• Lu Jialin's avatar
    crypto: pcrypt - Fix hungtask for PADATA_RESET · 8f4f68e7
    Lu Jialin authored
    We found a hungtask bug in test_aead_vec_cfg as follows:
    
    INFO: task cryptomgr_test:391009 blocked for more than 120 seconds.
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    Call trace:
     __switch_to+0x98/0xe0
     __schedule+0x6c4/0xf40
     schedule+0xd8/0x1b4
     schedule_timeout+0x474/0x560
     wait_for_common+0x368/0x4e0
     wait_for_completion+0x20/0x30
     wait_for_completion+0x20/0x30
     test_aead_vec_cfg+0xab4/0xd50
     test_aead+0x144/0x1f0
     alg_test_aead+0xd8/0x1e0
     alg_test+0x634/0x890
     cryptomgr_test+0x40/0x70
     kthread+0x1e0/0x220
     ret_from_fork+0x10/0x18
     Kernel panic - not syncing: hung_task: blocked tasks
    
    For padata_do_parallel, when the return err is 0 or -EBUSY, it will call
    wait_for_completion(&wait->completion) in test_aead_vec_cfg. In normal
    case, aead_request_complete() will be called in pcrypt_aead_serial and the
    return err is 0 for padata_do_parallel. But, when pinst->flags is
    PADATA_RESET, the return err is -EBUSY for padata_do_parallel, and it
    won't call aead_request_complete(). Therefore, test_aead_vec_cfg will
    hung at wait_for_completion(&wait->completion), which will cause
    hungtask.
    
    The problem comes as following:
    (padata_do_parallel)                 |
        rcu_read_lock_bh();              |
        err = -EINVAL;                   |   (padata_replace)
                                         |     pinst->flags |= PADATA_RESET;
        err = -EBUSY                     |
        if (pinst->flags & PADATA_RESET) |
            rcu_read_unlock_bh()         |
            return err
    
    In order to resolve the problem, we replace the return err -EBUSY with
    -EAGAIN, which means parallel_data is changing, and the caller should call
    it again.
    
    v3:
    remove retry and just change the return err.
    v2:
    introduce padata_try_do_parallel() in pcrypt_aead_encrypt and
    pcrypt_aead_decrypt to solve the hungtask.
    Signed-off-by: default avatarLu Jialin <lujialin4@huawei.com>
    Signed-off-by: default avatarGuo Zihua <guozihua@huawei.com>
    Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
    8f4f68e7
pcrypt.c 9.23 KB