Changeset 62502cc4 for libcfa/src

Timestamp:

Aug 13, 2020, 1:19:20 PM (5 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

badd22f

Parents:

0240cd69

Message:

Fixed deadlock where threads could acquire the central scheduler lock for writing while preemption was enabled, leading to any attempt at running any thread to deadlock.
Also added runtime checks to catch new code which could forget to disable interrupts

Location:

libcfa/src/concurrency

Files:

• kernel/startup.cfa (modified) (2 diffs)
• ready_queue.cfa (modified) (3 diffs)

libcfa/src/concurrency/kernel/startup.cfa

@@ -516 +516 @@
         ( this.terminated ){ 0 };
         ( this.runner ){};
-        init( this, name, _cltr );
+
+        disable_interrupts();
+                init( this, name, _cltr );
+        enable_interrupts( __cfaabi_dbg_ctx );
 
         __cfadbg_print_safe(runtime_core, "Kernel : Starting core %p\n", &this);
@@ -540 +543 @@
         free( this.stack );
 
-        deinit( this );
+        disable_interrupts();
+                deinit( this );
+        enable_interrupts( __cfaabi_dbg_ctx );
 }
 

libcfa/src/concurrency/ready_queue.cfa

@@ -150 +150 @@
 //  queues or removing them.
 uint_fast32_t ready_mutate_lock( void ) with(*__scheduler_lock) {
+        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
+
         // Step 1 : lock global lock
         // It is needed to avoid processors that register mid Critical-Section
@@ -164 +166 @@
         }
 
+        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
         return s;
 }
 
 void ready_mutate_unlock( uint_fast32_t last_s ) with(*__scheduler_lock) {
+        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
+
         // Step 1 : release local locks
         // This must be done while the global lock is held to avoid
@@ -182 +187 @@
         /*paranoid*/ assert(true == lock);
         __atomic_store_n(&lock, (bool)false, __ATOMIC_RELEASE);
+
+        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
 }