Commit graph

106 commits

Author SHA1 Message Date
Alexander Aring
541adb0d4d fs: dlm: debugfs for queued callbacks
It was useful to debug an issue with the callback queue to check if any
callbacks in any lkb are for some reason not processed by the callback
workqueue. The mentioned issue was fixed by commit a034c1370d ("fs:
dlm: fix DLM_IFL_CB_PENDING gets overwritten"). If there are similar
issue that looks like a ast callback was not processed, we can confirm
now that it is not sitting to be processed by the callback workqueue
anymore.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-08-10 10:33:03 -05:00
Alexander Aring
75a7d60134 fs: dlm: handle lkb wait count as atomic_t
Currently the lkb_wait_count is locked by the rsb lock and it should be
fine to handle lkb_wait_count as non atomic_t value. However for the
overall process of reducing locking this patch converts it to an
atomic_t value.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-06-14 10:17:33 -05:00
Alexander Aring
1361737f10 fs: dlm: switch lkb_sbflags to atomic ops
This patch moves lkb_sbflags handling to atomic bits ops. This should
prepare for a possible manipulating of lkb_sbflags flags at the same
time by concurrent execution.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
46d6e722d8 fs: dlm: rsb hash table flag value to atomic ops
This patch moves the rsb hash table handling to atomic flag operations.
The flag operations for DLM_RTF_SHRINK are protected by
ls->ls_rsbtbl[b].lock. However we switch to atomic ops if new possible
flags will be used in a different way and don't assume such lock
dependencies.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
e1af8728f6 fs: dlm: move internal flags to atomic ops
This patch will move the lkb_flags value to the recently introduced
lkb_iflags value. For lkb_iflags we use atomic bit operations because
some flags like DLM_IFL_CB_PENDING are used while non rsb lock is held
to avoid issues with other flag manipulations which might run at the
same time we switch to atomic bit operations. Snapshot the bit values to
an uint32_t value is only used for debugging/logging use cases and don't
need to be 100% correct.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
8a39dcd9c3 fs: dlm: change dflags to use atomic bits
Currently manipulating lkb_dflags assumes to held the rsb lock assigned
to the lkb. This is held by dlm message processing after certain
time to lookup the right rsb from the received lkb message id. For user
space locks flags, which is currently the only use case for lkb_dflags,
flags are also being set during dlm character device handling without
holding the rsb lock. To minimize the risk that bit operations are
getting corrupted we switch to atomic bit operations. This patch will
also introduce helpers to snapshot atomic bit values in an non atomic
way. There might be still issues with the flag handling e.g. running in
case of manipulating bit ops and snapshot them at the same time, but this
patch minimize them and will start to use atomic bit operations.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
8c11ba64ce fs: dlm: store lkb distributed flags into own value
This patch stores lkb distributed flags value in an separate value
instead of sharing internal and distributed flags in lkb->lkb_flags value.
This has the advantage to not mask/write back flag values in
receive_flags() functionality. The dlm debug_fs does not provide the
distributed flags anymore, those can be added in future.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
9f48eead5e fs: dlm: remove DLM_IFL_LOCAL_MS flag
The DLM_IFL_LOCAL_MS flag is an internal non shared flag but used in
m_flags of dlm messages. It is not shared because it is only used for
local messaging. Instead using DLM_IFL_LOCAL_MS in dlm messages we pass a
parameter around to signal local messaging or not. This patch is adding
the local parameter to signal local messaging.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
a7e7ffacad fs: dlm: rename stub to local message flag
This patch renames DLM_IFL_STUB_MS to DLM_IFL_LOCAL_MS flag. The
DLM_IFL_STUB_MS flag is somewhat misnamed, it means the dlm message is
used for local message transfer only. It is used by recovery to resolve
lock states if a node got fenced.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
01c7a59789 fs: dlm: remove deprecated code parts
This patch removes code parts which was declared deprecated by
commit 6b0afc0cc3 ("fs: dlm: don't use deprecated timeout features by
default"). This contains the following dlm functionality:

- start a cancel of a dlm request did not complete after certain timeout:
  The current way how dlm cancellation works and interfering with other
  dlm requests triggered by the user can end in an overlapping and
  returning in -EBUSY. The most user don't handle this case and are
  unaware that DLM can return such errno in such situation. Due the
  timeout the user are mostly unaware when this happens.
- start a netlink warning messages for user space if dlm requests did
  not complete after certain timeout:
  This feature was never being built in the only known dlm user space side.
  As we are to remove the timeout cancellation feature we can directly
  remove this feature as well.

