linux-kernel - [PATCH 1/4] arch/powerpc: Clean up error handling for htab_remove

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Date:	Thu, 28 Jan 2016 13:41:03 +1100
From:	David Gibson <david@...son.dropbear.id.au>
To:	mpe@...erman.id.au, benh@...nel.crashing.org
Cc:	paulus@...ba.org, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	David Gibson <david@...son.dropbear.id.au>
Subject: [PATCH 1/4] arch/powerpc: Clean up error handling for htab_remove_mapping

Currently, the only error that htab_remove_mapping() can report is -EINVAL,
if removal of bolted HPTEs isn't implemeted for this platform.  We make
a few clean ups to the handling of this:

 * EINVAL isn't really the right code - there's nothing wrong with the
   function's arguments - use ENODEV instead
 * We were also printing a warning message, but that's a decision better
   left up to the callers, so remove it
 * One caller is vmemmap_remove_mapping(), which will just BUG_ON() on
   error, making the warning message irrelevant, so no change is needed
   there.
 * The other caller is remove_section_mapping().  This is called in the
   memory hot remove path at a point after vmemmap_remove_mapping() so
   if hpte_removebolted isn't implemented, we'd expect to have already
   BUG()ed anyway.  Put a WARN_ON() here, in lieu of a printk() since this
   really shouldn't be happening.

Signed-off-by: David Gibson <david@...son.dropbear.id.au>
---
 arch/powerpc/mm/hash_utils_64.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index ba59d59..9f7d727 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -273,11 +273,8 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 	shift = mmu_psize_defs[psize].shift;
 	step = 1 << shift;

-	if (!ppc_md.hpte_removebolted) {
-		printk(KERN_WARNING "Platform doesn't implement "
-				"hpte_removebolted\n");
-		return -EINVAL;
-	}
+	if (!ppc_md.hpte_removebolted)
+		return -ENODEV;

 	for (vaddr = vstart; vaddr < vend; vaddr += step)
 		ppc_md.hpte_removebolted(vaddr, psize, ssize);
@@ -641,8 +638,10 @@ int create_section_mapping(unsigned long start, unsigned long end)

 int remove_section_mapping(unsigned long start, unsigned long end)
 {
-	return htab_remove_mapping(start, end, mmu_linear_psize,
-			mmu_kernel_ssize);
+	int rc = htab_remove_mapping(start, end, mmu_linear_psize,
+				     mmu_kernel_ssize);
+	WARN_ON(rc < 0);
+	return rc;
 }
 #endif /* CONFIG_MEMORY_HOTPLUG */

-- 
2.5.0