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drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES

As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
This leads to very large file sizes:

topology$ ls -l
total 0
-r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
-r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
-r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
-r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
-r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
-r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
-r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
-r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
-r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
-r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
-r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
-r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
-r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list

Adjust the inequality to catch the case when NR_CPUS is configured
to a small value.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: stable@vger.kernel.org
Cc: feng xiangjun <fengxj325@gmail.com>
Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
Reported-by: feng xiangjun <fengxj325@gmail.com>
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>

authored by

Phil Auld and committed by
Yury Norov
b9be19ee 7e18e42e

+3 -2
+3 -2
include/linux/cpumask.h
··· 1127 1127 * cover a worst-case of every other cpu being on one of two nodes for a 1128 1128 * very large NR_CPUS. 1129 1129 * 1130 - * Use PAGE_SIZE as a minimum for smaller configurations. 1130 + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding 1131 + * unsigned comparison to -1. 1131 1132 */ 1132 - #define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \ 1133 + #define CPUMAP_FILE_MAX_BYTES (((NR_CPUS * 9)/32 > PAGE_SIZE) \ 1133 1134 ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE) 1134 1135 #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE) 1135 1136