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crypto: pcrypt - Fix hungtask for PADATA_RESET

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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: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Guo Zihua <guozihua@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Lu Jialin 2023-09-04 13:33:41 +00:00 committed by Herbert Xu
parent 6b36dafedd
commit 8f4f68e788
2 changed files with 5 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
crypto/pcrypt.c
View file

@ -117,6 +117,8 @@ static int pcrypt_aead_encrypt(struct aead_request *req)
err = padata_do_parallel(ictx->psenc, padata, &ctx->cb_cpu);
if (!err)
return -EINPROGRESS;
if (err == -EBUSY)
return -EAGAIN;
return err;
}
@ -164,6 +166,8 @@ static int pcrypt_aead_decrypt(struct aead_request *req)
err = padata_do_parallel(ictx->psdec, padata, &ctx->cb_cpu);
if (!err)
return -EINPROGRESS;
if (err == -EBUSY)
return -EAGAIN;
return err;
}

2
kernel/padata.c
View file

@ -202,7 +202,7 @@ int padata_do_parallel(struct padata_shell *ps,
*cb_cpu = cpu;
}
err = -EBUSY;
err = -EBUSY;
if ((pinst->flags & PADATA_RESET))
goto out;