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Subject[PATCH AUTOSEL 4.14 05/13] 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 4d434ddb75db..f140b2d39319 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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