* to continue to serve a useful existence. Next time it's released,
* we will get notified again, if it still has 'notify_on_release' set.
*
- * Note final arg to call_usermodehelper() is 0 - that means
- * don't wait. Since we are holding the global cpuset_sem here,
- * and we are asking another thread (started from keventd) to rmdir a
- * cpuset, we can't wait - or we'd deadlock with the removing thread
- * on cpuset_sem.
+ * The final arg to call_usermodehelper() is 0, which means don't
+ * wait. The separate /sbin/cpuset_release_agent task is forked by
+ * call_usermodehelper(), then control in this thread returns here,
+ * without waiting for the release agent task. We don't bother to
+ * wait because the caller of this routine has no use for the exit
+ * status of the /sbin/cpuset_release_agent task, so no sense holding
+ * our caller up for that.
+ *
+ * The simple act of forking that task might require more memory,
+ * which might need cpuset_sem. So this routine must be called while
+ * cpuset_sem is not held, to avoid a possible deadlock. See also
+ * comments for check_for_release(), below.
*/
-static int cpuset_release_agent(char *cpuset_str)
+static void cpuset_release_agent(const char *pathbuf)
{
char *argv[3], *envp[3];
int i;
+ if (!pathbuf)
+ return;
+
i = 0;
argv[i++] = "/sbin/cpuset_release_agent";
- argv[i++] = cpuset_str;
+ argv[i++] = (char *)pathbuf;
argv[i] = NULL;
i = 0;
envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
envp[i] = NULL;
- return call_usermodehelper(argv[0], argv, envp, 0);
+ call_usermodehelper(argv[0], argv, envp, 0);
+ kfree(pathbuf);
}
/*
* Either cs->count of using tasks transitioned to zero, or the
* cs->children list of child cpusets just became empty. If this
* cs is notify_on_release() and now both the user count is zero and
- * the list of children is empty, send notice to user land.
+ * the list of children is empty, prepare cpuset path in a kmalloc'd
+ * buffer, to be returned via ppathbuf, so that the caller can invoke
+ * cpuset_release_agent() with it later on, once cpuset_sem is dropped.
+ * Call here with cpuset_sem held.
+ *
+ * This check_for_release() routine is responsible for kmalloc'ing
+ * pathbuf. The above cpuset_release_agent() is responsible for
+ * kfree'ing pathbuf. The caller of these routines is responsible
+ * for providing a pathbuf pointer, initialized to NULL, then
+ * calling check_for_release() with cpuset_sem held and the address
+ * of the pathbuf pointer, then dropping cpuset_sem, then calling
+ * cpuset_release_agent() with pathbuf, as set by check_for_release().
*/
-static void check_for_release(struct cpuset *cs)
+static void check_for_release(struct cpuset *cs, char **ppathbuf)
{
if (notify_on_release(cs) && atomic_read(&cs->count) == 0 &&
list_empty(&cs->children)) {
if (!buf)
return;
if (cpuset_path(cs, buf, PAGE_SIZE) < 0)
- goto out;
- cpuset_release_agent(buf);
-out:
- kfree(buf);
+ kfree(buf);
+ else
+ *ppathbuf = buf;
}
}
* Call with cpuset_sem held. May nest a call to the
* lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
*/
+
+/*
+ * Hack to avoid 2.6.13 partial node dynamic sched domain bug.
+ * Disable letting 'cpu_exclusive' cpusets define dynamic sched
+ * domains, until the sched domain can handle partial nodes.
+ * Remove this #if hackery when sched domains fixed.
+ */
+#if 0
static void update_cpu_domains(struct cpuset *cur)
{
struct cpuset *c, *par = cur->parent;
partition_sched_domains(&pspan, &cspan);
unlock_cpu_hotplug();
}
+#else
+static void update_cpu_domains(struct cpuset *cur)
+{
+}
+#endif
static int update_cpumask(struct cpuset *cs, char *buf)
{
return 0;
}
-static int attach_task(struct cpuset *cs, char *buf)
+static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
{
pid_t pid;
struct task_struct *tsk;
struct cpuset *oldcs;
cpumask_t cpus;
- if (sscanf(buf, "%d", &pid) != 1)
+ if (sscanf(pidbuf, "%d", &pid) != 1)
return -EIO;
if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
return -ENOSPC;
put_task_struct(tsk);
if (atomic_dec_and_test(&oldcs->count))
- check_for_release(oldcs);
+ check_for_release(oldcs, ppathbuf);
return 0;
}
struct cftype *cft = __d_cft(file->f_dentry);
cpuset_filetype_t type = cft->private;
char *buffer;
+ char *pathbuf = NULL;
int retval = 0;
/* Crude upper limit on largest legitimate cpulist user might write. */
retval = update_flag(CS_NOTIFY_ON_RELEASE, cs, buffer);
break;
case FILE_TASKLIST:
- retval = attach_task(cs, buffer);
+ retval = attach_task(cs, buffer, &pathbuf);
break;
default:
retval = -EINVAL;
retval = nbytes;
out2:
up(&cpuset_sem);
+ cpuset_release_agent(pathbuf);
out1:
kfree(buffer);
return retval;
struct cpuset *cs = dentry->d_fsdata;
struct dentry *d;
struct cpuset *parent;
+ char *pathbuf = NULL;
/* the vfs holds both inode->i_sem already */
update_cpu_domains(cs);
list_del(&cs->sibling); /* delete my sibling from parent->children */
if (list_empty(&parent->children))
- check_for_release(parent);
+ check_for_release(parent, &pathbuf);
spin_lock(&cs->dentry->d_lock);
d = dget(cs->dentry);
cs->dentry = NULL;
cpuset_d_remove_dir(d);
dput(d);
up(&cpuset_sem);
+ cpuset_release_agent(pathbuf);
return 0;
}
task_unlock(tsk);
if (notify_on_release(cs)) {
+ char *pathbuf = NULL;
+
down(&cpuset_sem);
if (atomic_dec_and_test(&cs->count))
- check_for_release(cs);
+ check_for_release(cs, &pathbuf);
up(&cpuset_sem);
+ cpuset_release_agent(pathbuf);
} else {
atomic_dec(&cs->count);
}
projects / linux-2.6-omap-h63xx.git / blobdiff