uefi: Wrap ScsiPassThruProtocol in UnsafeCell

See abdd6c4 ("uefi: Wrap AtaPassThruProtocol in UnsafeCell") for details on
why this change is needed.

Author: nicholasbishop

uefi/src/proto/scsi/pass_thru.rs

@@ -8,6 +8,7 @@ use crate::mem::{AlignedBuffer, PoolAllocation};
 use crate::proto::device_path::PoolDevicePathNode;
 use crate::proto::unsafe_protocol;
 use core::alloc::LayoutError;
+use core::cell::UnsafeCell;
 use core::ptr::{self, NonNull};
 use uefi_raw::Status;
 use uefi_raw::protocol::device_path::DevicePathProtocol;
@@ -42,7 +43,7 @@ impl Default for ScsiTargetLun {
 #[derive(Debug)]
 #[repr(transparent)]
 #[unsafe_protocol(ExtScsiPassThruProtocol::GUID)]
-pub struct ExtScsiPassThru(ExtScsiPassThruProtocol);
+pub struct ExtScsiPassThru(UnsafeCell<ExtScsiPassThruProtocol>);
 
 impl ExtScsiPassThru {
     /// Retrieves the mode structure for the Extended SCSI Pass Thru protocol.
@@ -51,7 +52,7 @@ impl ExtScsiPassThru {
     /// The [`ExtScsiPassThruMode`] structure containing configuration details of the protocol.
     #[must_use]
     pub fn mode(&self) -> ExtScsiPassThruMode {
-        let mut mode = unsafe { (*self.0.passthru_mode).clone() };
+        let mut mode = unsafe { (*(*self.0.get()).passthru_mode).clone() };
         mode.io_align = mode.io_align.max(1); // 0 and 1 is the same, says UEFI spec
         mode
     }
@@ -113,7 +114,7 @@ impl ExtScsiPassThru {
     /// - [`Status::DEVICE_ERROR`] A device error occurred while attempting to reset the SCSI channel.
     /// - [`Status::TIMEOUT`] A timeout occurred while attempting to reset the SCSI channel.
     pub fn reset_channel(&mut self) -> crate::Result<()> {
-        unsafe { (self.0.reset_channel)(&mut self.0).to_result() }
+        unsafe { ((*self.0.get()).reset_channel)(self.0.get()).to_result() }
     }
 }
 
@@ -126,14 +127,10 @@ impl ExtScsiPassThru {
 /// You have to probe for availability before doing anything meaningful with it.
 #[derive(Clone, Debug)]
 pub struct ScsiDevice<'a> {
-    proto: &'a ExtScsiPassThruProtocol,
+    proto: &'a UnsafeCell<ExtScsiPassThruProtocol>,
     target_lun: ScsiTargetLun,
 }
 impl ScsiDevice<'_> {
-    const fn proto_mut(&mut self) -> *mut ExtScsiPassThruProtocol {
-        ptr::from_ref(self.proto).cast_mut()
-    }
-
     /// Returns the SCSI target address of the potential device.
     #[must_use]
     pub const fn target(&self) -> &ScsiTarget {
@@ -153,8 +150,8 @@ impl ScsiDevice<'_> {
     pub fn path_node(&self) -> crate::Result<PoolDevicePathNode> {
         unsafe {
             let mut path_ptr: *const DevicePathProtocol = ptr::null();
-            (self.proto.build_device_path)(
-                self.proto,
+            ((*self.proto.get()).build_device_path)(
+                self.proto.get(),
                 self.target().as_ptr(),
                 self.lun(),
                 &mut path_ptr,
@@ -185,8 +182,12 @@ impl ScsiDevice<'_> {
     ///   by `Target` and `Lun`.
     pub fn reset(&mut self) -> crate::Result<()> {
         unsafe {
-            (self.proto.reset_target_lun)(self.proto_mut(), self.target_lun.0.as_ptr(), self.lun())
-                .to_result()
+            ((*self.proto.get()).reset_target_lun)(
+                self.proto.get(),
+                self.target_lun.0.as_ptr(),
+                self.lun(),
+            )
+            .to_result()
         }
     }
 
@@ -223,8 +224,8 @@ impl ScsiDevice<'_> {
         mut scsi_req: ScsiRequest<'req>,
     ) -> crate::Result<ScsiResponse<'req>> {
         unsafe {
-            (self.proto.pass_thru)(
-                self.proto_mut(),
+            ((*self.proto.get()).pass_thru)(
+                self.proto.get(),
                 self.target_lun.0.as_ptr(),
                 self.target_lun.1,
                 &mut scsi_req.packet,
@@ -238,7 +239,7 @@ impl ScsiDevice<'_> {
 /// An iterator over SCSI devices available on the channel.
 #[derive(Debug)]
 pub struct ScsiTargetLunIterator<'a> {
-    proto: &'a ExtScsiPassThruProtocol,
+    proto: &'a UnsafeCell<ExtScsiPassThruProtocol>,
     prev: ScsiTargetLun,
 }
 impl<'a> Iterator for ScsiTargetLunIterator<'a> {
@@ -248,8 +249,13 @@ impl<'a> Iterator for ScsiTargetLunIterator<'a> {
         // get_next_target_lun() takes the target as a double ptr, meaning that the spec allows
         // the implementation to return us a new buffer (most impls don't actually seem to do though)
         let mut target: *mut u8 = self.prev.0.as_mut_ptr();
-        let result =
-            unsafe { (self.proto.get_next_target_lun)(self.proto, &mut target, &mut self.prev.1) };
+        let result = unsafe {
+            ((*self.proto.get()).get_next_target_lun)(
+                self.proto.get(),
+                &mut target,
+                &mut self.prev.1,
+            )
+        };
         if target != self.prev.0.as_mut_ptr() {
             // impl has returned us a new pointer instead of writing in our buffer, copy back
             unsafe {