- Create a new lock, umtx_lock, for use instead of the proc lock for

   protecting the umtx queues.  We can't use the proc lock because we need
   to hold the lock across calls to casuptr, which can fault.

Approved by:	re

1 files changed, 13 insertions, 6 deletions

diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
index 8c01669..bd0f524 100644
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -39,6 +39,13 @@
 #include <sys/thr.h>
 #include <sys/umtx.h>
 
+#define	UMTX_LOCK()	mtx_lock(&umtx_lock);
+#define	UMTX_UNLOCK()	mtx_unlock(&umtx_lock);
+
+struct mtx umtx_lock;
+
+MTX_SYSINIT(umtx, &umtx_lock, "User-land mutex lock", MTX_DEF);
+
 int
 _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
     /* struct umtx *umtx */
@@ -57,7 +64,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
 	 */
 	umtx = uap->umtx;	
 
-	PROC_LOCK(td->td_proc);
+	UMTX_LOCK();
 
 	for (;;) {
 		/*
@@ -103,7 +110,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
 	}
 
 	/*
-	 * We are now protected from further races via the proc lock.
+	 * We are now protected from further races via umtx_lock.
 	 * If userland messes with their mutex without using cmpset
 	 * they will deadlock themselves but they will still be
 	 * killable via signals.
@@ -146,7 +153,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
 		 * used to maintain proper ordering.
 		 */
 
-		error = msleep(&td->td_umtx, &td->td_proc->p_mtx,
+		error = msleep(&td->td_umtx, &umtx_lock,
 		    td->td_priority | PCATCH, "umtx", 0);
 
 		/*
@@ -171,7 +178,7 @@ _umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
 	}
 
 out:
-	PROC_UNLOCK(td->td_proc);
+	UMTX_UNLOCK();
 
 	return (error);
 }
@@ -190,7 +197,7 @@ _umtx_unlock(struct thread *td, struct _umtx_unlock_args *uap)
 	error = 0;
 	umtx = uap->umtx;
 
-	PROC_LOCK(td->td_proc);
+	UMTX_LOCK();
 
 	/*
 	 * Make sure we own this mtx.
@@ -300,7 +307,7 @@ _umtx_unlock(struct thread *td, struct _umtx_unlock_args *uap)
 	wakeup(&td0->td_umtx);
 
 out:
-	PROC_UNLOCK(td->td_proc);
+	UMTX_UNLOCK();
 
 	return (error);
 }