Serge E. Hallyn wrote: > Quoting Oren Laadan ([email protected]): >> Ensure that all members of a thread group are in sys_restart before >> restoring any of them. Otherwise, restore may modify shared state and >> crash or fault a thread still in userspace, >> >> For thread groups, each thread scans the entire group and tests for >> PF_RESTARTING on every member. If not all are set, then we wait, and >> when woken up try again (unless signaled). If all are set, then we're >> done and wakeup all threads. >> >> Signed-off-by: Oren Laadan <[email protected]> >> --- >> checkpoint/restart.c | 52 >> ++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 files changed, 52 insertions(+), 0 deletions(-) >> >> diff --git a/checkpoint/restart.c b/checkpoint/restart.c >> index 5d936cf..37454c5 100644 >> --- a/checkpoint/restart.c >> +++ b/checkpoint/restart.c >> @@ -695,6 +695,54 @@ static int do_ghost_task(void) >> /* NOT REACHED */ >> } >> >> +/* >> + * Ensure that all members of a thread group are in sys_restart before >> + * restoring any of them. Otherwise, restore may modify shared state >> + * and crash or fault a thread still in userspace, >> + */ >> +static int wait_sync_threads(void) >> +{ >> + struct task_struct *p, *leader; >> + >> + if (thread_group_empty(current)) >> + return 0; >> + >> + p = leader = current->group_leader; >> + >> + /* >> + * Our PF_RESTARTING is already set. Each thread loops through >> + * the group testing everyone's PF_RESTARTING. If not set on >> + * all members, it sleeps to retry later. Otherwise it wakes >> + * up all sleepers and returns. >> + */ >> + retry: >> + __set_current_state(TASK_INTERRUPTIBLE); >> + >> + read_lock(&tasklist_lock); >> + do { >> + if (!(p->flags & PF_RESTARTING)) >> + break; >> + p = next_thread(p); >> + } while (p != leader); >> + >> + if (p != leader) { >> + read_unlock(&tasklist_lock); >> + if (signal_pending(current)) > > Not sure... but do you need to get back to TASK_RUNNING > in this case? (the schedule() below does it automatically, > but not this failure case)
Correct. But as you suggested over IRC, I'll change the logic to avoid unnecessary loops there. Oren. _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
