Downgrade locks to read

src/context/context.rs

@@ -1004,7 +1004,7 @@ pub fn bulk_add_fds(
         return Ok(0);
     }
     let current_lock = context::current();
-    let mut current = current_lock.write(token.token());
+    let mut current = current_lock.read(token.token());
     let (current, mut token) = current.token_split();
 
     let files: Vec<FileDescriptor> = descriptions
@@ -1048,7 +1048,7 @@ pub fn bulk_insert_fds(
         .read_usize()?;
 
     let current_lock = context::current();
-    let mut current = current_lock.write(token.token());
+    let mut current = current_lock.read(token.token());
     let (current, mut token) = current.token_split();
 
     if first_fd == usize::MAX {

src/context/memory.rs

@@ -65,7 +65,7 @@ impl UnmapResult {
         };
 
         let (scheme_id, number) = {
-            let desc = description.write(token.token());
+            let desc = description.read(token.token());
             (desc.scheme, desc.number)
         };
 

src/scheme/acpi.rs

@@ -181,8 +181,8 @@ impl KernelScheme for AcpiScheme {
         Ok(OpenResult::SchemeLocal(fd, int_flags))
     }
     fn fsize(&self, id: usize, token: &mut CleanLockToken) -> Result<u64> {
-        let mut handles = HANDLES.write(token.token());
-        let handle = handles.get_mut(id)?;
+        let mut handles = HANDLES.read(token.token());
+        let handle = handles.get(id)?;
 
         if handle.stat {
             return Err(Error::new(EBADF));

src/scheme/proc.rs

@@ -633,8 +633,8 @@ impl KernelScheme for ProcScheme {
     ) -> Result<usize> {
         // TODO: simplify
         let handle = {
-            let mut handles = HANDLES.write(token.token());
-            let handle = handles.get_mut(&id).ok_or(Error::new(EBADF))?;
+            let mut handles = HANDLES.read(token.token());
+            let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
             handle.clone()
         };
 
@@ -667,8 +667,8 @@ impl KernelScheme for ProcScheme {
 
         // Don't hold a global lock during the context switch later on
         let handle = {
-            let mut handles = HANDLES.write(token.token());
-            let handle = handles.get_mut(&id).ok_or(Error::new(EBADF))?;
+            let mut handles = HANDLES.read(token.token());
+            let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
             handle.clone()
         };
 
@@ -696,8 +696,8 @@ impl KernelScheme for ProcScheme {
     }
 
     fn fsize(&self, id: usize, token: &mut CleanLockToken) -> Result<u64> {
-        let mut handles = HANDLES.write(token.token());
-        let handle = handles.get_mut(&id).ok_or(Error::new(EBADF))?;
+        let mut handles = HANDLES.read(token.token());
+        let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
 
         handle.fsize()
     }

src/scheme/sys/mod.rs

@@ -165,7 +165,7 @@ impl KernelScheme for SysScheme {
         if matches!(kind, Kind::Wr(_)) {
             return Ok(0);
         }
-        let is_data_none = data_lock.write(token.token()).is_none();
+        let is_data_none = data_lock.read(token.token()).is_none();
         if is_data_none {
             let new_data = kind.generate_data(token)?;
             let mut data_guard = data_lock.write(token.token());
@@ -218,7 +218,7 @@ impl KernelScheme for SysScheme {
                 _ => return Err(Error::new(EBADF)),
             }
         };
-        let is_data_none = data_lock.write(token.token()).is_none();
+        let is_data_none = data_lock.read(token.token()).is_none();
         if is_data_none {
             let new_data = kind.generate_data(token)?;
             let mut data_guard = data_lock.write(token.token());
@@ -296,7 +296,7 @@ impl KernelScheme for SysScheme {
             }
         };
         let stat = if let Some((kind, data_lock)) = stat_base {
-            let is_data_none = data_lock.write(token.token()).is_none();
+            let is_data_none = data_lock.read(token.token()).is_none();
             if is_data_none {
                 let new_data = kind.generate_data(token)?;
                 let mut data_guard = data_lock.write(token.token());

src/syscall/fs.rs

@@ -441,7 +441,7 @@ pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize, token: &mut CleanLockToken)
     .ok_or(Error::new(EBADF))?;
 
     let (scheme_id, number, flags) = {
-        let desc = file.description.write(token.token());
+        let desc = file.description.read(token.token());
         (desc.scheme, desc.number, desc.flags)
     };