Commit ef70eff9 authored Dec 04, 2019 by Nathan Chancellor Committed by Linus Torvalds Dec 04, 2019

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 f7e30f01 ("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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 260a2679

kernel/profile.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -336,7 +336,7 @@ static int profile_dead_cpu(unsigned int cpu)
		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 int cpu)

		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));
		}

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