When a delayed event is enqueued then the event worker will send this
event the next time it is running and no other flow is currently
active. The event handler is called for the delayed event, and the
pointer to the event keeps set in lgr->delayed_event. This pointer is
cleared later in the processing by smc_llc_flow_start().
This can lead to a use-after-free condition when the processing does not
reach smc_llc_flow_start(), but frees the event because of an error
situation. Then the delayed_event pointer is still set but the event is
freed.
Fix this by always clearing the delayed event pointer when the event is
provided to the event handler for processing, and remove the code to
clear it in smc_llc_flow_start().

Fixes: 555da9af ("net/smc: add event-based llc_flow framework")
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

For older versions of gcc, the array = {0}; will cause warnings:

net/smc/smc_llc.c: In function 'smc_llc_add_link_local':
net/smc/smc_llc.c:1212:9: warning: missing braces around initializer [-Wmissing-braces]
  struct smc_llc_msg_add_link add_llc = {0};
         ^
net/smc/smc_llc.c:1212:9: warning: (near initialization for 'add_llc.hd') [-Wmissing-braces]
net/smc/smc_llc.c: In function 'smc_llc_srv_delete_link_local':
net/smc/smc_llc.c:1245:9: warning: missing braces around initializer [-Wmissing-braces]
  struct smc_llc_msg_del_link del_llc = {0};
         ^
net/smc/smc_llc.c:1245:9: warning: (near initialization for 'del_llc.hd') [-Wmissing-braces]

2 warnings generated

Fixes: 4dadd151 ("net/smc: enqueue local LLC messages")
Signed-off-by: NPujin Shi <shipujin.t@gmail.com>
Acked-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

For older versions of gcc, the array = {0}; will cause warnings:

net/smc/smc_llc.c: In function 'smc_llc_send_link_delete_all':
net/smc/smc_llc.c:1317:9: warning: missing braces around initializer [-Wmissing-braces]
  struct smc_llc_msg_del_link delllc = {0};
         ^
net/smc/smc_llc.c:1317:9: warning: (near initialization for 'delllc.hd') [-Wmissing-braces]

1 warnings generated

Fixes: f3811fd7 ("net/smc: send DELETE_LINK, ALL message and wait for send to complete")
Signed-off-by: NPujin Shi <shipujin.t@gmail.com>
Acked-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Older SMCR implementations had no link failover support and used one
link only. Because the handshake protocol requires to try the
establishment of a second link the old code sent a fake add_link message
and declined any server response afterwards.
The current code supports multiple links and inspects the received fake
add_link message more closely. To tolerate the fake add_link messages
smc_llc_is_local_add_link() needs an improved check of the message to
be able to separate between locally enqueued and fake add_link messages.
And smc_llc_cli_add_link() needs to check if the provided qp_mtu size is
invalid and reject the add_link request in that case.

Fixes: c48254fa ("net/smc: move add link processing for new device into llc layer")
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The dma related ...sync_sg... functions check the link state before the
dma function is actually called. But the check in smc_link_usable()
allows links in ACTIVATING state which are not yet mapped to dma memory.
Under high load it may happen that the sync_sg functions are called for
such a link which results in an debug output like
   DMA-API: mlx5_core 0002:00:00.0: device driver tries to sync
   DMA memory it has not allocated [device address=0x0000000103370000]
   [size=65536 bytes]
To fix that introduce a helper to check for the link state ACTIVE and
use it where appropriate. And move the link state update to ACTIVATING
to the end of smcr_link_init() when most initial setup is done.
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Fixes: d854fcbf ("net/smc: add new link state and related helpers")
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As smc client the delete link requests are assigned to the flow when
_any_ flow is active. This may break other flows that do not expect
delete link requests during their handling. Fix that by assigning the
request only when an add link flow is active. With that fix the code
for smc client and smc server is the same, so remove the separate
handling.
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Fixes: 9ec6bf19 ("net/smc: llc_del_link_work and use the LLC flow for delete link")
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a new ib device is up smc will send an add link invitation to the
peer if needed. This is currently done with rudimentary flow control.
Under high workload these add link invitations can disturb other llc
flows because they arrive unexpected. Fix this by integrating the
invitations into the normal llc event flow and handle them as a flow.
While at it, check for already assigned requests in the flow before
the new add link request is assigned.
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Fixes: 1f90a05d ("net/smc: add smcr_port_add() and smcr_link_up() processing")
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To be save from unexpected or late llc response messages check if the
arrived message fits to the current flow type and drop out-of-flow
messages. And drop it when there is already a response assigned to
the flow.
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Fixes: ef79d439 ("net/smc: process llc responses in tasklet context")
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A delete link could arrive during confirm link processing. Handle this
situation directly in smc_llc_srv_conf_link() rather than using the
logic in smc_llc_wait() to avoid the unexpected message handling there.
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Fixes: 1551c95b ("net/smc: final part of add link processing as SMC server")
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Wait for pending sends only when smc_switch_conns() found a link to move
the connections to. Do not wait during link freeing, this can lead to
permanent hang situations. And refuse to provide a new tx slot on an
unusable link.

