selftests/powerpc: Fix online CPU selection

[ Upstream commit dfa03fff86027e58c8dba5c03ae68150d4e513ad ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index d46916867a6fbcf627bd1fe2d45574decc8c9de8..77db4f6ecf2f0b86b200c9d704396f373001233f 100644 (file)
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -12,6 +12,7 @@
 #include <sched.h>
 #include <stdio.h>
 #include <sys/stat.h>
+#include <sys/sysinfo.h>
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -81,26 +82,38 @@ 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;
 }