[PATCH] thread management - take three

you have applied my independent-pointer patch already, but i think your
CLEARTID variant is the most elegant solution: it reuses a clone argument,
thus reduces the number of arguments and it's also a nice conceptual pair
to the existing SETTID call. And the TID field can be used as a 'usage'
field as well, because the TID (PID) can never be 0, reducing the number
of fields in the TCB. And we can change the userspace locking code to use
the TID field no problem.

1 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 767d1b7bd0ec..5713927c300a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -47,8 +47,8 @@ struct exec_domain;
 #define CLONE_SYSVSEM	0x00040000	/* share system V SEM_UNDO semantics */
 #define CLONE_SETTLS	0x00080000	/* create a new TLS for the child */
 #define CLONE_SETTID	0x00100000	/* write the TID back to userspace */
-#define CLONE_DETACHED	0x00200000	/* parent wants no child-exit signal */
-#define CLONE_RELEASE_VM 0x00400000	/* release the userspace VM */
+#define CLONE_CLEARTID	0x00200000	/* clear the userspace TID */
+#define CLONE_DETACHED	0x00400000	/* parent wants no child-exit signal */
 
 #define CLONE_SIGNAL	(CLONE_SIGHAND | CLONE_THREAD)
 
@@ -307,7 +307,7 @@ struct task_struct {
 
 	wait_queue_head_t wait_chldexit;	/* for wait4() */
 	struct completion *vfork_done;		/* for vfork() */
-	long *user_vm_lock;			/* for CLONE_RELEASE_VM */
+	long *user_tid;				/* for CLONE_CLEARTID */
 
 	unsigned long rt_priority;
 	unsigned long it_real_value, it_prof_value, it_virt_value;