Fixes: c6f02ebe ("net/smc: switch connections to alternate link")
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There might be races in scenarios where both SMC link groups are on the
same system. Prevent that by creating separate wait queues for LLC flows
and messages. Switch to non-interruptable versions of wait_event() and
wake_up() for the llc flow waiter to make sure the waiters get control
sequentially. Fine tune the llc_flow_lock to include the assignment of
the message. Write to system log when an unexpected message was
dropped. And remove an extra indirection and use the existing local
variable lgr in smc_llc_enqueue().

Fixes: 555da9af ("net/smc: add event-based llc_flow framework")
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixes gcc '-Wunused-but-set-variable' warning:

net/smc/smc_llc.c: In function 'smc_llc_cli_conf_link':
net/smc/smc_llc.c:753:31: warning:
 variable 'del_llc' set but not used [-Wunused-but-set-variable]
  struct smc_llc_msg_del_link *del_llc;
                               ^
net/smc/smc_llc.c: In function 'smc_llc_process_srv_delete_link':
net/smc/smc_llc.c:1311:33: warning:
 variable 'del_llc_resp' set but not used [-Wunused-but-set-variable]
    struct smc_llc_msg_del_link *del_llc_resp;
                                 ^
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Print to system log when SMC links are available or go down, link group
state changes or pnetids are applied to and removed from devices.
The log entries are triggered by either user configuration actions or
adapter activation/deactivation events and are not expected to happen
often. The entries help SMC users to keep track of the SMC link group
status and to detect when actions are needed (like to add replacements
for failed adapters).
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

During SMC-R link establishment the peers exchange the link_uid that
is used for debugging purposes. Save the peer link_uid in smc_link so it
can be retrieved by the smc_diag netlink interface.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The link_uid of an SMC-R link is exchanged between SMC peers and its
value can be used for debugging purposes. Create a unique link_uid
during link initialization and use it in communication with SMC-R peers.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow to set the reason code for the link group termination, and set
meaningful values before termination processing is triggered. This
reason code is sent to the peer in the final delete link message.
When the LLC request or response layer receives a message type that was
not handled, drop a warning and terminate the link group.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

New connections must not be assigned to asymmetric links. Add asymmetric
link tagging using new link variable link_is_asym. The new helpers
smcr_lgr_set_type() and smcr_lgr_set_type_asym() are called to set the
state of the link group, and tag all links accordingly.
smcr_lgr_conn_assign_link() respects the link tagging and will not
assign new connections to links tagged as asymmetric link.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add smc_llc_send_message_wait() which uses smc_wr_tx_send_wait() to send
an LLC message and waits for the message send to complete.
smc_llc_send_link_delete_all() calls the new function to send an
DELETE_LINK,ALL LLC message. The RFC states that the sender of this type
of message needs to wait for the completion event of the message
transmission and can terminate the link afterwards.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add smc_switch_conns() to switch all connections from a link that is
going down. Find an other link to switch the connections to, and
switch each connection to the new link. smc_switch_cursor() updates the
cursors of a connection to the state of the last successfully sent CDC
message. When there is no link to switch to, terminate the link group.
Call smc_switch_conns() when a link is going down.
And with the possibility that links of connections can switch adapt CDC
and TX functions to detect and handle link switches.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As SMC server, when a second link was deleted, trigger the setup of an
asymmetric link. Do this by enqueueing a local ADD_LINK message which
is processed by the LLC layer as if it were received from peer. Do the
same when a new IB port became active and a new link could be created.
smc_llc_srv_add_link_local() enqueues a local ADD_LINK message.
And smc_llc_srv_delete_link_local() is used the same way to enqueue a
local DELETE_LINK message. This is used when an IB port is no longer
active.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add smc_llc_process_srv_delete_link() to process a DELETE_LINK request
as SMC server. When the request is to delete ALL links then terminate
the whole link group. If not, find the link to delete by its link_id,
send the DELETE_LINK request LLC message and wait for the response.
No matter if a response was received, clear the deleted link and update
the link group state.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add smc_llc_process_cli_delete_link() to process a DELETE_LINK request
as SMC client. When the request is to delete ALL links then terminate
the whole link group. If not, find the link to delete by its link_id,
send the DELETE_LINK response LLC message and then clear the deleted
link. Finally determine and update the link group state.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduce a work that is scheduled when a new DELETE_LINK LLC request is
received. The work will call either the SMC client or SMC server
DELETE_LINK processing.
And use the LLC flow framework to process incoming DELETE_LINK LLC
messages, scheduling the llc_del_link_work for those events.
With these changes smc_lgr_forget() is only called by one function and
can be migrated into smc_lgr_cleanup_early().
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a link group moved from asymmetric to symmetric state then the
dangling asymmetric link can be deleted. Add smc_llc_find_asym_link() to
find the respective link and add smc_llc_delete_asym_link() to delete
it.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch finalizes the ADD_LINK processing of new links. Send the
CONFIRM_LINK request to the peer, receive the response and set link
state to ACTIVE.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Part of SMC server new link establishment is the exchange of rkeys for
used buffers.
Loop over all used RMB buffers and send ADD_LINK_CONTINUE LLC messages
to the peer.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

