Re: [libvirt] [RFC][PATCH] lxc: fix for ns cgroups subsystem

Hi Serge and Daniel, On Sat, May 9, 2009 at 4:03 AM, Serge E. Hallyn <serue(a)us.ibm.com&gt; wrote: OK I probably understood the problem and wrote a patch for that according to the Serge's suggestion. I expect this patch fixes the problem, however unfortunately I've not tried it yet under the situation you are worrying and just done regression tests. Because I don't know easy way to produce the situation. If you know that, please let me know... Thanks, ozaki-r From: Ryota Ozaki <ozaki.ryota(a)gmail.com&gt; Date: Sun, 10 May 2009 08:32:41 +0900 Subject: [PATCH] cgroups: address libvirtd's bad assumption for cgroups hierarchy --- src/cgroup.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 files changed, 70 insertions(+), 8 deletions(-) diff --git a/src/cgroup.c b/src/cgroup.c index 50517e2..e02c37f 100644 --- a/src/cgroup.c +++ b/src/cgroup.c @@ -117,11 +117,60 @@ int virCgroupHaveSupport(void) return 0; } +static int virCgroupGetCurrentPath(int pid, char **curpath) +{ + char buf[PATH_MAX+1024]; + char *path = NULL; + int rc = 0; + int len; + int fd; + char *pos = NULL; + + if (virAsprintf(&path, "/proc/%d/cgroup", pid) == -1) { + rc = -ENOMEM; + goto error; + } + + fd = open(path, O_RDONLY); + if (fd < 0) { + DEBUG("Unable to open %s: %m", path); + rc = -errno; + goto error_open; + } + + len = saferead(fd, buf, sizeof(buf)); + if (len <= 0) { + rc = -errno; + goto error_saferead; + } + buf[len-1] = '¥0'; /* overwrite '¥n' */ + + pos = strstr(buf, ":/"); + if (pos == NULL) { + rc = -1; + goto error_strstr; + } + + pos += 2; /* skip ':/' */ + if (virAsprintf(curpath, "%s", pos) == -1) { + rc = -ENOMEM; + } + +error_strstr: +error_saferead: + close(fd); +error_open: + VIR_FREE(path); +error: + return rc; +} + static int virCgroupPathOfGroup(const char *group, const char *controller, char **path) { virCgroupPtr root = NULL; + char *curpath = NULL; int rc = 0; root = virCgroupGetMount(controller); @@ -130,8 +179,14 @@ static int virCgroupPathOfGroup(const char *group, goto out; } - if (virAsprintf(path, "%s/%s", root->path, group) == -1) + rc = virCgroupGetCurrentPath(getpid(), &curpath); + if (rc < 0) + goto out; + + if (virAsprintf(path, "%s/%s/%s", root->path, curpath, group) == -1) rc = -ENOMEM; + + VIR_FREE(curpath); out: virCgroupFree(&root); @@ -145,6 +200,7 @@ static int virCgroupPathOf(const char *grppath, virCgroupPtr root; int rc = 0; char *controller = NULL; + char *curpath = NULL; if (strchr(key, '.') == NULL) return -EINVAL; @@ -158,8 +214,14 @@ static int virCgroupPathOf(const char *grppath, goto out; } - if (virAsprintf(path, "%s/%s/%s", root->path, grppath, key) == -1) + rc = virCgroupGetCurrentPath(getpid(), &curpath); + if (rc < 0) + goto out; + + if (virAsprintf(path, "%s/%s/%s/%s", root->path, curpath, grppath, key) == -1) rc = -ENOMEM; + + VIR_FREE(curpath); out: virCgroupFree(&root); VIR_FREE(controller); @@ -625,15 +687,14 @@ int virCgroupAddTask(virCgroupPtr group, pid_t pid) char *grppath = NULL; char *taskpath = NULL; char *pidstr = NULL; + virCgroupPtr root; for (i = 0; supported_controllers[i] != NULL; i++) { - rc = virCgroupPathOfGroup(group->path, - supported_controllers[i], - &grppath); - if (rc != 0) - goto done; + root = virCgroupGetMount(supported_controllers[i]); + if (root == NULL) + continue; - if (virAsprintf(&taskpath, "%s/tasks", grppath) == -1) { + if (virAsprintf(&taskpath, "%s/%s/tasks", root->path, group->path) == -1) { rc = -ENOMEM; goto done; } @@ -655,6 +716,7 @@ int virCgroupAddTask(virCgroupPtr group, pid_t pid) } done: + virCgroupFree(&root); VIR_FREE(grppath); VIR_FREE(taskpath); VIR_FREE(pidstr); -- 1.6.0.6