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    Subject[PATCH AUTOSEL 5.0 061/262] mm/resource: Return real error codes from walk failures
    Date
    From: Dave Hansen <dave.hansen@linux.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@linux.intel.com>
    Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
    Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
    Cc: Dan Williams <dan.j.williams@intel.com>
    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 <ying.huang@intel.com>
    Cc: Fengguang Wu <fengguang.wu@intel.com>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
    Cc: Takashi Iwai <tiwai@suse.de>
    Cc: Jerome Glisse <jglisse@redhat.com>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: linuxppc-dev@lists.ozlabs.org
    Cc: Keith Busch <keith.busch@intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    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
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