First set of functions to process an ADD_LINK LLC request as an SMC
server. Find an alternate IB device, determine the new link group type
and get the index for the new link. Then initialize the link and send
the ADD_LINK LLC message to the peer. Save the contents of the response,
ready the link, map all used buffers and register the buffers with the
IB device. If any error occurs, stop the processing and clear the link.
And call smc_llc_srv_add_link() in af_smc.c to start second link
establishment after the initial link of a link group was created.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch finalizes the ADD_LINK processing of new links. Receive the
CONFIRM_LINK request from peer, complete the link initialization,
register all used buffers with the IB device and finally send the
CONFIRM_LINK response, which completes the ADD_LINK processing.
And activate smc_llc_cli_add_link() in af_smc.c.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Part of the SMC client new link establishment process is the exchange of
rkeys for all used buffers.
Add new LLC message type ADD_LINK_CONTINUE which is used to exchange
rkeys of all current RMB buffers. Add functions to iterate over all
used RMB buffers of the link group, and implement the ADD_LINK_CONTINUE
processing.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

First set of functions to process an ADD_LINK LLC request as an SMC
client. Find an alternate IB device, determine the new link group type
and get the index for the new link. Then ready the link, map the buffers
and send an ADD_LINK LLC response. If any error occurs, send a reject
LLC message and terminate the processing.
Add smc_llc_alloc_alt_link() to find a free link index for a new link,
depending on the new link group type.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/smc/smc_llc.c:544:12: warning: ‘smc_llc_alloc_alt_link’ defined but not used [-Wunused-function]
 static int smc_llc_alloc_alt_link(struct smc_link_group *lgr,
            ^~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduce a work that is scheduled when a new ADD_LINK LLC request is
received. The work will call either the SMC client or SMC server
ADD_LINK processing.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add smc_llc_alloc_alt_link() to find a free link index for a new link,
depending on the new link group type. And update constants for the
maximum number of links to 3 (2 symmetric and 1 dangling asymmetric link).
These maximum numbers are the same as used by other implementations of the
SMC-R protocol.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the introduced link down processing in all places where the link
group is terminated and take down the affected link only.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduce llc_conf_mutex in the link group which is used to protect the
buffers and lgr states against parallel link reconfiguration.
This ensures that new connections do not start to register buffers with
the links of a link group when link creation or termination is running.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

All LLC sends are done from worker context only, so remove the prep
functions which were used to build the message before it was sent, and
add the function content into the respective send function
smc_llc_send_add_link() and smc_llc_send_delete_link().
Extend smc_llc_send_add_link() to include the qp_mtu value in the LLC
message, which is needed to establish a link after the initial link was
created. Extend smc_llc_send_delete_link() to contain a link_id and a
reason code for the link deletion in the LLC message, which is needed
when a specific link should be deleted.
And add the list of existing DELETE_LINK reason codes.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The connection layer in af_smc.c is now using the new LLC flow
framework, which made the link state DELETING obsolete. Remove the state
and the respective helpers.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The new SMC-R multiple link support will support a maximum of 3 links,
and one CONFIRM_RKEY LLC message can transport 3 rkeys of an rmb buffer.
There is no need for the LLC message type CONFIRM_RKEY_CONTINUE which is
needed when more than 3 rkeys per rmb buffer needs to be exchanged.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the LLC flow framework for the processing of DELETE_RKEY messages
that were received from the peer.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the LLC flow framework for the processing of CONFIRM_RKEY messages
that were received from the peer.
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>