Commit 60f53782 authored by Paul E. McKenney's avatar Paul E. McKenney

rcu: Prevent initialization race in rcutorture kthreads

When you do something like "t = kthread_run(...)", it is possible that
the kthread will start running before the assignment to "t" happens.
If the child kthread expects to find a pointer to its task_struct in "t",
it will then be fatally disappointed.  This commit therefore switches
such cases to kthread_create() followed by wake_up_process(), guaranteeing
that the assignment happens before the child kthread starts running.
Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 2caa1e44
......@@ -2029,7 +2029,7 @@ rcu_torture_init(void)
/* Start up the kthreads. */
VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
writer_task = kthread_run(rcu_torture_writer, NULL,
writer_task = kthread_create(rcu_torture_writer, NULL,
"rcu_torture_writer");
if (IS_ERR(writer_task)) {
firsterr = PTR_ERR(writer_task);
......@@ -2037,6 +2037,7 @@ rcu_torture_init(void)
writer_task = NULL;
goto unwind;
}
wake_up_process(writer_task);
fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
GFP_KERNEL);
if (fakewriter_tasks == NULL) {
......@@ -2151,7 +2152,7 @@ rcu_torture_init(void)
}
if (shutdown_secs > 0) {
shutdown_time = jiffies + shutdown_secs * HZ;
shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
"rcu_torture_shutdown");
if (IS_ERR(shutdown_task)) {
firsterr = PTR_ERR(shutdown_task);
......@@ -2159,6 +2160,7 @@ rcu_torture_init(void)
shutdown_task = NULL;
goto unwind;
}
wake_up_process(shutdown_task);
}
i = rcu_torture_onoff_init();
if (i != 0) {
......
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