Put an end to priority inversion in the ata driver. Gave up trying to have fully atomic dual use mutexes so just replaced the ata driver locking with spins. Maybe I'll have better luck later. Things should run smoothly with database updates and such happening in the background.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12688 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 22 insertions, 2 deletions

diff --git a/firmware/export/kernel.h b/firmware/export/kernel.h
index ec8aa28a08..495e558175 100644
--- a/firmware/export/kernel.h
+++ b/firmware/export/kernel.h
@@ -83,10 +83,14 @@ struct event_queue
 #endif
 };
 
+#define MTX_UNOWNED         0x00000000
+#define MTX_BLOCKED_WAITER  0x00000001
+#define MTX_SPIN_WAITER     0x00010001
+#define MTX_SPIN_OWNER      0x00020001
 struct mutex
 {
+    uint32_t locked;
     struct thread_entry *thread;
-    bool locked;
 };
 
 /* global tick variable */
@@ -126,8 +130,12 @@ extern void queue_remove_from_head(struct event_queue *q, long id);
 extern int queue_broadcast(long id, intptr_t data);
 
 extern void mutex_init(struct mutex *m);
+static inline void spinlock_init(struct mutex *m)
+{ mutex_init(m); } /* Same thing for now */
 extern void mutex_lock(struct mutex *m);
 extern void mutex_unlock(struct mutex *m);
+extern void spinlock_lock(struct mutex *m);
+extern void spinlock_unlock(struct mutex *m);
 extern void tick_start(unsigned int interval_in_ms);
 
 #define IS_SYSEVENT(ev) ((ev & SYS_EVENT) == SYS_EVENT)
diff --git a/firmware/export/thread.h b/firmware/export/thread.h
index 3a979722b9..7a9414c79f 100644
--- a/firmware/export/thread.h
+++ b/firmware/export/thread.h
@@ -105,6 +105,7 @@ struct thread_entry {
     unsigned short stack_size;
 #ifdef HAVE_PRIORITY_SCHEDULING
     unsigned short priority;
+    unsigned long priority_x;
     long last_run;
 #endif
     struct thread_entry *next, *prev;
@@ -114,6 +115,10 @@ struct core_entry {
     struct thread_entry threads[MAXTHREADS];
     struct thread_entry *running;
     struct thread_entry *sleeping;
+#ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
+    int switch_to_irq_level;
+    #define STAY_IRQ_LEVEL -1
+#endif
 };
 
 #ifdef HAVE_PRIORITY_SCHEDULING
@@ -149,7 +154,14 @@ void wakeup_thread(struct thread_entry **thread);
 #ifdef HAVE_PRIORITY_SCHEDULING
 int thread_set_priority(struct thread_entry *thread, int priority);
 int  thread_get_priority(struct thread_entry *thread);
-#endif
+/* Yield that guarantees thread execution once per round regardless of
+   thread's scheduler priority - basically a transient realtime boost
+   without altering the scheduler's thread precedence. */
+void priority_yield(void);
+#else
+static inline void priority_yield(void)
+    { yield(); }
+#endif /* HAVE_PRIORITY_SCHEDULING */
 struct thread_entry * thread_get_current(void);
 void init_threads(void);
 int thread_stack_usage(const struct thread_entry *thread);