linux-kernel - [PATCH AUTOSEL 5.0 061/262] mm/resource: Return real error codes from walk failures

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Date:   Wed, 27 Mar 2019 13:58:36 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ross Zwisler <zwisler@...nel.org>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>, linux-nvdimm@...ts.01.org,
        linux-mm@...ck.org, Huang Ying <ying.huang@...el.com>,
        Fengguang Wu <fengguang.wu@...el.com>,
        Borislav Petkov <bp@...e.de>,
        Yaowei Bai <baiyaowei@...s.chinamobile.com>,
        Takashi Iwai <tiwai@...e.de>,
        Jerome Glisse <jglisse@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, Keith Busch <keith.busch@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.0 061/262] mm/resource: Return real error codes from walk failures

From: Dave Hansen <dave.hansen@...ux.intel.com>

[ 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@...ux.intel.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Michael Ellerman <mpe@...erman.id.au> (powerpc)
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Ross Zwisler <zwisler@...nel.org>
Cc: Vishal Verma <vishal.l.verma@...el.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: linux-nvdimm@...ts.01.org
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org
Cc: Huang Ying <ying.huang@...el.com>
Cc: Fengguang Wu <fengguang.wu@...el.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Yaowei Bai <baiyaowei@...s.chinamobile.com>
Cc: Takashi Iwai <tiwai@...e.de>
Cc: Jerome Glisse <jglisse@...hat.com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: Keith Busch <keith.busch@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.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