| Message ID | 20250319203112.131959-3-dakr@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | Implement TryFrom<&Device> for bus specific devices | expand |
On Wed, Mar 19, 2025 at 09:30:26PM +0100, Danilo Krummrich wrote: > Implement bus_type_raw(), which returns a raw pointer to the device' > struct bus_type. > > This is useful for bus devices, to implement the following trait. > > impl TryFrom<&Device> for &pci::Device > > With this a caller can try to get the bus specific device from a generic > device in a safe way. try_from() will only succeed if the generic > device' bus type pointer matches the pointer of the bus' type. > > Signed-off-by: Danilo Krummrich <dakr@kernel.org> > --- > rust/kernel/device.rs | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs > index 76b341441f3f..e2de0efd4a27 100644 > --- a/rust/kernel/device.rs > +++ b/rust/kernel/device.rs > @@ -78,6 +78,13 @@ pub fn parent<'a>(&self) -> Option<&'a Self> { > } > } > > + /// Returns a raw pointer to the device' bus type. > + #[expect(unused)] > + pub(crate) fn bus_type_raw(&self) -> *const bindings::bus_type { > + // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. Is this field immutable? > + unsafe { (*self.as_raw()).bus } > + } > + > /// Convert a raw C `struct device` pointer to a `&'a Device`. > /// > /// # Safety > -- > 2.48.1 >
On Thu, Mar 20, 2025 at 08:36:02AM +0000, Alice Ryhl wrote: > On Wed, Mar 19, 2025 at 09:30:26PM +0100, Danilo Krummrich wrote: > > Implement bus_type_raw(), which returns a raw pointer to the device' > > struct bus_type. > > > > This is useful for bus devices, to implement the following trait. > > > > impl TryFrom<&Device> for &pci::Device > > > > With this a caller can try to get the bus specific device from a generic > > device in a safe way. try_from() will only succeed if the generic > > device' bus type pointer matches the pointer of the bus' type. > > > > Signed-off-by: Danilo Krummrich <dakr@kernel.org> > > --- > > rust/kernel/device.rs | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs > > index 76b341441f3f..e2de0efd4a27 100644 > > --- a/rust/kernel/device.rs > > +++ b/rust/kernel/device.rs > > @@ -78,6 +78,13 @@ pub fn parent<'a>(&self) -> Option<&'a Self> { > > } > > } > > > > + /// Returns a raw pointer to the device' bus type. > > + #[expect(unused)] > > + pub(crate) fn bus_type_raw(&self) -> *const bindings::bus_type { > > + // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. > > Is this field immutable? dev->bus is a pointer to a const struct bus_type, yes. > > > + unsafe { (*self.as_raw()).bus } > > + } > > + > > /// Convert a raw C `struct device` pointer to a `&'a Device`. > > /// > > /// # Safety > > -- > > 2.48.1 > >
On Thu, Mar 20, 2025 at 01:00:23PM +0100, Danilo Krummrich wrote: > On Thu, Mar 20, 2025 at 08:36:02AM +0000, Alice Ryhl wrote: > > On Wed, Mar 19, 2025 at 09:30:26PM +0100, Danilo Krummrich wrote: > > > Implement bus_type_raw(), which returns a raw pointer to the device' > > > struct bus_type. > > > > > > This is useful for bus devices, to implement the following trait. > > > > > > impl TryFrom<&Device> for &pci::Device > > > > > > With this a caller can try to get the bus specific device from a generic > > > device in a safe way. try_from() will only succeed if the generic > > > device' bus type pointer matches the pointer of the bus' type. > > > > > > Signed-off-by: Danilo Krummrich <dakr@kernel.org> > > > --- > > > rust/kernel/device.rs | 7 +++++++ > > > 1 file changed, 7 insertions(+) > > > > > > diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs > > > index 76b341441f3f..e2de0efd4a27 100644 > > > --- a/rust/kernel/device.rs > > > +++ b/rust/kernel/device.rs > > > @@ -78,6 +78,13 @@ pub fn parent<'a>(&self) -> Option<&'a Self> { > > > } > > > } > > > > > > + /// Returns a raw pointer to the device' bus type. > > > + #[expect(unused)] > > > + pub(crate) fn bus_type_raw(&self) -> *const bindings::bus_type { > > > + // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. > > > > Is this field immutable? > > dev->bus is a pointer to a const struct bus_type, yes. With that added to the SAFETY comment to justify reading the field is data-race free, you may add: Reviewed-by: Alice Ryhl <aliceryhl@google.com>
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 76b341441f3f..e2de0efd4a27 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -78,6 +78,13 @@ pub fn parent<'a>(&self) -> Option<&'a Self> { } } + /// Returns a raw pointer to the device' bus type. + #[expect(unused)] + pub(crate) fn bus_type_raw(&self) -> *const bindings::bus_type { + // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`. + unsafe { (*self.as_raw()).bus } + } + /// Convert a raw C `struct device` pointer to a `&'a Device`. /// /// # Safety
Implement bus_type_raw(), which returns a raw pointer to the device' struct bus_type. This is useful for bus devices, to implement the following trait. impl TryFrom<&Device> for &pci::Device With this a caller can try to get the bus specific device from a generic device in a safe way. try_from() will only succeed if the generic device' bus type pointer matches the pointer of the bus' type. Signed-off-by: Danilo Krummrich <dakr@kernel.org> --- rust/kernel/device.rs | 7 +++++++ 1 file changed, 7 insertions(+)