From: Sven Schnelle <svens@stackframe.org>
Date: Wed, 5 Jun 2019 20:32:19 +0000 (+0200)
Subject: parisc: add WARN_ON() to clear_fixmap
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=e4eab1ce1f679507c02ea48e6b6edaef33f8fee3;p=openwrt%2Fstaging%2Fblogic.git

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 c8d41b54fb19..36321bcd75ba 100644
--- 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);