There might be the possibility to bring the timeout cancellation feature
back. However the current way of handling the -EBUSY case which is only
a software limitation and not a hardware limitation should be changed.
We minimize the current code base in DLM cancellation feature to not have
to deal with those existing features while solving the DLM cancellation
feature in general.

UAPI define DLM_LSFL_TIMEWARN is commented as deprecated and reserved
value. We should avoid at first to give it a new meaning but let
possible users still compile by keeping this define. In far future we
can give this flag a new meaning. The same for the DLM_LKF_TIMEOUT lock
request flag.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
a034c1370d fs: dlm: fix DLM_IFL_CB_PENDING gets overwritten
This patch introduce a new internal flag per lkb value to handle
internal flags which are handled not on wire. The current lkb internal
flags stored as lkb->lkb_flags are split in upper and lower bits, the
lower bits are used to share internal flags over wire for other cluster
wide lkb copies on other nodes.

In commit 61bed0baa4 ("fs: dlm: use a non-static queue for callbacks")
we introduced a new internal flag for pending callbacks for the dlm
callback queue. This flag is protected by the lkb->lkb_cb_lock lock.
This patch overlooked that on dlm receive path and the mentioned upper
and lower bits, that dlm will read the flags, mask it and write it
back. As example receive_flags() in fs/dlm/lock.c. This flag
manipulation is not done atomically and is not protected by
lkb->lkb_cb_lock. This has unknown side effects of the current callback
handling.

In future we should move to set/clear/test bit functionality and avoid
read, mask and writing back flag values. In later patches we will move
the upper parts to the new introduced internal lkb flags which are not
shared between other cluster nodes to the new non shared internal flag
field to avoid similar issues.

Cc: stable@vger.kernel.org
Fixes: 61bed0baa4 ("fs: dlm: use a non-static queue for callbacks")
Reported-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-03-06 15:49:07 -06:00
Alexander Aring
554d849616 fs: dlm: rename DLM_IFL_NEED_SCHED to DLM_IFL_CB_PENDING
This patch renames DLM_IFL_NEED_SCHED to DLM_IFL_CB_PENDING because
CB_PENDING is a proper name to describe this flag. This flag is set when
callback enqueue will return DLM_ENQUEUE_CALLBACK_NEED_SCHED because the
callback worker need to be queued. The flag tells that callbacks are
currently pending to be called and will be unset if the callback work
for the specific lkb is done. The term need schedule is part of this
time but a proper name is to say that there are some callbacks pending
to being called.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-11-21 09:45:49 -06:00
Alexander Aring
3872f87b09 fs: dlm: remove ls_remove_wait waitqueue
This patch removes the ls_remove_wait waitqueue handling. The current
handling tries to wait before a lookup is send out for a identically
resource name which is going to be removed. Hereby the remove message
should be send out before the new lookup message. The reason is that
after a lookup request and response will actually use the specific
remote rsb. A followed remove message would delete the rsb on the remote
side but it's still being used.

To reach a similar behaviour we simple send the remove message out while
the rsb lookup lock is held and the rsb is removed from the toss list.
Other find_rsb() calls would never have the change to get a rsb back to
live while a remove message will be send out (without holding the lock).

This behaviour requires a non-sleepable context which should be provided
now and might be the reason why it was not implemented so in the first
place.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-11-08 12:59:41 -06:00
Alexander Aring
61bed0baa4 fs: dlm: use a non-static queue for callbacks
This patch will introducde a queue implementation for callbacks by using
the Linux lists. The current callback queue handling is implemented by a
static limit of 6 entries, see DLM_CALLBACKS_SIZE. The sequence number
inside the callback structure was used to see if the entries inside the
static entry is valid or not. We don't need any sequence numbers anymore
with a dynamic datastructure with grows and shrinks during runtime to
offer such functionality.

