Use strong references in context set.

src/context/mod.rs

@@ -104,7 +104,7 @@ pub fn init() {
 
     CONTEXTS
         .write()
-        .insert(ContextRef(Arc::downgrade(&context_lock)));
+        .insert(ContextRef(Arc::clone(&context_lock)));
 
     unsafe {
         let percpu = PercpuBlock::current();
@@ -140,11 +140,16 @@ pub fn current_pid() -> Result<ProcessId> {
     Ok(current().read().pid)
 }
 
-pub struct ContextRef(pub Weak<RwSpinlock<Context>>);
+pub struct ContextRef(pub Arc<RwSpinlock<Context>>);
+impl ContextRef {
+    pub fn upgrade(&self) -> Option<Arc<RwSpinlock<Context>>> {
+        Some(Arc::clone(&self.0))
+    }
+}
 
 impl Ord for ContextRef {
     fn cmp(&self, other: &Self) -> core::cmp::Ordering {
-        Ord::cmp(&self.0.as_ptr(), &other.0.as_ptr())
+        Ord::cmp(&Arc::as_ptr(&self.0), &Arc::as_ptr(&other.0))
     }
 }
 impl PartialOrd for ContextRef {
@@ -175,7 +180,7 @@ pub fn spawn(
 
     CONTEXTS
         .write()
-        .insert(ContextRef(Arc::downgrade(&context_lock)));
+        .insert(ContextRef(Arc::clone(&context_lock)));
 
     process.write().threads.push(Arc::downgrade(&context_lock));
     {

src/context/switch.rs

@@ -131,7 +131,7 @@ pub fn switch() -> SwitchResult {
         for next_context_lock in contexts
             // Include all contexts with IDs greater than the current...
             .range((
-                Bound::Excluded(ContextRef(Arc::downgrade(&prev_context_lock))),
+                Bound::Excluded(ContextRef(Arc::clone(&prev_context_lock))),
                 Bound::Unbounded,
             ))
             .chain(
@@ -139,10 +139,10 @@ pub fn switch() -> SwitchResult {
                     // ... and all contexts with IDs less than the current...
                     .range((
                         Bound::Unbounded,
-                        Bound::Excluded(ContextRef(Arc::downgrade(&prev_context_lock))),
+                        Bound::Excluded(ContextRef(Arc::clone(&prev_context_lock))),
                     )),
             )
-            .filter_map(|r| r.0.upgrade())
+            .filter_map(|r| r.upgrade())
             .chain(Some(Arc::clone(&idle_context)))
         // ... but not the current context, which is already locked
         {

src/scheme/sys/block.rs

@@ -10,7 +10,7 @@ pub fn resource() -> Result<Vec<u8>> {
         let mut rows = Vec::new();
         {
             let contexts = context::contexts();
-            for context_lock in contexts.iter().filter_map(|r| r.0.upgrade()) {
+            for context_lock in contexts.iter().filter_map(|r| r.upgrade()) {
                 let context = context_lock.read();
                 rows.push((
                     context.pid.get(),

src/scheme/sys/context.rs

@@ -27,7 +27,7 @@ pub fn resource() -> Result<Vec<u8>> {
     );
     {
         let contexts = context::contexts();
-        for context_ref in contexts.iter().filter_map(|r| r.0.upgrade()) {
+        for context_ref in contexts.iter().filter_map(|r| r.upgrade()) {
             let context = context_ref.read();
 
             let mut stat_string = String::new();

src/scheme/sys/iostat.rs

@@ -9,7 +9,7 @@ pub fn resource() -> Result<Vec<u8>> {
         let mut rows = Vec::new();
         {
             let contexts = context::contexts();
-            for context_ref in contexts.iter().filter_map(|r| r.0.upgrade()) {
+            for context_ref in contexts.iter().filter_map(|r| r.upgrade()) {
                 let context = context_ref.read();
                 rows.push((
                     context.pid,

src/scheme/sys/syscall.rs

@@ -10,7 +10,7 @@ pub fn resource() -> Result<Vec<u8>> {
         let mut rows = Vec::new();
         {
             let contexts = context::contexts();
-            for context_ref in contexts.iter().filter_map(|r| r.0.upgrade()) {
+            for context_ref in contexts.iter().filter_map(|r| r.upgrade()) {
                 let context = context_ref.read();
                 rows.push((
                     context.pid.get(),