Replace turnstile with sleepqueue in mutex implementation

* remove turnstile implementation
* adjust debugging tools to support new mutex implementation

debug/mutex.py

@@ -6,7 +6,7 @@
 
 
 def get_mutex_owner(mtx):
-    state = mtx['mtx_state']
+    state = mtx['m_owner']
     td_pointer = gdb.lookup_type('struct thread').pointer()
     owner = state.cast(td_pointer)
     if owner:
@@ -16,12 +16,9 @@ def get_mutex_owner(mtx):
 
 
 def get_threads_blocked_on_mutex(mtx):
-    ts = mtx['turnstile']
-    return map(lambda t: t['td_name'].string(), tailq.collect_values(ts['td_queue'], 'td_lock'))
-
-
-def pretty_list_of_string(lst):
-    return "[" + ", ".join(lst) + "]"
+    sq = gdb.parse_and_eval("sleepq_lookup((void *)%d)" % mtx.address)
+    return map(lambda n: n.string(),
+               tailq.collect_values(sq['sq_blocked'], 'td_name'))
 
 
 class MutexPrettyPrinter():
@@ -30,14 +27,10 @@ def __init__(self, val):
         self.val = val
 
     def to_string(self):
-        res = []
-        if self.val['mtx_state'] == 0:
+        if self.val['m_owner'] == 0:
             return "Mutex unowned"
-        else:
-            res.append("Owner = " + str(get_mutex_owner(self.val)))
-            res.append("Waiting for access = " +
-                       pretty_list_of_string(get_threads_blocked_on_mutex(self.val)))
-        return "\n".join(res)
+        return "{owner = %s, blocked = %s}" % (
+            get_mutex_owner(self.val), get_threads_blocked_on_mutex(self.val))
 
     def display_hint(self):
         return 'map'

include/common.h

@@ -83,17 +83,18 @@ noreturn void thread_exit();
     thread_exit();                                                             \
   })
 
+#ifdef DEBUG
 #define log(FMT, ...)                                                          \
   __extension__(                                                               \
     { kprintf("[%s:%d] " FMT "\n", __FILE__, __LINE__, ##__VA_ARGS__); })
 
-#ifdef DEBUG
 #define assert(EXPR)                                                           \
   __extension__({                                                              \
     if (!(EXPR))                                                               \
       panic("Assertion '" __STRING(EXPR) "' failed!");                         \
   })
 #else
+#define log(...)
 #define assert(expr)
 #endif
 

include/mutex.h

@@ -2,7 +2,6 @@
 #define _SYS_MUTEX_H_
 
 #include <stdbool.h>
-#include <turnstile.h>
 
 typedef struct thread thread_t;
 
@@ -13,7 +12,6 @@ typedef struct mtx {
   volatile thread_t *m_owner; /* stores address of the owner */
   volatile unsigned m_count; /* Counter for recursive mutexes */
   unsigned m_type;           /* Normal or recursive mutex */
-  turnstile_t m_turnstile;   /* FIFO Queue for blocked threads */
 } mtx_t;
 
 /* Initializes mutex. Note that EVERY mutex has to be initialized
@@ -24,7 +22,7 @@ void mtx_init(mtx_t *m, unsigned type);
 bool mtx_owned(mtx_t *mtx);
 
 /* Locks the mutex, if the mutex is already owned by someone,
- * then this blocks on turnstile, otherwise it takes the mutex. */
+ * then this blocks on sleepqueue, otherwise it takes the mutex. */
 void mtx_lock(mtx_t *m);
 
 /* Unlocks the mutex. If some thread blocked for the mutex,

include/thread.h

@@ -22,9 +22,8 @@ typedef struct thread {
   TAILQ_ENTRY(thread) td_all;    /* a link on all threads list */
   TAILQ_ENTRY(thread) td_runq;   /* a link on run queue */
   TAILQ_ENTRY(thread) td_sleepq; /* a link on sleep queue */
-  TAILQ_ENTRY(thread) td_lock;   /* a link on turnstile */
   char *td_name;
-  tid_t td_tid; /* Thread ID*/
+  tid_t td_tid;
   /* thread state */
   enum { TDS_INACTIVE = 0x0, TDS_WAITING, TDS_READY, TDS_RUNNING } td_state;
   uint32_t td_flags;           /* TDF_* flags */

sys/Makefile

@@ -25,7 +25,6 @@ SOURCES_C  = \
 	sync.c \
 	sysent.c \
 	thread.c \
-	turnstile.c \
 	uio.c \
 	vfs.c \
 	vfs_syscalls.c \

sys/mutex.c

@@ -14,7 +14,6 @@ void mtx_init(mtx_t *m, unsigned type) {
   m->m_owner = NULL;
   m->m_count = 0;
   m->m_type = type;
-  turnstile_init(&m->m_turnstile);
 }
 
 void mtx_lock(mtx_t *m) {
@@ -26,7 +25,7 @@ void mtx_lock(mtx_t *m) {
 
   critical_enter();
   while (m->m_owner != NULL)
-    turnstile_wait(&m->m_turnstile);
+    sleepq_wait(&m->m_owner, NULL);
   m->m_owner = thread_self();
   critical_leave();
 }
@@ -41,6 +40,6 @@ void mtx_unlock(mtx_t *m) {
 
   critical_enter();
   m->m_owner = NULL;
-  turnstile_signal(&m->m_turnstile);
+  sleepq_signal(&m->m_owner);
   critical_leave();
 }

sys/sleepq.c

@@ -1,3 +1,4 @@
+#undef DEBUG
 #include <common.h>
 #include <queue.h>
 #include <stdc.h>