linux.git/fs/dlm/lowcomms.c, branch v4.4.69

dlm: free workqueues after the connections

2016-10-22T10:26:56+00:00

commit 3a8db79889ce16930aff19b818f5b09651bb7644 upstream.

After backporting commit ee44b4bc054a ("dlm: use sctp 1-to-1 API")
series to a kernel with an older workqueue which didn't use RCU yet, it
was noticed that we are freeing the workqueues in dlm_lowcomms_stop()
too early as free_conn() will try to access that memory for canceling
the queued works if any.

This issue was introduced by commit 0d737a8cfd83 as before it such
attempt to cancel the queued works wasn't performed, so the issue was
not present.

This patch fixes it by simply inverting the free order.

Fixes: 0d737a8cfd83 ("dlm: fix race while closing connections")
Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland 
Signed-off-by: Greg Kroah-Hartman

net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA

2015-12-01T20:45:05+00:00

This patch is a cleanup to make following patch easier to
review.

Goal is to move SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA
from (struct socket)->flags to a (struct socket_wq)->flags
to benefit from RCU protection in sock_wake_async()

To ease backports, we rename both constants.

Two new helpers, sk_set_bit(int nr, struct sock *sk)
and sk_clear_bit(int net, struct sock *sk) are added so that
following patch can change their implementation.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

dlm: print error from kernel_sendpage

2015-08-27T14:34:47+00:00

Print a dlm-specific error when a socket error occurs
when sending a dlm message.

Signed-off-by: Bob Peterson 
Signed-off-by: David Teigland

dlm: sctp_accept_from_sock() can be static

2015-08-17T21:23:09+00:00

Signed-off-by: Fengguang Wu 
Signed-off-by: David Teigland

dlm: fix reconnecting but not sending data

2015-08-17T21:22:21+00:00

There are cases on which lowcomms_connect_sock() is called directly,
which caused the CF_WRITE_PENDING flag to not bet set upon reconnect,
specially on send_to_sock() error handling. On this last, the flag was
already cleared and no further attempt on transmitting would be done.

As dlm tends to connect when it needs to transmit something, it makes
sense to always mark this flag right after the connect.

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland

dlm: replace BUG_ON with a less severe handling

2015-08-17T21:22:21+00:00

BUG_ON() is a severe action for this case, specially now that DLM with
SCTP will use 1 socket per association. Instead, we can just close the
socket on this error condition and return from the function.

Also move the check to an earlier stage as it won't change and thus we
can abort as soon as possible.

Although this issue was reported when still using SCTP with 1-to-many
API, this cleanup wouldn't be that simple back then because we couldn't
close the socket and making sure such event would cease would be hard.
And actually, previous code was closing the association, yet SCTP layer
is still raising the new data event. Probably a bug to be fixed in SCTP.

Reported-by: 
Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland

dlm: use sctp 1-to-1 API

2015-08-17T21:22:20+00:00

DLM is using 1-to-many API but in a 1-to-1 fashion. That is, it's not
needed but this causes it to use sctp_do_peeloff() to mimic an
kernel_accept() and this causes a symbol dependency on sctp module.

By switching it to 1-to-1 API we can avoid this dependency and also
reduce quite a lot of SCTP-specific code in lowcomms.c.

The caveat is that now DLM won't always use the same src port. It will
choose a random one, just like TCP code. This allows the peers to
attempt simultaneous connections, which now are handled just like for
TCP.

Even more sharing between TCP and SCTP code on DLM is possible, but it
is intentionally left for a later commit.

Note that for using nodes with this commit, you have to have at least
the early fixes on this patchset otherwise it will trigger some issues
on old nodes.

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland

dlm: fix not reconnecting on connecting error handling

2015-08-17T21:22:19+00:00

If we don't clear that bit, lowcomms_connect_sock() will not schedule
another attempt, and no further attempt will be done.

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland

dlm: fix race while closing connections

2015-08-17T21:22:19+00:00

When a connection have issues DLM may need to close it.  Therefore we
should also cancel pending workqueues for such connection at that time,
and not just when dlm is not willing to use this connection anymore.

Also, if we don't clear CF_CONNECT_PENDING flag, the error handling
routines won't be able to re-connect as lowcomms_connect_sock() will
check for it.

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland

dlm: fix connection stealing if using SCTP

2015-08-17T21:22:15+00:00

When using SCTP and accepting a new connection, DLM currently validates
if the peer trying to connect to it is one of the cluster nodes, but it
doesn't check if it already has a connection to it or not.

If it already had a connection, it will be overwritten, and the new one
will be used for writes, possibly causing the node to leave the cluster
due to communication breakage.

Still, one could DoS the node by attempting N connections and keeping
them open.

As said, but being explicit, both situations are only triggerable from
other cluster nodes, but are doable with only user-level perms.

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David Teigland