On 14.10.18 10:54, Philippe Gerum wrote:
The CPU affinity mask in __base_setup_data.cpu_affinity - which may be
set by --cpu-affinity - is conventionally checked by applications for
determining which CPUs are usable for real-time duties.
Over Cobalt, we need to make sure that such mask reflects the set of
CPUs available for running real-time threads as defined by the core
(i.e. /proc/xenomai/affinity), in absence of --cpu-affinity
setting.
Otherwise, some applications like switchest looking at an empty
affinity mask may wrongly assume that all CPUs are available for
running RT threads, leading to a failure when manually pinning such
thread to an invalid (non-RT) CPU.
With current Cobalt core and I-pipe releases not fixed for gracefully
handling invalid domain migration requests over a non-RT CPU, such a
failure may trigger a kernel panic.
Signed-off-by: Philippe Gerum <r...@xenomai.org>
---
lib/boilerplate/setup.c | 33 +++++++++++++++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)
diff --git a/lib/boilerplate/setup.c b/lib/boilerplate/setup.c
index 8b363efee..3214d7f04 100644
--- a/lib/boilerplate/setup.c
+++ b/lib/boilerplate/setup.c
@@ -173,6 +173,8 @@ static int collect_cpu_affinity(const char *cpu_list)
return ret;
}
+ CPU_ZERO(&__base_setup_data.cpu_affinity);
+
s = n = strdup(cpu_list);
while ((range = strtok_r(n, ",", &range_p)) != NULL) {
if (*range == '\0')
@@ -232,6 +234,33 @@ fail:
return -EINVAL;
}
+static void retrieve_default_cpu_affinity(void)
+{
+ CPU_ZERO(&__base_setup_data.cpu_affinity);
+
+#ifdef CONFIG_XENO_COBALT
+ /*
+ * If the Cobalt core has restricted the CPU set, update our
+ * mask accordingly.
+ */
+ unsigned long cpumask;
+ FILE *fp;
+ int cpu;
+
+ fp = fopen("/proc/xenomai/affinity", "r");
+ if (fp == NULL)
+ return; /* uhh? */
+
+ if (fscanf(fp, "%lx", &cpumask) == 1) {
+ for (cpu = 0; cpumask; cpumask >>= 1, cpu++)
+ if (cpumask & 1)
+ CPU_SET(cpu, &__base_setup_data.cpu_affinity);
+ }
+
+ fclose(fp);
+#endif
+}
+
static inline char **prep_args(int argc, char *const argv[])
{
char **uargv;
@@ -528,8 +557,8 @@ static void __xenomai_init(int *argcp, char *const **argvp,
const char *me)
/* No ifs, no buts: we must be called over the main thread. */
assert(getpid() == __node_id);
- /* Define default CPU affinity, i.e. no particular affinity. */
- CPU_ZERO(&__base_setup_data.cpu_affinity);
+ /* Retrieve the default CPU affinity. */
+ retrieve_default_cpu_affinity();
/*
* Parse the base options first, to bootstrap the core with
Thanks, applied to next.
Am I right that this as well as most of the patches in the original series are
also stable candidates?
Jan
--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
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