rust: pci: require Send for Driver trait implementers

The instance of Self, returned and created by Driver::probe() is
dropped in the bus' remove() callback.

Request implementers of the Driver trait to implement Send, since the
remove() callback is not guaranteed to run from the same thread as
probe().

Fixes: 1bd8b6b ("rust: pci: add basic PCI device / driver abstractions")
Cc: stable <stable@kernel.org>
Reported-by: Alice Ryhl <aliceryhl@google.com>
Closes: https://lore.kernel.org/lkml/Z9rDxOJ2V2bPjj5i@google.com/
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20250319145350.69543-1-dakr@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Danilo Krummrich

rust/kernel/pci.rs

@@ -222,7 +222,7 @@ macro_rules! pci_device_table {
 ///```
 /// Drivers must implement this trait in order to get a PCI driver registered. Please refer to the
 /// `Adapter` documentation for an example.
-pub trait Driver {
+pub trait Driver: Send {
     /// The type holding information about each device id supported by the driver.
     ///
     /// TODO: Use associated_type_defaults once stabilized: