[patch 22/86] kernel/profile.c: use cpumask_available to check for NULL cpumask

Andrew Morton
2019-12-05T00:50:53Z

From: Nathan Chancellor <natechancellor@gmail.com>
Subject: kernel/profile.c: use cpumask_available to check for NULL cpumask

When building with clang + -Wtautological-pointer-compare, these instances
pop up:

kernel/profile.c:339:6: warning: comparison of array 'prof_cpu_mask' not
equal to a null pointer is always true [-Wtautological-pointer-compare]
if (prof_cpu_mask != NULL)
^~~~~~~~~~~~~ ~~~~
kernel/profile.c:376:6: warning: comparison of array 'prof_cpu_mask' not
equal to a null pointer is always true [-Wtautological-pointer-compare]
if (prof_cpu_mask != NULL)
^~~~~~~~~~~~~ ~~~~
kernel/profile.c:406:26: warning: comparison of array 'prof_cpu_mask'
not equal to a null pointer is always true
[-Wtautological-pointer-compare]
if (!user_mode(regs) && prof_cpu_mask != NULL &&
^~~~~~~~~~~~~ ~~~~
3 warnings generated.

This can be addressed with the cpumask_available helper, introduced in
commit f7e30f01a9e2 ("cpumask: Add helper cpumask_available()") to fix
warnings like this while keeping the code the same.

Link: https://github.com/ClangBuiltLinux/linux/issues/747
Link: http://lkml.kernel.org/r/20191022191957.9554-1-natechancellor@gmail.com
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

kernel/profile.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/profile.c~kernel-profile-use-cpumask_available-to-check-for-null-cpumask
+++ a/kernel/profile.c
@@ -336,7 +336,7 @@ static int profile_dead_cpu(unsigned int
struct page *page;
int i;

- if (prof_cpu_mask != NULL)
+ if (cpumask_available(prof_cpu_mask))
cpumask_clear_cpu(cpu, prof_cpu_mask);

for (i = 0; i < 2; i++) {
@@ -373,7 +373,7 @@ static int profile_prepare_cpu(unsigned

static int profile_online_cpu(unsigned int cpu)
{
- if (prof_cpu_mask != NULL)
+ if (cpumask_available(prof_cpu_mask))
cpumask_set_cpu(cpu, prof_cpu_mask);

return 0;
@@ -403,7 +403,7 @@ void profile_tick(int type)
{
struct pt_regs *regs = get_irq_regs();

- if (!user_mode(regs) && prof_cpu_mask != NULL &&
+ if (!user_mode(regs) && cpumask_available(prof_cpu_mask) &&
cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
profile_hit(type, (void *)profile_pc(regs));
}
_