Messages in this thread | | | Date | Tue, 9 Apr 2024 23:40:03 +0300 | Subject | Re: [PATCH v5 3/6] nvme-tcp: short-circuit reconnect retries | From | Sagi Grimberg <> |
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On 09/04/2024 12:35, Daniel Wagner wrote: > From: Hannes Reinecke <hare@suse.de> > > Returning an nvme status from nvme_tcp_setup_ctrl() indicates that the > association was established and we have received a status from the > controller; consequently we should honour the DNR bit. If not any future > reconnect attempts will just return the same error, so we can > short-circuit the reconnect attempts and fail the connection directly. > > Signed-off-by: Hannes Reinecke <hare@suse.de> > [dwagner: add helper to decide to reconnect] > Signed-off-by: Daniel Wagner <dwagner@suse.de> > --- > drivers/nvme/host/nvme.h | 24 ++++++++++++++++++++++++ > drivers/nvme/host/tcp.c | 23 +++++++++++++++-------- > 2 files changed, 39 insertions(+), 8 deletions(-) > > diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h > index 9b8904a476b8..dfe103283a3d 100644 > --- a/drivers/nvme/host/nvme.h > +++ b/drivers/nvme/host/nvme.h > @@ -701,6 +701,30 @@ static inline bool nvme_is_path_error(u16 status) > return (status & 0x700) == 0x300; > } > > +/* > + * Evaluate the status information returned by the LLDD
We usually say transport, less so LLDD.
> in order to > + * decided if a reconnect attempt should be scheduled. > + * > + * There are two cases where no reconnect attempt should be attempted: > + * > + * 1) The LLDD reports an negative status. There was an error (e.g. no > + * memory) on the host side and thus abort the operation. > + * Note, there are exception such as ENOTCONN which is > + * not an internal driver error, thus we filter these errors > + * out and retry later.
What is this ENOTCONN here? From what I see its just a random escape value to bypass the status check. I think that 0 would do the same wouldn't it?
> + * 2) The DNR bit is set and the specification states no further > + * connect attempts with the same set of paramenters should be > + * attempted. > + */ > +static inline bool nvme_ctrl_reconnect(int status) > +{ > + if (status < 0 && status != -ENOTCONN) > + return false; > + else if (status > 0 && (status & NVME_SC_DNR)) > + return false; > + return true; > +} > + > /* > * Fill in the status and result information from the CQE, and then figure out > * if blk-mq will need to use IPI magic to complete the request, and if yes do > diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c > index fdbcdcedcee9..7e25a96e9870 100644 > --- a/drivers/nvme/host/tcp.c > +++ b/drivers/nvme/host/tcp.c > @@ -2155,9 +2155,11 @@ static void nvme_tcp_teardown_io_queues(struct nvme_ctrl *ctrl, > nvme_tcp_destroy_io_queues(ctrl, remove); > } > > -static void nvme_tcp_reconnect_or_remove(struct nvme_ctrl *ctrl) > +static void nvme_tcp_reconnect_or_remove(struct nvme_ctrl *ctrl, > + int status) > { > enum nvme_ctrl_state state = nvme_ctrl_state(ctrl); > + bool recon = nvme_ctrl_reconnect(status); > > /* If we are resetting/deleting then do nothing */ > if (state != NVME_CTRL_CONNECTING) { > @@ -2165,13 +2167,14 @@ static void nvme_tcp_reconnect_or_remove(struct nvme_ctrl *ctrl) > return; > } > > - if (nvmf_should_reconnect(ctrl)) { > + if (recon && nvmf_should_reconnect(ctrl)) {
its weird to have a condition that checks _and_ condition of two different "should reconnect" conditions.
Why don't we simply pass the status to nvmf_should_reconnect() and evaluate there?
> dev_info(ctrl->device, "Reconnecting in %d seconds...\n", > ctrl->opts->reconnect_delay); > queue_delayed_work(nvme_wq, &to_tcp_ctrl(ctrl)->connect_work, > ctrl->opts->reconnect_delay * HZ); > } else { > - dev_info(ctrl->device, "Removing controller...\n"); > + dev_info(ctrl->device, "Removing controller (%d)...\n", > + status); > nvme_delete_ctrl(ctrl); > } > } > @@ -2252,10 +2255,12 @@ static void nvme_tcp_reconnect_ctrl_work(struct work_struct *work) > struct nvme_tcp_ctrl *tcp_ctrl = container_of(to_delayed_work(work), > struct nvme_tcp_ctrl, connect_work); > struct nvme_ctrl *ctrl = &tcp_ctrl->ctrl; > + int ret; > > ++ctrl->nr_reconnects; > > - if (nvme_tcp_setup_ctrl(ctrl, false)) > + ret = nvme_tcp_setup_ctrl(ctrl, false); > + if (ret) > goto requeue; > > dev_info(ctrl->device, "Successfully reconnected (%d attempt)\n", > @@ -2268,7 +2273,7 @@ static void nvme_tcp_reconnect_ctrl_work(struct work_struct *work) > requeue: > dev_info(ctrl->device, "Failed reconnect attempt %d\n", > ctrl->nr_reconnects); > - nvme_tcp_reconnect_or_remove(ctrl); > + nvme_tcp_reconnect_or_remove(ctrl, ret); > } > > static void nvme_tcp_error_recovery_work(struct work_struct *work) > @@ -2295,7 +2300,7 @@ static void nvme_tcp_error_recovery_work(struct work_struct *work) > return; > } > > - nvme_tcp_reconnect_or_remove(ctrl); > + nvme_tcp_reconnect_or_remove(ctrl, -ENOTCONN); > } > > static void nvme_tcp_teardown_ctrl(struct nvme_ctrl *ctrl, bool shutdown) > @@ -2315,6 +2320,7 @@ static void nvme_reset_ctrl_work(struct work_struct *work) > { > struct nvme_ctrl *ctrl = > container_of(work, struct nvme_ctrl, reset_work); > + int ret; > > nvme_stop_ctrl(ctrl); > nvme_tcp_teardown_ctrl(ctrl, false); > @@ -2328,14 +2334,15 @@ static void nvme_reset_ctrl_work(struct work_struct *work) > return; > } > > - if (nvme_tcp_setup_ctrl(ctrl, false)) > + ret = nvme_tcp_setup_ctrl(ctrl, false); > + if (ret) > goto out_fail; > > return; > > out_fail: > ++ctrl->nr_reconnects; > - nvme_tcp_reconnect_or_remove(ctrl); > + nvme_tcp_reconnect_or_remove(ctrl, ret); > } > > static void nvme_tcp_stop_ctrl(struct nvme_ctrl *ctrl)
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