We assume that every callback will be delivered to the DLM user if once
queued. Therefore the callback flag DLM_CB_SKIP was dropped and the
check for skipping bast was moved before worker handling and not skip
while the callback worker executes. This will reduce unnecessary queues
of the callback worker.

All last callback saves are pointers now and don't need to copied over.
There is a reference counter for callback structures which will care
about to free the callback structures at the right time if they are not
referenced anymore.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-11-08 12:59:41 -06:00
Alexander Aring
92e9573330 fs: dlm: use spin lock instead of mutex
There is no need to use a mutex in those hot path sections. We change it
to spin lock to serve callbacks more faster by not allowing schedule.
The locked sections will not be locked for a long time.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-11-08 12:59:41 -06:00
Alexander Aring
a4c0352bb1 fs: dlm: convert ls_cb_mutex mutex to spinlock
This patch converts the ls_cb_mutex mutex to a spinlock, there is no
sleepable context when this lock is held.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-11-08 12:59:41 -06:00
Paulo Miguel Almeida
d96d0f9617 dlm: replace one-element array with fixed size array
One-element arrays are deprecated. So, replace one-element array with
fixed size array member in struct dlm_ls, and refactor the rest of the
code, accordingly.

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/228
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
Link: https://lore.kernel.org/lkml/Y0W5jkiXUkpNl4ap@mail.google.com/

Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-11-08 12:58:47 -06:00
Alexander Aring
296d9d1e98 fs: dlm: change ls_clear_proc_locks to spinlock
This patch changes the ls_clear_proc_locks to a spinlock because there
is no need to handle it as a mutex as there is no sleepable context when
ls_clear_proc_locks is held. This allows us to call those functionality
in non-sleepable contexts.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-08-23 14:54:02 -05:00
Alexander Aring
6b0afc0cc3 fs: dlm: don't use deprecated timeout features by default
This patch will disable use of deprecated timeout features if
CONFIG_DLM_DEPRECATED_API is not set.  The deprecated features
will be removed in upcoming kernel release v6.2.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-08-01 09:31:38 -05:00
Alexander Aring
2bb2a3d66c fs: dlm: remove waiter warnings
This patch removes warning messages that could be logged when
remote requests had been waiting on a reply message for some timeout
period (which could be set through configfs, but was rarely enabled.)
The improved midcomms layer now carefully tracks all messages and
replies, and logs much more useful messages if there is an actual
problem.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-06-24 11:57:52 -05:00
Alexander Aring
f10da927a5 fs: dlm: add comment about lkb IFL flags
This patch adds comments about the difference between the lower 2 bytes
of lkb flags and the 2 upper bytes of the lkb IFL flags. In short the
upper 2 bytes will be handled as internal flags whereas the lower 2
bytes are part of the DLM protocol and are used to exchange messages.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-06-24 11:57:49 -05:00
Alexander Aring
682bb91b6b fs: dlm: make new_lockspace() wait until recovery completes
Make dlm_new_lockspace() wait until a full recovery completes
sucessfully or fails. Previously, dlm_new_lockspace() returned
to the caller after dlm_recover_members() finished, which is
only partially through recovery.  The result of the previous
behavior is that the new lockspace would not be usable for some
time (especially with overlapping recoveries), and some errors
in the later part of recovery could not be returned to the caller.

Kernel callers gfs2 and cluster-md have their own wait handling to
wait for recovery to complete after calling dlm_new_lockspace().
This continues to work, but will be unnecessary.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-06-24 11:57:47 -05:00
Alexander Aring
00e99ccde7 dlm: use __le types for dlm messages
This patch changes to use __le types directly in the dlm message
structure which is casted at the right dlm message buffer positions.

The main goal what is reached here is to remove sparse warnings
regarding to host to little byte order conversion or vice versa. Leaving
those sparse issues ignored and always do it in out/in functionality
tends to leave it unknown in which byte order the variable is being
handled.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-04-06 14:02:37 -05:00
Alexander Aring
2f9dbeda8d dlm: use __le types for rcom messages
This patch changes to use __le types directly in the dlm rcom
structure which is casted at the right dlm message buffer positions.

