On Tue, 19 Nov 2002, Ulrich Drepper wrote:
> Ingo's last patch has two pointer, one for the parent and one for the
> child. [...]
i was waiting for you to test that patch - there's no point in trying to
put in untested patches. The previous patch i'm sure would not have worked
without major surgery on the fork() side (like the creation of a new
thread descriptor for the child). The attached patch adds the following 3
clone flags:
CLONE_PARENT_SETTID - this sets the TID synchronously in the parent VM
only, parameter on x86 is in %esi.
CLONE_CHILD_SETTID - this sets the TID asynchronously in the child VM
only, parameter on x86 is in %edi.
CLONE_CHILD_CLEARTID - this clears the TID in the child VM upon exit()
or exec(), and wakes up futex waiters. Same
parameter as CLONE_CHILD_SETTID.
old CLONE_SETTID became CLONE_PARENT_SETTID, old CLONE_CLEARTID became
CLONE_CHILD_CLEARTID. CLONE_CHILD_SETTID is a new flag, 0x01000000.
please let me know whether this works, and it would also be nice to add
cfork() at the same time to make sure the interface and the semantics are
correct.
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, ®s, 0, NULL);
+ return do_fork(CLONE_VM|CLONE_IDLETASK, 0, ®s, 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 09:27:42.000000000 +0100
@@ -226,7 +226,7 @@
regs.eflags = 0x286;
/* Ok, create the new process.. */
- p = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL);
+ p = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 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, ®s, 0, NULL);
+ p = do_fork(SIGCHLD, regs.esp, ®s, 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.esi;
if (!newsp)
newsp = regs.esp;
- p = do_fork(clone_flags & ~CLONE_IDLETASK, newsp, ®s, 0, user_tid);
+ p = do_fork(clone_flags & ~CLONE_IDLETASK, newsp, ®s, 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, ®s, 0, NULL);
+ p = do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 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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This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:31 EST