Re: [patch] threading fix, tid-2.5.47-A3

From: Ingo Molnar (mingo@elte.hu)
Date: Sun Nov 17 2002 - 17:08:41 EST

ok, the attached patch also does the return-check of the parent-tidptr
put_user() call:

--- 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 22:52:25.000000000 +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 +820,18 @@
         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))
- goto bad_fork_cleanup_namespace;
 
+ if (clone_flags & CLONE_PARENT_SETTID)
+ if (put_user(p->pid, parent_tidptr)) {
+ retval = -EFAULT;
+ goto bad_fork_cleanup_namespace;
+ }
         /*
- * Does the userspace VM want the TID cleared on mm_release()?
+ * Does the userspace VM want the TID set in the child's
+ * address space and it 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 +1000,8 @@
                             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 +1012,7 @@
                         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;
 

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This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:19 EST