The main goal what is reached here is to remove sparse warnings
regarding to host to little byte order conversion or vice versa. Leaving
those sparse issues ignored and always do it in out/in functionality
tends to leave it unknown in which byte order the variable is being
handled.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-04-06 14:02:32 -05:00
Alexander Aring
3428785a65 dlm: use __le types for dlm header
This patch changes to use __le types directly in the dlm header
structure which is casted at the right dlm message buffer positions.

The main goal what is reached here is to remove sparse warnings
regarding to host to little byte order conversion or vice versa. Leaving
those sparse issues ignored and always do it in out/in functionality
tends to leave it unknown in which byte order the variable is being
handled.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-04-06 14:02:28 -05:00
Alexander Aring
d9efd005fd dlm: use __le types for options header
This patch changes to use __le types directly in the dlm option headers
structures which are casted at the right dlm message buffer positions.

Currently only midcomms.c using those headers which already was calling
endian conversions on-the-fly without using in/out functionality like
other endianness handling in dlm. Using __le types now will hopefully get
useful warnings in future if we do comparison against host byte order
values.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2022-04-06 14:02:24 -05:00
Alexander Aring
21d9ac1a53 fs: dlm: use event based wait for pending remove
This patch will use an event based waitqueue to wait for a possible clash
with the ls_remove_name field of dlm_ls instead of doing busy waiting.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-12-07 12:42:26 -06:00
Alexander Aring
3cb5977c52 fs: dlm: ls_count busy wait to event based wait
This patch changes the ls_count busy wait to use atomic counter values
and wait_event() to wait until ls_count reach zero. It will slightly
reduce the number of holding lslist_lock. At remove lockspace we need to
retry the wait because it a lockspace get could interefere between
wait_event() and holding the lock which deletes the lockspace list entry.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-11-02 14:39:20 -05:00
Alexander Aring
164d88abd7 fs: dlm: requestqueue busy wait to event based wait
This patch changes the requestqueue busy waiting algorithm to use
atomic counter values and wait_event() to wait until the requestqueue is
empty. It will slightly reduce the number of holding ls_requestqueue_mutex
mutex.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-11-02 14:39:20 -05:00
Alexander Aring
dea450c90f fs: dlm: remove obsolete INBUF define
This patch removes an obsolete define for some length for an temporary
buffer which is not being used anymore. The use of this define is not
necessary anymore since commit 4798cbbfbd ("fs: dlm: rework receive
handling").

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-11-02 14:39:20 -05:00
Alexander Aring
b892e4792c fs: dlm: fix typo in tlv prefix
This patch fixes a small typo in a unused struct field. It should named
be t_pad instead of o_pad. Came over this as I updated wireshark
dissector.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-07-19 11:53:43 -05:00
Alexander Aring
5b2f981fde fs: dlm: add midcomms debugfs functionality
This patch adds functionality to debug midcomms per connection state
inside a comms directory which is similar like dlm configfs. Currently
there exists the possibility to read out two attributes which is the
send queue counter and the version of each midcomms node state.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-05-25 09:22:20 -05:00
Alexander Aring
489d8e559c fs: dlm: add reliable connection if reconnect
This patch introduce to make a tcp lowcomms connection reliable even if
reconnects occurs. This is done by an application layer re-transmission
handling and sequence numbers in dlm protocols. There are three new dlm
commands:

DLM_OPTS:

This will encapsulate an existing dlm message (and rcom message if they
don't have an own application side re-transmission handling). As optional
handling additional tlv's (type length fields) can be appended. This can
be for example a sequence number field. However because in DLM_OPTS the
lockspace field is unused and a sequence number is a mandatory field it
isn't made as a tlv and we put the sequence number inside the lockspace
id. The possibility to add optional options are still there for future
purposes.

DLM_ACK:

Just a dlm header to acknowledge the receive of a DLM_OPTS message to
it's sender.

DLM_FIN:

This provides a 4 way handshake for connection termination inclusive
support for half-closed connections. It's provided on application layer
because SCTP doesn't support half-closed sockets, the shutdown() call
can interrupted by e.g. TCP resets itself and a hard logic to implement
it because the othercon paradigm in lowcomms. The 4-way termination
handshake also solve problems to synchronize peer EOF arrival and that
the cluster manager removes the peer in the node membership handling of
DLM. In some cases messages can be still transmitted in this time and we
need to wait for the node membership event.

