selftests/powerpc: Fix online CPU selection

The size of the CPU affinity mask must be large enough for
systems with a very large number of CPUs. Otherwise, tests
which try to determine the first online CPU by calling
sched_getaffinity() will fail. This makes sure that the size
of the allocated affinity mask is dependent on the number of
CPUs as reported by get_nprocs_conf().

Fixes: 3752e453f6ba ("selftests/powerpc: Add tests of PMU EBBs")
Reported-by: Shirisha Ganta <shiganta@in.ibm.com>
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a408c4b8e9a23bb39b539417a21eb0ff47bb5127.1596084858.git.sandipan@linux.ibm.com

diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index 933678f1ed0a0ea23171c500b748943ef2c41e90..18b6a773d5c7362a5fc2e6251191eb4aadedc569 100644 (file)
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -16,6 +16,7 @@
 #include <string.h>
 #include <sys/ioctl.h>
 #include <sys/stat.h>
+#include <sys/sysinfo.h>
 #include <sys/types.h>
 #include <sys/utsname.h>
 #include <unistd.h>
@@ -88,28 +89,40 @@ void *get_auxv_entry(int type)
 
 int pick_online_cpu(void)
 {
-       cpu_set_t mask;
-       int cpu;
+       int ncpus, cpu = -1;
+       cpu_set_t *mask;
+       size_t size;
+
+       ncpus = get_nprocs_conf();
+       size = CPU_ALLOC_SIZE(ncpus);
+       mask = CPU_ALLOC(ncpus);
+       if (!mask) {
+               perror("malloc");
+               return -1;
+       }
 
-       CPU_ZERO(&mask);
+       CPU_ZERO_S(size, mask);
 
-       if (sched_getaffinity(0, sizeof(mask), &mask)) {
+       if (sched_getaffinity(0, size, mask)) {
                perror("sched_getaffinity");
-               return -1;
+               goto done;
        }
 
        /* We prefer a primary thread, but skip 0 */
-       for (cpu = 8; cpu < CPU_SETSIZE; cpu += 8)
-               if (CPU_ISSET(cpu, &mask))
-                       return cpu;
+       for (cpu = 8; cpu < ncpus; cpu += 8)
+               if (CPU_ISSET_S(cpu, size, mask))
+                       goto done;
 
        /* Search for anything, but in reverse */
-       for (cpu = CPU_SETSIZE - 1; cpu >= 0; cpu--)
-               if (CPU_ISSET(cpu, &mask))
-                       return cpu;
+       for (cpu = ncpus - 1; cpu >= 0; cpu--)
+               if (CPU_ISSET_S(cpu, size, mask))
+                       goto done;
 
        printf("No cpus in affinity mask?!\n");
-       return -1;
+
+done:
+       CPU_FREE(mask);
+       return cpu;
 }
 
 bool is_ppc64le(void)