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Subject[patch] threading enhancements, tid-2.5.48-A1

here's an update to the patch, Ulrich noticed that the x86 register
parameters were incorrect, the correct use is %edx for the parent pointer,
%edi for the child pointer.

Ingo

--- linux/arch/i386/kernel/smpboot.c.orig 2002-11-20 09:19:38.000000000 +0100
+++ linux/arch/i386/kernel/smpboot.c 2002-11-20 09:19:59.000000000 +0100
@@ -499,7 +499,7 @@
* don't care about the eip and regs settings since
* we'll never reschedule the forked task.
*/
- return do_fork(CLONE_VM|CLONE_IDLETASK, 0, &regs, 0, NULL);
+ return do_fork(CLONE_VM|CLONE_IDLETASK, 0, &regs, 0, NULL, NULL);
}

/* which physical APIC ID maps to which logical CPU number */
--- linux/arch/i386/kernel/process.c.orig 2002-11-20 09:19:38.000000000 +0100
+++ linux/arch/i386/kernel/process.c 2002-11-20 10:33:43.000000000 +0100
@@ -226,7 +226,7 @@
regs.eflags = 0x286;

/* Ok, create the new process.. */
- p = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL);
+ p = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
return IS_ERR(p) ? PTR_ERR(p) : p->pid;
}

@@ -288,7 +288,7 @@
struct_cpy(childregs, regs);
childregs->eax = 0;
childregs->esp = esp;
- p->user_tid = NULL;
+ p->set_child_tid = p->clear_child_tid = NULL;

p->thread.esp = (unsigned long) childregs;
p->thread.esp0 = (unsigned long) (childregs+1);
@@ -503,7 +503,7 @@
{
struct task_struct *p;

- p = do_fork(SIGCHLD, regs.esp, &regs, 0, NULL);
+ p = do_fork(SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
return IS_ERR(p) ? PTR_ERR(p) : p->pid;
}

@@ -512,14 +512,15 @@
struct task_struct *p;
unsigned long clone_flags;
unsigned long newsp;
- int *user_tid;
+ int *parent_tidptr, *child_tidptr;

clone_flags = regs.ebx;
newsp = regs.ecx;
- user_tid = (int *)regs.edx;
+ parent_tidptr = (int *)regs.edx;
+ child_tidptr = (int *)regs.edi;
if (!newsp)
newsp = regs.esp;
- p = do_fork(clone_flags & ~CLONE_IDLETASK, newsp, &regs, 0, user_tid);
+ p = do_fork(clone_flags & ~CLONE_IDLETASK, newsp, &regs, 0, parent_tidptr, child_tidptr);
return IS_ERR(p) ? PTR_ERR(p) : p->pid;
}

@@ -537,7 +538,7 @@
{
struct task_struct *p;

- p = do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, &regs, 0, NULL);
+ p = do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
return IS_ERR(p) ? PTR_ERR(p) : p->pid;
}

--- linux/arch/i386/kernel/entry.S.orig 2002-11-20 09:25:32.000000000 +0100
+++ linux/arch/i386/kernel/entry.S 2002-11-20 09:25:37.000000000 +0100
@@ -193,10 +193,8 @@


ENTRY(ret_from_fork)
-#if CONFIG_SMP || CONFIG_PREEMPT
# NOTE: this function takes a parameter but it's unused on x86.
call schedule_tail
-#endif
GET_THREAD_INFO(%ebx)
jmp syscall_exit

--- linux/include/linux/sched.h.orig 2002-11-20 09:18:47.000000000 +0100
+++ linux/include/linux/sched.h 2002-11-20 09:25:19.000000000 +0100
@@ -46,10 +46,11 @@
#define CLONE_NEWNS 0x00020000 /* New namespace group? */
#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_CLEARTID 0x00200000 /* clear the userspace TID */
-#define CLONE_DETACHED 0x00400000 /* parent wants no child-exit signal */
-#define CLONE_UNTRACED 0x00800000 /* set if the tracing process can't force CLONE_PTRACE on this clone */
+#define CLONE_PARENT_SETTID 0x00100000 /* set the TID in the parent */
+#define CLONE_CHILD_CLEARTID 0x00200000 /* clear the TID in the child */
+#define CLONE_DETACHED 0x00400000 /* parent wants no child-exit signal */
+#define CLONE_UNTRACED 0x00800000 /* set if the tracing process can't force CLONE_PTRACE on this clone */
+#define CLONE_CHILD_SETTID 0x01000000 /* set the TID in the child */

