Hi Ingo,

This patch makes ptrace_attach() use the new API write_trylock_irqsave(). With 
this, the code in ptrace_attach() will be same for mainline and -rt. On -rt, 
write_trylock_irqsave() doesn't disable irqs and hence the problem is 
avoided.

Signed-off-by: Sripathi Kodi <[EMAIL PROTECTED]>

Index: linux-2.6.21-rt1_patch/kernel/ptrace.c
===================================================================
--- linux-2.6.21-rt1_patch.orig/kernel/ptrace.c 2007-05-10 11:28:57.000000000 
+0530
+++ linux-2.6.21-rt1_patch/kernel/ptrace.c      2007-05-10 11:29:13.000000000 
+0530
@@ -160,6 +160,7 @@
 int ptrace_attach(struct task_struct *task)
 {
        int retval;
+       unsigned long flags;
 
        retval = -EPERM;
        if (task->pid <= 1)
@@ -178,9 +179,7 @@
         * cpu's that may have task_lock).
         */
        task_lock(task);
-       local_irq_disable();
-       if (!write_trylock(&tasklist_lock)) {
-               local_irq_enable();
+       if (!write_trylock_irqsave(&tasklist_lock, flags)) {
                task_unlock(task);
                do {
                        cpu_relax();
@@ -208,7 +207,7 @@
        force_sig_specific(SIGSTOP, task);
 
 bad:
-       write_unlock_irq(&tasklist_lock);
+       write_unlock_irqrestore(&tasklist_lock, flags);
        task_unlock(task);
 out:
        return retval;

-
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