parisc: add WARN_ON() to clear_fixmap

Calling clear_fixmap() on an already cleared fixed mapping is
a bad thing to do. Add a WARN_ON() to catch such issues.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/mm/fixmap.c b/arch/parisc/mm/fixmap.c
index c8d41b5..36321bc 100644 (file)
--- a/arch/parisc/mm/fixmap.c
+++ b/arch/parisc/mm/fixmap.c
@@ -35,6 +35,9 @@ void clear_fixmap(enum fixed_addresses idx)
        pmd_t *pmd = pmd_offset(pgd, vaddr);
        pte_t *pte = pte_offset_kernel(pmd, vaddr);
 
+       if (WARN_ON(pte_none(*pte)))
+               return;
+
        pte_clear(&init_mm, vaddr, pte);
 
        flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);