/*
* List of flags we want to share for kernel threads,
@@ -332,7 +333,8 @@

wait_queue_head_t wait_chldexit; /* for wait4() */
struct completion *vfork_done; /* for vfork() */
- int *user_tid; /* for CLONE_CLEARTID */
+ int *set_child_tid; /* CLONE_CHILD_SETTID */
+ int *clear_child_tid; /* CLONE_CHILD_CLEARTID */

unsigned long rt_priority;
unsigned long it_real_value, it_prof_value, it_virt_value;
@@ -615,7 +617,7 @@
extern task_t *child_reaper;

extern int do_execve(char *, char **, char **, struct pt_regs *);
-extern struct task_struct *do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int *);
+extern struct task_struct *do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int *, int *);

#ifdef CONFIG_SMP
extern void wait_task_inactive(task_t * p);
--- linux/kernel/fork.c.orig 2002-11-20 09:19:38.000000000 +0100
+++ linux/kernel/fork.c 2002-11-20 09:27:12.000000000 +0100
@@ -408,16 +408,16 @@
tsk->vfork_done = NULL;
complete(vfork_done);
}
- if (tsk->user_tid) {
- int * user_tid = tsk->user_tid;
- tsk->user_tid = NULL;
+ if (tsk->clear_child_tid) {
+ int * tidptr = tsk->clear_child_tid;
+ tsk->clear_child_tid = NULL;

/*
* We dont check the error code - if userspace has
* not set up a proper pointer then tough luck.
*/
- put_user(0, user_tid);
- sys_futex((unsigned long)user_tid, FUTEX_WAKE, 1, NULL);
+ put_user(0, tidptr);
+ sys_futex((unsigned long)tidptr, FUTEX_WAKE, 1, NULL);
}
}

@@ -680,9 +680,9 @@
p->flags = new_flags;
}

-asmlinkage int sys_set_tid_address(int *user_tid)
+asmlinkage int sys_set_tid_address(int *tidptr)
{
- current->user_tid = user_tid;
+ current->clear_child_tid = tidptr;

return current->pid;
}
@@ -699,7 +699,8 @@
unsigned long stack_start,
struct pt_regs *regs,
unsigned long stack_size,
- int *user_tid)
+ int *parent_tidptr,
+ int *child_tidptr)
{
int retval;
struct task_struct *p = NULL;
@@ -823,19 +824,18 @@
retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
if (retval)
goto bad_fork_cleanup_namespace;
- /*
- * Notify the child of the TID?
- */
+
retval = -EFAULT;
- if (clone_flags & CLONE_SETTID)
- if (put_user(p->pid, user_tid))
+ if (clone_flags & CLONE_PARENT_SETTID)
+ if (put_user(p->pid, parent_tidptr))
goto bad_fork_cleanup_namespace;
-
+ if (clone_flags & CLONE_CHILD_SETTID)
+ p->set_child_tid = child_tidptr;
/*
- * Does the userspace VM want the TID cleared on mm_release()?
+ * Clear TID on mm_release()?
*/
- if (clone_flags & CLONE_CLEARTID)
- p->user_tid = user_tid;
+ if (clone_flags & CLONE_CHILD_CLEARTID)
+ p->clear_child_tid = child_tidptr;

/*
* Syscall tracing should be turned off in the child regardless
@@ -1004,7 +1004,8 @@
unsigned long stack_start,
struct pt_regs *regs,
unsigned long stack_size,
- int *user_tid)
+ int *parent_tidptr,
+ int *child_tidptr)
{
struct task_struct *p;
int trace = 0;
@@ -1015,7 +1016,7 @@
clone_flags |= CLONE_PTRACE;
}

- p = copy_process(clone_flags, stack_start, regs, stack_size, user_tid);
+ p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr);
if (!IS_ERR(p)) {
struct completion vfork;

--- linux/kernel/sched.c.orig 2002-11-20 09:25:45.000000000 +0100
+++ linux/kernel/sched.c 2002-11-20 09:26:49.000000000 +0100
@@ -503,12 +503,12 @@
* schedule_tail - first thing a freshly forked thread must call.
* @prev: the thread we just switched away from.
*/
-#if CONFIG_SMP || CONFIG_PREEMPT
asmlinkage void schedule_tail(task_t *prev)
{
finish_arch_switch(this_rq(), prev);
+ if (current->set_child_tid)
+ put_user(current->pid, current->set_child_tid);
}
-#endif

/*
* context_switch - switch to the new MM and the new
-
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