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>

1 files changed, 18 insertions, 12 deletions

diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index afd044e78af6..ce86659f9b65 100644
--- 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