Linux PCI subsystem development
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From: "Alexandre Courbot" <acourbot@nvidia.com>
To: "Danilo Krummrich" <dakr@kernel.org>
Cc: "Zhi Wang" <zhiw@nvidia.com>, <airlied@gmail.com>,
	<simona@ffwll.ch>, <ojeda@kernel.org>, <alex.gaynor@gmail.com>,
	<boqun.feng@gmail.com>, <gary@garyguo.net>,
	<bjorn3_gh@protonmail.com>, <lossin@kernel.org>,
	<a.hindborg@kernel.org>, <aliceryhl@google.com>,
	<tmgross@umich.edu>, <jhubbard@nvidia.com>,
	<ecourtney@nvidia.com>, <joelagnelf@nvidia.com>,
	<apopple@nvidia.com>, <cjia@nvidia.com>, <smitra@nvidia.com>,
	<kjaju@nvidia.com>, <alkumar@nvidia.com>, <ankita@nvidia.com>,
	<aniketa@nvidia.com>, <kwankhede@nvidia.com>,
	<targupta@nvidia.com>, <nova-gpu@lists.linux.dev>,
	<linux-kernel@vger.kernel.org>, <zhiwang@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"David Laight" <david.laight.linux@gmail.com>,
	<linux-pci@vger.kernel.org>
Subject: Re: [PATCH v4 2/6] rust: pci: add sriov_get_totalvfs() helper
Date: Thu, 16 Jul 2026 07:56:06 -0700	[thread overview]
Message-ID: <DK02ZSVH8H43.W1NXXI0GNYGR@nvidia.com> (raw)
In-Reply-To: <DJUEWLO5YJFE.3BKHFV0J9K3TA@kernel.org>

On Thu Jul 9, 2026 at 4:00 PM PDT, Danilo Krummrich wrote:
> On Thu Jul 9, 2026 at 5:02 PM CEST, Zhi Wang wrote:
>> +    /// Returns the total number of VFs, or [`None`] if SR-IOV is not available.
>> +    #[inline]
>> +    pub fn sriov_get_totalvfs(&self) -> Option<NonZero<u16>> {
>> +        // SAFETY: `self.as_raw()` is a valid pointer to a `struct pci_dev`.
>> +        let total_vfs = unsafe { bindings::pci_sriov_get_totalvfs(self.as_raw()) };
>> +
>> +        // CAST: The C function returns `unsigned int`, but the value originates
>> +        // from TotalVFs/driver_max_VFs (which are defined as `u16`), so this cast
>> +        // cannot truncate.
>> +        NonZero::new(total_vfs as u16)
>> +    }
>>  }
>>  
>>  impl<'a> Device<device::Core<'a>> {
>
> It is not a problem yet, but sriov_get_totalvfs() should go into the
> Device<Core> impl above.
>
> Once we also have sriov_set_totalvfs() this would otherwise be a potential data
> race.

With the above addressed,

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>

      reply	other threads:[~2026-07-16 14:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20260709150206.1046839-1-zhiw@nvidia.com>
2026-07-09 15:02 ` [PATCH v4 1/6] PCI/IOV: Return unsigned int from pci_sriov_get_totalvfs() Zhi Wang
2026-07-09 22:46   ` Bjorn Helgaas
2026-07-09 22:58     ` Danilo Krummrich
2026-07-09 15:02 ` [PATCH v4 2/6] rust: pci: add sriov_get_totalvfs() helper Zhi Wang
2026-07-09 23:00   ` Danilo Krummrich
2026-07-16 14:56     ` Alexandre Courbot [this message]

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