rust: device: change the from_raw() function

The function Device::from_raw() increments a refcount by a call to bindings::get_device(ptr). This can be confused because usually from_raw() functions don't increment a refcount.
Hence, rename Device::from_raw() to avoid confuion with other "from_raw" semantics.

The new name of function should be "get_device" to be consistent with the function get_device() already exist in .c files.

This function body also changed, because the into() will convert the &'a Device into ARef<Device> and also call inc_ref from the AlwaysRefCounted trait implemented for Device.

Signed-off-by Guilherme Giacomo Simoes <[email protected]>

---

 rust/kernel/device.rs   | 15 +++------------
 rust/kernel/firmware.rs |  2 +-
 2 files changed, 4 insertions(+), 13 deletions(-)

rust/kernel/device.rs +3 -12

index 851018eef885..c8199ee079ef 100644
@@ -51,18 +51,9 @@ impl Device {
     ///
     /// It must also be ensured that `bindings::device::release` can be called from any thread.
     /// While not officially documented, this should be the case for any `struct device`.
-    pub unsafe fn from_raw(ptr: *mut bindings::device) -> ARef<Self> {
-        // SAFETY: By the safety requirements, ptr is valid.
-        // Initially increase the reference count by one to compensate for the final decrement once
-        // this newly created `ARef<Device>` instance is dropped.
-        unsafe { bindings::get_device(ptr) };
-
-        // CAST: `Self` is a `repr(transparent)` wrapper around `bindings::device`.
-        let ptr = ptr.cast::<Self>();
-
-        // SAFETY: `ptr` is valid by the safety requirements of this function. By the above call to
-        // `bindings::get_device` we also own a reference to the underlying `struct device`.
-        unsafe { ARef::from_raw(ptr::NonNull::new_unchecked(ptr)) }
+    pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef<Self> {
+        // SAFETY: By the safety requirements ptr is valid
+        unsafe { Self::as_ref(ptr) }.into()
     }
 
     /// Obtain the raw `struct device *`.

rust/kernel/firmware.rs +1 -1

index dee5b4b18aec..13a374a5cdb7 100644
@@ -44,7 +44,7 @@ fn request_nowarn() -> Self {
 ///
 /// # fn no_run() -> Result<(), Error> {
 /// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
-/// # let dev = unsafe { Device::from_raw(core::ptr::null_mut()) };
+/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
 ///
 /// let fw = Firmware::request(c_str!("path/to/firmware.bin"), &dev)?;
 /// let blob = fw.data();

Signature · 8 lines

The motivation from this change was will discussion in:
https://rust-for-linux.zulipchat.com/#narrow/stream/291566-Library/topic/Inconsistency.20of.20.60from_raw.60.2E

I would like to thanks for Greg <[email protected]>, Danilo
<[email protected]> and Alice <[email protected]> for help me with this
patch.

2.46.2

The function Device::from_raw() increments a refcount by a call to bindings::get_device(ptr). This can be confused because usually from_raw() functions don't increment a refcount.
Hence, rename Device::from_raw() to avoid confuion with other "from_raw" semantics.

The new name of function should be "get_device" to be consistent with the function get_device() already exist in .c files.

This function body also changed, because the into() will convert the &'a Device into ARef<Device> and also call inc_ref from the AlwaysRefCounted trait implemented for Device.

Signed-off-by Guilherme Giacomo Simoes <[email protected]>

---
 rust/kernel/device.rs   | 15 +++------------
 rust/kernel/firmware.rs |  2 +-
 2 files changed, 4 insertions(+), 13 deletions(-)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree.

You are receiving this message because of the following common error(s) as indicated below:

- This looks like a new version of a previously submitted patch, but you did not list below the --- line any changes from the previous version. Please read the section entitled "The canonical patch format" in the kernel file, Documentation/process/submitting-patches.rst for what needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about how to resolve this issue, please feel free to respond to this email and Greg will reply once he has dug out from the pending patches received from other developers.

thanks,

greg k-h's patch email bot

Quoted 25 lines · Greg KH

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree.

You are receiving this message because of the following common error(s) as indicated below:

- This looks like a new version of a previously submitted patch, but you did not list below the --- line any changes from the previous version. Please read the section entitled "The canonical patch format" in the kernel file, Documentation/process/submitting-patches.rst for what needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about how to resolve this issue, please feel free to respond to this email and Greg will reply once he has dug out from the pending patches received from other developers.

Quoted 3 lines

thanks,

greg k-h's patch email bot

How I created a new patch, and not another version of previous patch, I really don't incremental changes after --- line