lkml.org 
[lkml]   [2014]   [Jul]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
On Fri, Jul 4, 2014 at 7:07 PM, Emil Goode <emilgoode@gmail.com> wrote:
> We check that the struct vm_area_struct pointer vma is NULL and
> then dereference it. The intent must have been to check that
> vma is not NULL before we dereference it in the next condition.

Actually if it is NULL, then it will short-cut and won't dereference
it (because !vma is true it can never become false again), so the
condition would be fine previously.

But, looking at the code a few lines into branch:

if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
unsigned long flags;
int oldpid, newpid, idx;

#ifdef DEBUG_TLB
printk("[tlbpage<%lu,0x%08lx>]", cpu_context(cpu,
vma->vm_mm), page);
#endif
newpid = cpu_context(cpu, vma->vm_mm) & ASID_MASK;

it will be then dereferenced here, so the change is actually sensible,
even if the description isn't quite spot-on where it breaks.


Jonas


\
 
 \ /
  Last update: 2014-07-05 00:41    [W:0.057 / U:0.360 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site