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authorThomas Gleixner <tglx@linutronix.de>2016-12-13 19:32:28 +0100
committerThomas Gleixner <tglx@linutronix.de>2016-12-15 11:32:31 +0100
commit427d77a32365d5f942d335248305a5c237baf63a (patch)
treebc71ce672cf89239bdd90b15a1a5e39e2123fa10 /include/linux/cpumask.h
parent31dcfec11f827e9a5d8720fe4728f1305894884f (diff)
x86/smpboot: Prevent false positive out of bounds cpumask access warning
prefill_possible_map() reinitializes the cpu_possible_map by setting the possible cpu bits and clearing all other bits up to NR_CPUS. This is technically always correct because cpu_possible_map is statically allocated and sized NR_CPUS. With CPUMASK_OFFSTACK and DEBUG_PER_CPU_MAPS enabled the bounds check of cpu masks happens on nr_cpu_ids. nr_cpu_ids is initialized to NR_CPUS and only limited after the set/clear bit loops have been executed. But if the system was booted with "nr_cpus=N" on the command line, where N is < NR_CPUS then nr_cpu_ids is limited in the parameter parsing function before prefill_possible_map() is invoked. As a consequence the cpumask bounds check triggers when clearing the bits past nr_cpu_ids. Add a helper which allows to reset cpu_possible_map w/o the bounds check and then set only the possible bits which are well inside bounds. Reported-by: Dmitry Safonov <dsafonov@virtuozzo.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: 0x7f454c46@gmail.com Cc: Jan Beulich <JBeulich@novell.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1612131836050.3415@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/cpumask.h')
-rw-r--r--include/linux/cpumask.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index da7fbf1cdd56..c717f5ea88cb 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -722,6 +722,11 @@ void init_cpu_present(const struct cpumask *src);
void init_cpu_possible(const struct cpumask *src);
void init_cpu_online(const struct cpumask *src);
+static inline void reset_cpu_possible_mask(void)
+{
+ bitmap_zero(cpumask_bits(&__cpu_possible_mask), NR_CPUS);
+}
+
static inline void
set_cpu_possible(unsigned int cpu, bool possible)
{