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

    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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