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nodeinfo: skip offline CPUs

Browse Source 
https://bugzilla.redhat.com/622515 - When hot-unplugging CPUs,
libvirt failed to start a guest that had been pinned to CPUs that
were still online.

Tested on a dual-core laptop, where I also discovered that, per
http://www.cyberciti.biz/files/linux-kernel/Documentation/cpu-hotplug.txt,
/sys/devices/system/cpu/cpu0/online does not exist on systems where it
cannot be hot-unplugged.

* src/nodeinfo.c (linuxNodeInfoCPUPopulate): Ignore CPUs that are
currently offline.  Detect readdir failure.
(parse_socket): Move guts...
(get_cpu_value): ...to new function, shared with...
(cpu_online): New function.
This commit is contained in:
Eric Blake 2010-08-10 15:33:37 -06:00
parent d1e5676c0d
commit d413e5d765
1 changed files with 76 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

112
src/nodeinfo.c
View File

@ -23,6 +23,7 @@
#include <config.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
@ -44,6 +45,7 @@
#include "logging.h"
#include "virterror_internal.h"
#include "count-one-bits.h"
#include "intprops.h"
#define VIR_FROM_THIS VIR_FROM_NONE
@ -60,6 +62,60 @@
int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
virNodeInfoPtr nodeinfo);
/* Return the positive decimal contents of the given
* CPU_SYS_PATH/cpu%u/FILE, or -1 on error. If MISSING_OK and the
* file could not be found, return 1 instead of an error; this is
* because some machines cannot hot-unplug cpu0. */
static int
get_cpu_value(unsigned int cpu, const char *file, bool missing_ok)
{
char *path;
FILE *pathfp;
int value = -1;
char value_str[INT_BUFSIZE_BOUND(value)];
char *tmp;
if (virAsprintf(&path, CPU_SYS_PATH "/cpu%u/%s", cpu, file) < 0) {
virReportOOMError();
return -1;
}
pathfp = fopen(path, "r");
if (pathfp == NULL) {
if (missing_ok && errno == ENOENT)
value = 1;
else
virReportSystemError(errno, _("cannot open %s"), path);
goto cleanup;
}
if (fgets(value_str, sizeof(value_str), pathfp) == NULL) {
virReportSystemError(errno, _("cannot read from %s"), path);
goto cleanup;
}
if (virStrToLong_i(value_str, &tmp, 10, &value) < 0) {
nodeReportError(VIR_ERR_INTERNAL_ERROR,
_("could not convert '%s' to an integer"),
value_str);
goto cleanup;
}
cleanup:
if (pathfp)
fclose(pathfp);
VIR_FREE(path);
return value;
}
/* Check if CPU is online via CPU_SYS_PATH/cpu%u/online. Return 1 if online,
0 if offline, and -1 on error. */
static int
cpu_online(unsigned int cpu)
{
return get_cpu_value(cpu, "online", cpu == 0);
}
static unsigned long count_thread_siblings(unsigned int cpu)
{
unsigned long ret = 0;
@ -106,41 +162,7 @@ cleanup:
static int parse_socket(unsigned int cpu)
{
char *path;
FILE *pathfp;
char socket_str[1024];
char *tmp;
int socket = -1;
if (virAsprintf(&path, CPU_SYS_PATH "/cpu%u/topology/physical_package_id",
cpu) < 0) {
virReportOOMError();
return -1;
}
pathfp = fopen(path, "r");
if (pathfp == NULL) {
virReportSystemError(errno, _("cannot open %s"), path);
VIR_FREE(path);
return -1;
}
if (fgets(socket_str, sizeof(socket_str), pathfp) == NULL) {
virReportSystemError(errno, _("cannot read from %s"), path);
goto cleanup;
}
if (virStrToLong_i(socket_str, &tmp, 10, &socket) < 0) {
nodeReportError(VIR_ERR_INTERNAL_ERROR,
_("could not convert '%s' to an integer"),
socket_str);
goto cleanup;
}
cleanup:
fclose(pathfp);
VIR_FREE(path);
return socket;
return get_cpu_value(cpu, "topology/physical_package_id", false);
}
int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
@ -153,6 +175,8 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
unsigned long cur_threads;
int socket;
unsigned long long socket_mask = 0;
unsigned int remaining;
int online;
nodeinfo->cpus = 0;
nodeinfo->mhz = 0;
@ -222,15 +246,25 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
/* OK, we've parsed what we can out of /proc/cpuinfo. Get the socket
* and thread information from /sys
*/
remaining = nodeinfo->cpus;
cpudir = opendir(CPU_SYS_PATH);
if (cpudir == NULL) {
virReportSystemError(errno, _("cannot opendir %s"), CPU_SYS_PATH);
return -1;
}
while ((cpudirent = readdir(cpudir))) {
while ((errno = 0), remaining && (cpudirent = readdir(cpudir))) {
if (sscanf(cpudirent->d_name, "cpu%u", &cpu) != 1)
continue;
online = cpu_online(cpu);
if (online < 0) {
closedir(cpudir);
return -1;
}
if (!online)
continue;
remaining--;
socket = parse_socket(cpu);
if (socket < 0) {
closedir(cpudir);
@ -249,6 +283,12 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
if (cur_threads > nodeinfo->threads)
nodeinfo->threads = cur_threads;
}
if (errno) {
virReportSystemError(errno,
_("problem reading %s"), CPU_SYS_PATH);
closedir(cpudir);
return -1;
}
closedir(cpudir);