Blackfin arch: fix bug: kernel prints out error message twice

This fixes two things:
 - stop calling write_lock_irq/write_unlock_irq which can turn modify
   irq levels
 - don't calling mmput when handing exceptions - since this might_sleep,
   which does a rti, and leaves us in kernel space (irq15, rather
   than irq5).

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index afd044e..ce86659 100644 (file)
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -54,12 +54,13 @@ void __init trap_init(void)
 int kstack_depth_to_print = 48;
 
 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
-static int printk_address(unsigned long address)
+static void printk_address(unsigned long address)
 {
        struct vm_list_struct *vml;
        struct task_struct *p;
        struct mm_struct *mm;
-       unsigned long offset;
+       unsigned long flags, offset;
+       unsigned int in_exception = bfin_read_IPEND() & 0x10;
 
 #ifdef CONFIG_KALLSYMS
        unsigned long symsize;
@@ -75,9 +76,10 @@ static int printk_address(unsigned long address)
                /* yeah! kernel space! */
                if (!modname)
                        modname = delim = "";
-               return printk("<0x%p> { %s%s%s%s + 0x%lx }",
+               printk("<0x%p> { %s%s%s%s + 0x%lx }",
                              (void *)address, delim, modname, delim, symname,
                              (unsigned long)offset);
+               return;
 
        }
 #endif
@@ -86,9 +88,9 @@ static int printk_address(unsigned long address)
         * mappings of all our processes and see if we can't be a whee
         * bit more specific
         */
-       write_lock_irq(&tasklist_lock);
+       write_lock_irqsave(&tasklist_lock, flags);
        for_each_process(p) {
-               mm = get_task_mm(p);
+               mm = (in_exception ? p->mm : get_task_mm(p));
                if (!mm)
                        continue;
 
@@ -117,20 +119,24 @@ static int printk_address(unsigned long address)
                                else
                                        offset = (address - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
 
-                               write_unlock_irq(&tasklist_lock);
-                               mmput(mm);
-                               return printk("<0x%p> [ %s + 0x%lx ]",
-                                             (void *)address, name, offset);
+                               printk("<0x%p> [ %s + 0x%lx ]",
+                                       (void *)address, name, offset);
+                               if (!in_exception)
+                                       mmput(mm);
+                               goto done;
                        }
 
                        vml = vml->next;
                }
-               mmput(mm);
+               if (!in_exception)
+                       mmput(mm);
        }
-       write_unlock_irq(&tasklist_lock);
 
        /* we were unable to find this address anywhere */
-       return printk("[<0x%p>]", (void *)address);
+       printk("[<0x%p>]", (void *)address);
+
+done:
+       write_unlock_irqrestore(&tasklist_lock, flags);
 }
 #endif