block/iscsi: fix potential segfault on early callback

it might happen in the future that a function directly invokes its callback.
In this case we end up in a segfault because the iTask is gone when the BH
is scheduled.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/iscsi.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Il 10/06/2014 09:52, Peter Lieven ha scritto:
> it might happen in the future that a function directly invokes its callback.
> In this case we end up in a segfault because the iTask is gone when the BH
> is scheduled.
>
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/iscsi.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 019b324..4bf4238 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -146,6 +146,7 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
>  static void iscsi_co_generic_bh_cb(void *opaque)
>  {
>      struct IscsiTask *iTask = opaque;
> +    iTask->complete = 1;
>      qemu_bh_delete(iTask->bh);
>      qemu_coroutine_enter(iTask->co, NULL);
>  }
> @@ -153,6 +154,7 @@ static void iscsi_co_generic_bh_cb(void *opaque)
>  static void iscsi_retry_timer_expired(void *opaque)
>  {
>      struct IscsiTask *iTask = opaque;
> +    iTask->complete = 1;
>      if (iTask->co) {
>          qemu_coroutine_enter(iTask->co, NULL);
>      }
> @@ -171,7 +173,6 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
>      struct IscsiTask *iTask = opaque;
>      struct scsi_task *task = command_data;
>
> -    iTask->complete = 1;
>      iTask->status = status;
>      iTask->do_retry = 0;
>      iTask->task = task;
> @@ -209,6 +210,8 @@ out:
>          iTask->bh = aio_bh_new(iTask->iscsilun->aio_context,
>                                 iscsi_co_generic_bh_cb, iTask);
>          qemu_bh_schedule(iTask->bh);
> +    } else {
> +        iTask->complete = 1;
>      }
>  }
>
>

Applied, thanks.  I'll leave the nfs patch to Kevin and/or Stefan.

Paolo

On 10.06.2014 10:08, Paolo Bonzini wrote:
> Il 10/06/2014 09:52, Peter Lieven ha scritto:
>> it might happen in the future that a function directly invokes its callback.
>> In this case we end up in a segfault because the iTask is gone when the BH
>> is scheduled.
>>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>>  block/iscsi.c |    5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/block/iscsi.c b/block/iscsi.c
>> index 019b324..4bf4238 100644
>> --- a/block/iscsi.c
>> +++ b/block/iscsi.c
>> @@ -146,6 +146,7 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
>>  static void iscsi_co_generic_bh_cb(void *opaque)
>>  {
>>      struct IscsiTask *iTask = opaque;
>> +    iTask->complete = 1;
>>      qemu_bh_delete(iTask->bh);
>>      qemu_coroutine_enter(iTask->co, NULL);
>>  }
>> @@ -153,6 +154,7 @@ static void iscsi_co_generic_bh_cb(void *opaque)
>>  static void iscsi_retry_timer_expired(void *opaque)
>>  {
>>      struct IscsiTask *iTask = opaque;
>> +    iTask->complete = 1;
>>      if (iTask->co) {
>>          qemu_coroutine_enter(iTask->co, NULL);
>>      }
>> @@ -171,7 +173,6 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
>>      struct IscsiTask *iTask = opaque;
>>      struct scsi_task *task = command_data;
>>
>> -    iTask->complete = 1;
>>      iTask->status = status;
>>      iTask->do_retry = 0;
>>      iTask->task = task;
>> @@ -209,6 +210,8 @@ out:
>>          iTask->bh = aio_bh_new(iTask->iscsilun->aio_context,
>>                                 iscsi_co_generic_bh_cb, iTask);
>>          qemu_bh_schedule(iTask->bh);
>> +    } else {
>> +        iTask->complete = 1;
>>      }
>>  }
>>
>>
>
> Applied, thanks.  I'll leave the nfs patch to Kevin and/or Stefan.

Thank you,

Stefan/Kevin I messed up the commit message. Can you please fix when picking up:

---8<---

it will happen in the future that a function directly invokes its callback.
In this case we end up in a segfault because the NFSRPC is gone when we the
BH is scheduled.

--->8---

Thanks,
Peter