On Sat, Aug 3, 2019 at 12:58 AM Mike Christie <mchristi@xxxxxxxxxx> wrote:
>
> On 08/02/2019 05:38 AM, Li Zhong wrote:
> > If the userspace process crashes while we send the nl msg, it is possible
> > that the cmd in curr_nl_cmd of tcmu_dev never gets reset to 0, and
> > and returns busy for other commands after the userspace process is
> > restartd.
> >
> > More details below:
> >
> > /backstores/user:file/file> set attribute dev_size=2048
> > Cannot set attribute dev_size: [Errno 3] No such process
> > /backstores/user:file/file> set attribute dev_size=2048
> > Cannot set attribute dev_size: [Errno 16] Device or resource busy
> >
> > with following kernel messages:
> > [173605.747169] Unable to reconfigure device
> > [173616.686674] tcmu daemon: command reply support 1.
> > [173623.866978] netlink cmd 3 already executing on file
> > [173623.866984] Unable to reconfigure device
> >
> > Also, it is not safe to leave the nl_cmd in the list, and not get
> > deleted.
> >
> > This patch removes the nl_cmd from the list, and clear its data if
> > it is not sent successfully.
> >
> > Signed-off-by: Li Zhong <lizhongfs@xxxxxxxxx>
> > ---
> > drivers/target/target_core_user.c | 21 +++++++++++++++++++++
> > 1 file changed, 21 insertions(+)
> >
> > diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
> > index 04eda111920e..4ae3103e204c 100644
> > --- a/drivers/target/target_core_user.c
> > +++ b/drivers/target/target_core_user.c
> > @@ -1708,6 +1708,24 @@ static int tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
> > return 0;
> > }
> >
> > +static void tcmu_destroy_genl_cmd_reply(struct tcmu_dev *udev)
> > +{
> > + struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
> > +
> > + if (!tcmu_kern_cmd_reply_supported)
> > + return;
> > +
> > + if (udev->nl_reply_supported <= 0)
> > + return;
> > +
> > + mutex_lock(&tcmu_nl_cmd_mutex);
> > +
> > + list_del(&nl_cmd->nl_list);
> > + memset(nl_cmd, 0, sizeof(*nl_cmd));
> > +
> > + mutex_unlock(&tcmu_nl_cmd_mutex);
> > +}
> > +
> > static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
> > {
> > struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
> > @@ -1788,6 +1806,9 @@ static int tcmu_netlink_event_send(struct tcmu_dev *udev,
> > if (ret == 0 ||
> > (ret == -ESRCH && cmd == TCMU_CMD_ADDED_DEVICE))
> > return tcmu_wait_genl_cmd_reply(udev);
> > + else
> > + /* If failure, remove from the list and clear the nl_cmd */
>
> Drop the comment. We know it is in the failure path already and the
> function name tells us it cleans up the command.
Thank you for the review, Will drop it.
>
> > + tcmu_destroy_genl_cmd_reply(udev);
> >
>
