travis: add build environment information to the travis log

[strace] / affinity.c

diff --git a/affinity.c b/affinity.c
index 24d5edbaf6d9cff049e62ca55c0ed0bfbcc83236..0eb109404c0b8ae5acf79f2a83882d0e66f1aee3 100644 (file)
--- a/affinity.c
+++ b/affinity.c
@@ -35,10 +35,21 @@ get_cpuset_size(void)
        static unsigned int cpuset_size;
 
        if (!cpuset_size) {
-               pid_t pid = getpid();
+               /*
+                * If the cpuset size passed to sched_getaffinity is less
+                * than necessary to store the bitmask, the kernel does not
+                * look at the mask pointer and fails with EINVAL.
+                *
+                * If the cpuset size is large enough, the kernel fails with
+                * EFAULT on inaccessible mask pointers.
+                *
+                * This undocumented kernel feature can be used to probe
+                * the kernel and find out the minimal valid cpuset size
+                * without allocating any memory for the CPU affinity mask.
+                */
                cpuset_size = 128;
                while (cpuset_size &&
-                      sched_getaffinity(pid, cpuset_size, NULL) == -1 &&
+                      sched_getaffinity(0, cpuset_size, NULL) == -1 &&
                       EINVAL == errno) {
                        cpuset_size <<= 1;
                }
@@ -50,7 +61,8 @@ get_cpuset_size(void)
 }
 
 static void
-print_affinitylist(struct tcb *tcp, const unsigned long addr, const unsigned int len)
+print_affinitylist(struct tcb *const tcp, const kernel_ulong_t addr,
+                  const unsigned int len)
 {
        const unsigned int max_size = get_cpuset_size();
        const unsigned int umove_size = len < max_size ? len : max_size;