lkml.org 
[lkml]   [2002]   [Nov]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [patch] threading fix, tid-2.5.47-A3

here are the my current TID-setting changes. It's now 3 clone flags:

- CLONE_PARENT_SETTID

race-free setting of the new TID/PID in the parent's address space.
This is done in do_fork(), before sys_fork() returns.

- CLONE_CHILD_SETTID

race-free setting of the new TID/PID in the child's address space.
this uses the ->user_tid field to delay setting of the TID when the
child context first runs. It's guaranteed to be set before the child's
first userspace instruction is executed, but has no specific ordering
with sys_clone() itself.

- CLONE_CHILD_CLEARTID

exit() time notification, clearing of the TID and futex wakeup. It's
guaranteed to be done after the last instruction of a context is
executed.

i've extended sys_clone() with a new argument (in %esi), which is the
child_tidaddr pointer. %edx is now the parent_tidaddr.

Ingo

--- linux/arch/i386/kernel/entry.S.orig 2002-11-17 20:54:55.000000000 +0100
+++ linux/arch/i386/kernel/entry.S 2002-11-17 20:57:44.000000000 +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/arch/i386/kernel/smpboot.c.orig 2002-11-17 21:12:49.000000000 +0100
+++ linux/arch/i386/kernel/smpboot.c 2002-11-17 21:12:52.000000000 +0100
@@ -498,7 +498,7 @@
* 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 2002-11-17 21:03:01.000000000 +0100
+++ linux/arch/i386/kernel/process.c 2002-11-17 21:11:52.000000000 +0100
@@ -225,7 +225,7 @@
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;
}

@@ -502,7 +502,7 @@
{
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;
}

@@ -511,14 +511,15 @@
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, &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;
}

@@ -536,7 +537,7 @@
{
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/include/linux/sched.h.orig 2002-11-17 20:53:52.000000000 +0100
+++ linux/include/linux/sched.h 2002-11-17 21:15:27.000000000 +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_SETTID 0x00200000 /* set the TID in the child */
+#define CLONE_CHILD_CLEARTID 0x00400000 /* clear the TID in the child */
+#define CLONE_DETACHED 0x00800000 /* parent wants no child-exit signal */
+#define CLONE_UNTRACED 0x01000000 /* set if the tracing process can't force CLONE_PTRACE on this clone */

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

wait_queue_head_t wait_chldexit; /* for wait4() */
struct completion *vfork_done; /* for vfork() */
- int *user_tid; /* for CLONE_CLEARTID */
+ int *user_tid; /* CLONE_CHILD_[SET|CLEAR]TID */

unsigned long rt_priority;
unsigned long it_real_value, it_prof_value, it_virt_value;
@@ -615,7 +616,7 @@
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/sched.c.orig 2002-11-17 20:52:30.000000000 +0100
+++ linux/kernel/sched.c 2002-11-17 21:12:03.000000000 +0100
@@ -503,12 +503,16 @@
* 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 FASTCALL(schedule_tail(task_t *prev));
asmlinkage void schedule_tail(task_t *prev)
{
finish_arch_switch(this_rq(), prev);
+ /*
+ * Does the child thread/process want to be notified of the TID/PID?
+ */
+ if (current->user_tid)
+ put_user(current->pid, current->user_tid);
}
-#endif

/*
* context_switch - switch to the new MM and the new
--- linux/kernel/fork.c.orig 2002-11-17 20:54:55.000000000 +0100
+++ linux/kernel/fork.c 2002-11-17 21:09:49.000000000 +0100
@@ -695,7 +695,8 @@
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;
@@ -819,19 +820,14 @@
retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
if (retval)
goto bad_fork_cleanup_namespace;
+ if (clone_flags & CLONE_PARENT_SETTID)
+ put_user(p->pid, parent_tidptr);
/*
- * Notify the child of the TID?
+ * Does the userspace VM want the TID set in the child's
+ * address space and it cleared on mm_release()?
*/
- retval = -EFAULT;
- if (clone_flags & CLONE_SETTID)
- if (put_user(p->pid, user_tid))
- goto bad_fork_cleanup_namespace;
-
- /*
- * Does the userspace VM want the TID cleared on mm_release()?
- */
- if (clone_flags & CLONE_CLEARTID)
- p->user_tid = user_tid;
+ if (clone_flags & CLONE_CHILD_SETTID)
+ p->user_tid = child_tidptr;

/*
* Syscall tracing should be turned off in the child regardless
@@ -1000,7 +996,8 @@
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;
@@ -1011,7 +1008,7 @@
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;

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:31    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site