[CRIU] [PATCH 08/12] crtools: restore pending signals

[Andrey Wagin]

2012/12/18 Pavel Emelyanov <xemul at parallels.com>:
>> @@ -1596,6 +1645,9 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
>>
>>       struct task_restore_core_args *task_args;
>>       struct thread_restore_args *thread_args;
>> +     siginfo_t *siginfo_chunk;
>> +     int siginfo_nr = 0;
>> +     unsigned long siginfo_size = PAGE_SIZE;
>
> A question. Why do we restore pending signals in restorer, not in generic code?
Thread penging signals could not be restored, because threads are not exist yet.
SIGCHLD signal can't be restored in generic code too.

>
>>       LIST_HEAD(self_vma_list);
>>       int i;
>> @@ -1644,12 +1696,55 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
>>       task_args       = mem;
>>       thread_args     = mem + restore_task_vma_len;
>>
>> +     siginfo_chunk = mmap(NULL, siginfo_size, PROT_READ | PROT_WRITE,
>> +                                             MAP_PRIVATE | MAP_ANON, 0, 0);
>> +     if (mem == MAP_FAILED) {
>> +             pr_err("Can't allocate memory for siginfo-s\n");
>> +             goto err;
>> +     }
>
> This first mmap looks ugly. Re-mplement remapping in open_signal_image to
> hide one.
>
>> +
>> +     ret = open_signal_image(CR_FD_SIGNAL, pid, &siginfo_chunk,
>> +                                     &siginfo_size, &siginfo_nr);
>> +     if (ret < 0) {
>> +             if (errno != ENOENT) /* backward compatiblity */
>> +                     goto err;
>> +             ret = 0;
>> +     }
>> +     task_args->siginfo_nr = ret;
>> +
>> +     ret = open_signal_image(CR_FD_PSIGNAL, pid, &siginfo_chunk,
>> +                                     &siginfo_size, &siginfo_nr);
>> +     if (ret < 0) {
>> +             if (errno != ENOENT) /* backward compatiblity */
>> +                     goto err;
>> +             ret = 0;
>> +     }
>> +     task_args->t.siginfo_nr = ret;
>> +
>> +     for (i = 0; i < current->nr_threads; i++) {
>
> We have already a loop that initialized thread restore data. This siginfos
> read-in should be there.
>
>> +             thread_args[i].pid = current->threads[i].virt;
>> +             /* skip self */
>> +             if (thread_args[i].pid == pid)
>> +                     continue;
>> +
>> +             ret = open_signal_image(CR_FD_PSIGNAL,
>> +                                     thread_args[i].pid, &siginfo_chunk,
>> +                                     &siginfo_size, &siginfo_nr);
>> +             if (ret < 0) {
>> +                     if (errno != ENOENT) /* backward compatiblity */
>> +                             goto err;
>> +                     ret = 0;
>> +             }
>> +             thread_args[i].siginfo_nr = ret;
>> +     }
>> +
>>       restore_bootstrap_len = restorer_len +
>>                               restore_task_vma_len +
>>                               restore_thread_vma_len +
>>                               SHMEMS_SIZE + TASK_ENTRIES_SIZE +
>>                               self_vmas_len + vmas_len +
>> -                             rst_tcp_socks_size;
>> +                             rst_tcp_socks_size +
>> +                             siginfo_size;
>>
>>       /*
>>        * Restorer is a blob (code + args) that will get mapped in some
>> diff --git a/include/restorer.h b/include/restorer.h
>> index 2309a3d..f7a762d 100644
>> --- a/include/restorer.h
>> +++ b/include/restorer.h
>> @@ -79,6 +79,9 @@ struct thread_restore_args {
>>       struct rst_sched_param          sp;
>>
>>       struct task_restore_core_args   *ta;
>> +
>> +     siginfo_t                       *siginfo;
>> +     unsigned int                    siginfo_nr;
>>  } __aligned(sizeof(long));
>>
>>  struct task_restore_core_args {
>> @@ -98,6 +101,9 @@ struct task_restore_core_args {
>>       struct task_entries             *task_entries;
>>       VmaEntry                        *self_vmas;
>>       VmaEntry                        *tgt_vmas;
>> +     siginfo_t                       *siginfo;
>> +     unsigned int                    siginfo_nr;
>> +     unsigned long                   siginfo_size;
>
> What for? Master thread's siginfos are in respective thread-info.
>
>>       unsigned int                    nr_vmas;
>>       unsigned long                   premmapped_addr;
>>       unsigned long                   premmapped_len;