To provide a reliable connection the node will retransmit all
unacknowledges message to it's peer on reconnect. The receiver will then
filtering out the next received message and drop all messages which are
duplicates.

As RCOM_STATUS and RCOM_NAMES messages are the first messages which are
exchanged and they have they own re-transmission handling, there exists
logic that these messages must be first. If these messages arrives we
store the dlm version field. This handling is on DLM 3.1 and after this
patch 3.2 the same. A backwards compatibility handling has been added
which seems to work on tests without tcpkill, however it's not recommended
to use DLM 3.1 and 3.2 at the same time, because DLM 3.2 tries to fix long
term bugs in the DLM protocol.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-05-25 09:22:20 -05:00
Alexander Aring
8e2e40860c fs: dlm: add union in dlm header for lockspace id
This patch adds union inside the lockspace id to handle it also for
another use case for a different dlm command.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-05-25 09:22:20 -05:00
Alexander Aring
8f2dc78dbc fs: dlm: make buffer handling per msg
This patch makes the void pointer handle for lowcomms functionality per
message and not per page allocation entry. A refcount handling for the
handle was added to keep the message alive until the user doesn't need
it anymore.

There exists now a per message callback which will be called when
allocating a new buffer. This callback will be guaranteed to be called
according the order of the sending buffer, which can be used that the
caller increments a sequence number for the dlm message handle.

For transition process we cast the dlm_mhandle to dlm_msg and vice versa
until the midcomms layer will implement a specific dlm_mhandle structure.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-05-25 09:22:20 -05:00
Alexander Aring
2df6b7627a fs: dlm: add dlm macros for ratelimit log
This patch add ratelimit macro to dlm subsystem and will set the
connecting log message to ratelimit. In non blocking connecting cases it
will print out this message a lot.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-05-25 09:22:20 -05:00
Arnd Bergmann
fe204591cc dlm: remove BUG() before panic()
Building a kernel with clang sometimes fails with an objtool error in dlm:

fs/dlm/lock.o: warning: objtool: revert_lock_pc()+0xbd: can't find jump dest instruction at .text+0xd7fc

The problem is that BUG() never returns and the compiler knows
that anything after it is unreachable, however the panic still
emits some code that does not get fully eliminated.

Having both BUG() and panic() is really pointless as the BUG()
kills the current process and the subsequent panic() never hits.
In most cases, we probably don't really want either and should
replace the DLM_ASSERT() statements with WARN_ON(), as has
been done for some of them.

Remove the BUG() here so the user at least sees the panic message
and we can reliably build randconfig kernels.

Fixes: e7fd41792f ("[DLM] The core of the DLM for GFS2/CLVM")
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: clang-built-linux@googlegroups.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Teigland <teigland@redhat.com>
2020-05-12 14:06:18 -05:00
Gustavo A. R. Silva
a4e439a6f6 dlm: dlm_internal: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2020-05-12 14:06:14 -05:00
Greg Kroah-Hartman
a48f9721e6 dlm: no need to check return value of debugfs_create functions
When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Teigland <teigland@redhat.com>
2019-07-11 11:01:58 -05:00
Thomas Gleixner
2522fe45a1 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193
Based on 1 normalized pattern(s):

  this copyrighted material is made available to anyone wishing to use
  modify copy or redistribute it subject to the terms and conditions
  of the gnu general public license v 2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 45 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170027.342746075@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:29:21 -07:00
Linus Torvalds
7c0f6ba682 Replace <asm/uaccess.h> with <linux/uaccess.h> globally
This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-24 11:46:01 -08:00
Paul Gortmaker
7963b8a598 dlm: audit and remove any unnecessary uses of module.h
Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends.  That changed
when we forked out support for the latter into the export.h file.
This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig.

In the case of some code where it is modular, we can extend that to
also include files that are building basic support functionality but
not related to loading or registering the final module; such files
also have no need whatsoever for module.h

The advantage in removing such instances is that module.h itself
sources about 15 other headers; adding significantly to what we feed
cpp, and it can obscure what headers we are effectively using.

