Re: [Qemu-devel] [PATCH] iscsi: fix deadlock during login

[ronnie sahlberg]

I dont know if we should switch to use synchronous code here.
It is much nicer if all code is async.

Is it possible to add a timeout instead that would break out if the
connect/login has not completed within a certain amount of time?


regards
ronnie sahlberg

On Thu, Nov 15, 2012 at 6:50 AM, Peter Lieven <address@hidden> wrote:
> If the connection is interrupted before the first login is successfully
> completed qemu-kvm is waiting forever in qemu_aio_wait().
>
> This is fixed by performing an sync login to the target. If the
> connection breaks after the first successful login errors are
> handled internally by libiscsi.
>
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  block/iscsi.c |   56
> +++++++++++++++++++++-----------------------------------
>  1 file changed, 21 insertions(+), 35 deletions(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index b5c3161..f44bb57 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -798,30 +798,6 @@ iscsi_inquiry_cb(struct iscsi_context *iscsi, int
> status, void *command_data,
>      }
>  }
>
> -static void
> -iscsi_connect_cb(struct iscsi_context *iscsi, int status, void
> *command_data,
> -                 void *opaque)
> -{
> -    struct IscsiTask *itask = opaque;
> -    struct scsi_task *task;
> -
> -    if (status != 0) {
> -        itask->status   = 1;
> -        itask->complete = 1;
> -        return;
> -    }
> -
> -    task = iscsi_inquiry_task(iscsi, itask->iscsilun->lun,
> -                              0, 0, 36,
> -                              iscsi_inquiry_cb, opaque);
> -    if (task == NULL) {
> -        error_report("iSCSI: failed to send inquiry command.");
> -        itask->status   = 1;
> -        itask->complete = 1;
> -        return;
> -    }
> -}
> -
>  static int parse_chap(struct iscsi_context *iscsi, const char *target)
>  {
>      QemuOptsList *list;
> @@ -934,7 +910,8 @@ static int iscsi_open(BlockDriverState *bs, const char
> *filename, int flags)
>      IscsiLun *iscsilun = bs->opaque;
>      struct iscsi_context *iscsi = NULL;
>      struct iscsi_url *iscsi_url = NULL;
> -    struct IscsiTask task;
> +    struct IscsiTask itask;
> +    struct scsi_task *task;
>      char *initiator_name = NULL;
>      int ret;
>
> @@ -997,27 +974,36 @@ static int iscsi_open(BlockDriverState *bs, const char
> *filename, int flags)
>      /* check if we got HEADER_DIGEST via the options */
>      parse_header_digest(iscsi, iscsi_url->target);
>
> -    task.iscsilun = iscsilun;
> -    task.status = 0;
> -    task.complete = 0;
> -    task.bs = bs;
> +    if (iscsi_full_connect_sync(iscsi, iscsi_url->portal, iscsi_url->lun)
> != 0) {
> +        error_report("iSCSI: Failed to connect to LUN : %s",
> +            iscsi_get_error(iscsi));
> +        ret = -EINVAL;
> +        goto out;
> +    }
> +
> +    itask.iscsilun = iscsilun;
> +    itask.status = 0;
> +    itask.complete = 0;
> +    itask.bs = bs;
>
>      iscsilun->iscsi = iscsi;
>      iscsilun->lun   = iscsi_url->lun;
>
> -    if (iscsi_full_connect_async(iscsi, iscsi_url->portal, iscsi_url->lun,
> -                                 iscsi_connect_cb, &task)
> -        != 0) {
> -        error_report("iSCSI: Failed to start async connect.");
> +    task = iscsi_inquiry_task(iscsi, iscsilun->lun,
> +                              0, 0, 36,
> +                              iscsi_inquiry_cb, &itask);
> +    if (task == NULL) {
> +        error_report("iSCSI: failed to send inquiry command.");
>          ret = -EINVAL;
>          goto out;
>      }
>
> -    while (!task.complete) {
> +    while (!itask.complete) {
>          iscsi_set_events(iscsilun);
>          qemu_aio_wait();
>      }
> -    if (task.status != 0) {
> +
> +    if (itask.status != 0) {
>          error_report("iSCSI: Failed to connect to LUN : %s",
>                       iscsi_get_error(iscsi));
>          ret = -EINVAL;
> --
> 1.7.9.5