diff options
| -rw-r--r-- | kernel/ptrace.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index b0f8da80d7d4..921c22ad16e4 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -155,8 +155,26 @@ int ptrace_attach(struct task_struct *task) if (task->tgid == current->tgid) goto out; - write_lock_irq(&tasklist_lock); +repeat: + /* + * Nasty, nasty. + * + * We want to hold both the task-lock and the + * tasklist_lock for writing at the same time. + * But that's against the rules (tasklist_lock + * is taken for reading by interrupts on other + * cpu's that may have task_lock). + */ task_lock(task); + local_irq_disable(); + if (!write_trylock(&tasklist_lock)) { + local_irq_enable(); + task_unlock(task); + do { + cpu_relax(); + } while (!write_can_lock(&tasklist_lock)); + goto repeat; + } /* the same process cannot be attached many times */ if (task->ptrace & PT_PTRACED) |