linux-toradex.git/fs/dlm/lowcomms.c, branch v3.0.29

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

dlm: use alloc_workqueue function

2011-03-10T19:22:34+00:00

Replaces deprecated create_singlethread_workqueue().

Signed-off-by: David Teigland

dlm: use single thread workqueues

2011-02-11T22:50:47+00:00

The recent commit to use cmwq for send and recv threads
dcce240ead802d42b1e45ad2fcb2ed4a399cb255 introduced problems,
apparently due to multiple workqueue threads.  Single threads
make the problems go away, so return to that until we fully
understand the concurrency issues with multiple threads.

Signed-off-by: David Teigland

dlm: sanitize work_start() in lowcomms.c

2010-12-13T19:42:24+00:00

The create_workqueue() returns NULL if failed rather than ERR_PTR().
Fix error checking and remove unnecessary variable 'error'.

Signed-off-by: Namhyung Kim 
Cc: Tejun Heo 
Signed-off-by: David Teigland

dlm: reduce cond_resched during send

2010-11-12T17:15:20+00:00

Calling cond_resched() after every send can unnecessarily
degrade performance.  Go back to an old method of scheduling
after 25 messages.

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

dlm: use TCP_NODELAY

2010-11-12T17:12:55+00:00

Nagling doesn't help and can sometimes hurt dlm comms.

Signed-off-by: David Teigland

dlm: Use cmwq for send and receive workqueues

2010-11-12T17:08:03+00:00

So far as I can tell, there is no reason to use a single-threaded
send workqueue for dlm, since it may need to send to several sockets
concurrently. Both workqueues are set to WQ_MEM_RECLAIM to avoid
any possible deadlocks, WQ_HIGHPRI since locking traffic is highly
latency sensitive (and to avoid a priority inversion wrt GFS2's
glock_workqueue) and WQ_FREEZABLE just in case someone needs to do
that (even though with current cluster infrastructure, it doesn't
make sense as the node will most likely land up ejected from the
cluster) in the future.

Signed-off-by: Steven Whitehouse 
Cc: Tejun Heo 
Signed-off-by: David Teigland

dlm: Handle application limited situations properly.

2010-11-11T19:05:12+00:00

In the normal regime where an application uses non-blocking I/O
writes on a socket, they will handle -EAGAIN and use poll() to
wait for send space.

They don't actually sleep on the socket I/O write.

But kernel level RPC layers that do socket I/O operations directly
and key off of -EAGAIN on the write() to "try again later" don't
use poll(), they instead have their own sleeping mechanism and
rely upon ->sk_write_space() to trigger the wakeup.

So they do effectively sleep on the write(), but this mechanism
alone does not let the socket layers know what's going on.

Therefore they must emulate what would have happened, otherwise
TCP cannot possibly see that the connection is application window
size limited.

Handle this, therefore, like SUNRPC by setting SOCK_NOSPACE and
bumping the ->sk_write_count as needed when we hit the send buffer
limits.

This should make TCP send buffer size auto-tuning and the
->sk_write_space() callback invocations actually happen.

Signed-off-by: David S. Miller 
Signed-off-by: David Teigland

fs/dlm: Drop unnecessary null test

2010-08-05T19:23:45+00:00

hlist_for_each_entry binds its first argument to a non-null value, and thus
any null test on the value of that argument is superfluous.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// 
@@
iterator I;
expression x,E,E1,E2;
statement S,S1,S2;
@@

I(x,...) { <...
- (x != NULL) &&
  E
  ...> }
// 

Signed-off-by: Julia Lawall 
Signed-off-by: David Teigland

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32+00:00

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo 
Guess-its-ok-by: Christoph Lameter 
Cc: Ingo Molnar 
Cc: Lee Schermerhorn