Since module.h might have been the implicit source for init.h
(for __init) and for export.h (for EXPORT_SYMBOL) we consider each
instance for the presence of either and replace as needed.

In the dlm case, we remove module.h from a global header and only
introduce it in the files where it is explicitly required, since
there is nothing modular in dlm_internal.h itself.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2016-10-19 11:00:03 -05:00
Zhilong Liu
505ee5283c dlm: add log_info config option
This config option can be used to disable the
LOG_INFO recovery messages.

Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2016-06-21 09:04:24 -05:00
David Teigland
075f01775f dlm: use INFO for recovery messages
The log messages relating to the progress of recovery
are minimal and very often useful.  Change these to
the KERN_INFO level so they are always available.

Signed-off-by: David Teigland <teigland@redhat.com>
2014-02-14 11:54:44 -06:00
David Teigland
f117228346 dlm: avoid scanning unchanged toss lists
Keep track of whether a toss list contains any
shrinkable rsbs.  If not, dlm_scand can avoid
scanning the list for rsbs to shrink.  Unnecessary
scanning can otherwise waste a lot of time because
the toss lists can contain a large number of rsbs
that are non-shrinkable (directory records).

Signed-off-by: David Teigland <teigland@redhat.com>
2013-01-07 12:02:49 -06:00
David Teigland
da8c66638a dlm: fix lvb invalidation conditions
When a node is removed that held a PW/EX lock, the
existing master node should invalidate the lvb on the
resource due to the purged lock.

Previously, the existing master node was invalidating
the lvb if it found only NL/CR locks on the resource
during recovery for the removed node.  This could lead
to cases where it invalidated the lvb and shouldn't
have, or cases where it should have invalidated and
didn't.

When recovery selects a *new* master node for a
resource, and that new master finds only NL/CR locks
on the resource after lock recovery, it should
invalidate the lvb.  This case was handled correctly
(but was incorrectly applied to the existing master
case also.)

When a process exits while holding a PW/EX lock,
the lvb on the resource should be invalidated.
This was not happening.

The lvb contents and VALNOTVALID flag should be
recovered before granting locks in recovery so that
the recovered lvb state is provided in the callback.
The lvb was being recovered after the lock was granted.

Signed-off-by: David Teigland <teigland@redhat.com>
2012-11-16 11:20:42 -06:00
David Teigland
475f230c60 dlm: fix unlock balance warnings
The in_recovery rw_semaphore has always been acquired and
released by different threads by design.  To work around
the "BUG: bad unlock balance detected!" messages, adjust
things so the dlm_recoverd thread always does both down_write
and up_write.

Signed-off-by: David Teigland <teigland@redhat.com>
2012-08-08 11:33:49 -05:00
David Teigland
05c32f47bf dlm: fix race between remove and lookup
It was possible for a remove message on an old
rsb to be sent after a lookup message on a new
rsb, where the rsbs were for the same resource
name.  This could lead to a missing directory
entry for the new rsb.

It is fixed by keeping a copy of the resource
name being removed until after the remove has
been sent.  A lookup checks if this in-progress
remove matches the name it is looking up.

Signed-off-by: David Teigland <teigland@redhat.com>
2012-07-16 14:18:01 -05:00
David Teigland
1d7c484eeb dlm: use idr instead of list for recovered rsbs
When a large number of resources are being recovered,
a linear search of the recover_list takes a long time.
Use an idr in place of a list.

Signed-off-by: David Teigland <teigland@redhat.com>
2012-07-16 14:17:52 -05:00
David Teigland
c04fecb4d9 dlm: use rsbtbl as resource directory
Remove the dir hash table (dirtbl), and use
the rsb hash table (rsbtbl) as the resource
directory.  It has always been an unnecessary
duplication of information.

This improves efficiency by using a single rsbtbl
lookup in many cases where both rsbtbl and dirtbl
lookups were needed previously.

This eliminates the need to handle cases of rsbtbl
and dirtbl being out of sync.

In many cases there will be memory savings because
the dir hash table no longer exists.

Signed-off-by: David Teigland <teigland@redhat.com>
2012-07-16 14:16:19 -05:00