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 673de6063345..92530af38b09 100644 --- a/arch/x86/mm/mmio-mod.c +++ b/arch/x86/mm/mmio-mod.c @@ -372,7 +372,7 @@ 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; @@ -402,7 +402,7 @@ 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) {