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| author | Sander Vanheule <sander@svanheule.net> | 2022-07-02 18:08:25 +0200 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-07-18 02:31:41 +0200 |
| commit | b81dce77cedcea6f00292f02d4b1ebbfc2c5988d (patch) | |
| tree | 1b8f5a819bfcf58de29dc1a31301dc5893056a86 /lib | |
| parent | cpumask: add UP optimised for_each_*_cpu versions (diff) | |
| download | linux-b81dce77cedcea6f00292f02d4b1ebbfc2c5988d.tar.xz linux-b81dce77cedcea6f00292f02d4b1ebbfc2c5988d.zip | |
cpumask: Fix invalid uniprocessor mask assumption
On uniprocessor builds, any CPU mask is assumed to contain exactly one CPU
(cpu0). This assumption ignores the existence of empty masks, resulting
in incorrect behaviour.
cpumask_first_zero(), cpumask_next_zero(), and for_each_cpu_not() don't
provide behaviour matching the assumption that a UP mask is always "1",
and instead provide behaviour matching the empty mask.
Drop the incorrectly optimised code and use the generic implementations in
all cases.
Link: https://lkml.kernel.org/r/86bf3f005abba2d92120ddd0809235cab4f759a6.1656777646.git.sander@svanheule.net
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Suggested-by: Yury Norov <yury.norov@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 3 | ||||
| -rw-r--r-- | lib/cpumask.c | 2 |
2 files changed, 3 insertions, 2 deletions
diff --git a/lib/Makefile b/lib/Makefile index f99bf61f8bbc..bcc7e8ea0cde 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -34,10 +34,9 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ is_single_threaded.o plist.o decompress.o kobject_uevent.o \ earlycpio.o seq_buf.o siphash.o dec_and_lock.o \ nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o \ - buildid.o + buildid.o cpumask.o lib-$(CONFIG_PRINTK) += dump_stack.o -lib-$(CONFIG_SMP) += cpumask.o lib-y += kobject.o klist.o obj-y += lockref.o diff --git a/lib/cpumask.c b/lib/cpumask.c index a971a82d2f43..b9728513a4d4 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -192,6 +192,7 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask) } #endif +#if NR_CPUS > 1 /** * cpumask_local_spread - select the i'th cpu with local numa cpu's first * @i: index number @@ -279,3 +280,4 @@ int cpumask_any_distribute(const struct cpumask *srcp) return next; } EXPORT_SYMBOL(cpumask_any_distribute); +#endif /* NR_CPUS */ |