I'm not sure what a good alternative is. We can drop fops since this >> isn't called from file_operations. Maybe vfio_device_cdev_open_file(). > > Ack. Due to the bug you pointed out below, I think the changes in this > file will look fairly different in the next version. But no matter what > I'll avoid exporting a underscore variant without outlining the > constraints. I haven't yet had a chance to read v3 so maybe you already solved this problem. But I dealt with some similar problems for the memfd patches [0] and the hugetlb patches [1]. What I did was to just use/add a internal header (mm/internal.h or mm/hugetlb_internal.h). This lets you share functions within your subsystem but avoid exporting everywhere else. I see that there already is drivers/vfio/vfio.h so perhaps you can use that to avoid exporting these functions outside the subsystem? [0] https://git.kernel.org/torvalds/c/ed6f45f81bf9 [1] https://lore.kernel.org/linux-mm/20251206230222.853493-6-pratyush@kernel.org/ [...] -- Regards, Pratyush Yadav