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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-08-26 00:27:40 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-09-23 16:42:23 +0200 |
| commit | 60f53782c51f27c695840ce90c6c432284319eef (patch) | |
| tree | daf20b20a35f09ecfa214127cf3c676f12c4edd1 /kernel/rcutorture.c | |
| parent | rcu: Switch rcutorture to pr_alert() and friends (diff) | |
| download | linux-60f53782c51f27c695840ce90c6c432284319eef.tar.xz linux-60f53782c51f27c695840ce90c6c432284319eef.zip | |
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: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutorture.c')
| -rw-r--r-- | kernel/rcutorture.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 61be03ba598d..aaa7b9f3532a 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -2029,14 +2029,15 @@ rcu_torture_init(void) /* Start up the kthreads. */ VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task"); - writer_task = kthread_run(rcu_torture_writer, NULL, - "rcu_torture_writer"); + writer_task = kthread_create(rcu_torture_writer, NULL, + "rcu_torture_writer"); if (IS_ERR(writer_task)) { firsterr = PTR_ERR(writer_task); VERBOSE_PRINTK_ERRSTRING("Failed to create writer"); writer_task = NULL; goto unwind; } + wake_up_process(writer_task); fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]), GFP_KERNEL); if (fakewriter_tasks == NULL) { @@ -2151,14 +2152,15 @@ rcu_torture_init(void) } if (shutdown_secs > 0) { shutdown_time = jiffies + shutdown_secs * HZ; - shutdown_task = kthread_run(rcu_torture_shutdown, NULL, - "rcu_torture_shutdown"); + shutdown_task = kthread_create(rcu_torture_shutdown, NULL, + "rcu_torture_shutdown"); if (IS_ERR(shutdown_task)) { firsterr = PTR_ERR(shutdown_task); VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown"); shutdown_task = NULL; goto unwind; } + wake_up_process(shutdown_task); } i = rcu_torture_onoff_init(); if (i != 0) { |