[PATCH 5.0 057/246] mm/resource: Return real error codes from walk failures

5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 5cd401ace914dc68556c6d2fcae0c349444d5f86 ]

walk_system_ram_range() can return an error code either becuase
*it* failed, or because the 'func' that it calls returned an
error.  The memory hotplug does the following:

	ret = walk_system_ram_range(..., func);
        if (ret)
		return ret;

and 'ret' makes it out to userspace, eventually.  The problem
s, walk_system_ram_range() failues that result from *it* failing
(as opposed to 'func') return -1.  That leads to a very odd
-EPERM (-1) return code out to userspace.

Make walk_system_ram_range() return -EINVAL for internal
failures to keep userspace less confused.

This return code is compatible with all the callers that I
audited.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Dan Williams <redacted>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <redacted>
Cc: Fengguang Wu <redacted>
Cc: Borislav Petkov <redacted>
Cc: Yaowei Bai <redacted>
Cc: Takashi Iwai <redacted>
Cc: Jerome Glisse <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Keith Busch <redacted>
Signed-off-by: Dan Williams <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/resource.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 915c02e8e5dd..ca7ed5158cff 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c

@@ -382,7 +382,7 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
 				 int (*func)(struct resource *, void *))
 {
 	struct resource res;
-	int ret = -1;
+	int ret = -EINVAL;
 
 	while (start < end &&
 	       !find_next_iomem_res(start, end, flags, desc, first_lvl, &res)) {

@@ -462,7 +462,7 @@ int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 	unsigned long flags;
 	struct resource res;
 	unsigned long pfn, end_pfn;
-	int ret = -1;
+	int ret = -EINVAL;
 
 	start = (u64) start_pfn << PAGE_SHIFT;
 	end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;

-- 
2.19.1