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    Subject[PATCH 4.4 10/36] x86/mmiotrace: Use cpumask_available() for cpumask_var_t variables
    Date
    From: Nathan Chancellor <natechancellor@gmail.com>

    [ Upstream commit d7110a26e5905ec2fe3fc88bc6a538901accb72b ]

    When building with Clang + -Wtautological-compare and
    CONFIG_CPUMASK_OFFSTACK unset:

    arch/x86/mm/mmio-mod.c:375:6: warning: comparison of array 'downed_cpus'
    equal to a null pointer is always false [-Wtautological-pointer-compare]
    if (downed_cpus == NULL &&
    ^~~~~~~~~~~ ~~~~
    arch/x86/mm/mmio-mod.c:405:6: warning: comparison of array 'downed_cpus'
    equal to a null pointer is always false [-Wtautological-pointer-compare]
    if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
    ^~~~~~~~~~~ ~~~~
    2 warnings generated.

    Commit

    f7e30f01a9e2 ("cpumask: Add helper cpumask_available()")

    added cpumask_available() to fix warnings of this nature. Use that here
    so that clang does not warn regardless of CONFIG_CPUMASK_OFFSTACK's
    value.

    Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
    Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
    Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Link: https://github.com/ClangBuiltLinux/linux/issues/982
    Link: https://lkml.kernel.org/r/20200408205323.44490-1-natechancellor@gmail.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/mm/mmio-mod.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
    index 0057a7accfb1..5448ad4d0703 100644
    --- a/arch/x86/mm/mmio-mod.c
    +++ b/arch/x86/mm/mmio-mod.c
    @@ -385,7 +385,7 @@ static void enter_uniprocessor(void)
    int cpu;
    int err;

    - if (downed_cpus == NULL &&
    + if (!cpumask_available(downed_cpus) &&
    !alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) {
    pr_notice("Failed to allocate mask\n");
    goto out;
    @@ -415,7 +415,7 @@ static void leave_uniprocessor(void)
    int cpu;
    int err;

    - if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
    + if (!cpumask_available(downed_cpus) || cpumask_weight(downed_cpus) == 0)
    return;
    pr_notice("Re-enabling CPUs...\n");
    for_each_cpu(cpu, downed_cpus) {
    --
    2.25.1


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