linux-toradex.git/kernel/slow-work.c, branch imx-android-r10.4

slow-work: use get_ref wrapper instead of directly calling get_ref

2010-03-29T16:13:30+00:00

Otherwise we can get an oops if the user has no get_ref/put_ref
requirement.

Signed-off-by: Dave Airlie 
Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl-2.6

2009-12-08T15:38:50+00:00

* git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl-2.6: (43 commits)
  security/tomoyo: Remove now unnecessary handling of security_sysctl.
  security/tomoyo: Add a special case to handle accesses through the internal proc mount.
  sysctl: Drop & in front of every proc_handler.
  sysctl: Remove CTL_NONE and CTL_UNNUMBERED
  sysctl: kill dead ctl_handler definitions.
  sysctl: Remove the last of the generic binary sysctl support
  sysctl net: Remove unused binary sysctl code
  sysctl security/tomoyo: Don't look at ctl_name
  sysctl arm: Remove binary sysctl support
  sysctl x86: Remove dead binary sysctl support
  sysctl sh: Remove dead binary sysctl support
  sysctl powerpc: Remove dead binary sysctl support
  sysctl ia64: Remove dead binary sysctl support
  sysctl s390: Remove dead sysctl binary support
  sysctl frv: Remove dead binary sysctl support
  sysctl mips/lasat: Remove dead binary sysctl support
  sysctl drivers: Remove dead binary sysctl support
  sysctl crypto: Remove dead binary sysctl support
  sysctl security/keys: Remove dead binary sysctl support
  sysctl kernel: Remove binary sysctl logic
  ...

SLOW_WORK: Move slow_work's proc file to debugfs

2009-12-01T16:20:31+00:00

Move slow_work's debugging proc file to debugfs.

Signed-off-by: David Howells 
Requested-and-acked-by: Ingo Molnar 
Signed-off-by: Linus Torvalds

SLOW_WORK: Fix the CONFIG_MODULES=n case

2009-12-01T15:35:11+00:00

Commits 3d7a641 ("SLOW_WORK: Wait for outstanding work items belonging to a
module to clear") introduced some code to make sure that all of a module's
slow-work items were complete before that module was removed, and commit
3bde31a ("SLOW_WORK: Allow a requeueable work item to sleep till the thread is
needed") further extended that, breaking it in the process if CONFIG_MODULES=n:

    CC      kernel/slow-work.o
  kernel/slow-work.c: In function 'slow_work_execute':
  kernel/slow-work.c:313: error: 'slow_work_thread_processing' undeclared (first use in this function)
  kernel/slow-work.c:313: error: (Each undeclared identifier is reported only once
  kernel/slow-work.c:313: error: for each function it appears in.)
  kernel/slow-work.c: In function 'slow_work_wait_for_items':
  kernel/slow-work.c:950: error: 'slow_work_unreg_sync_lock' undeclared (first use in this function)
  kernel/slow-work.c:951: error: 'slow_work_unreg_wq' undeclared (first use in this function)
  kernel/slow-work.c:961: error: 'slow_work_unreg_work_item' undeclared (first use in this function)
  kernel/slow-work.c:974: error: 'slow_work_unreg_module' undeclared (first use in this function)
  kernel/slow-work.c:977: error: 'slow_work_thread_processing' undeclared (first use in this function)
  make[1]: *** [kernel/slow-work.o] Error 1

Fix this by:

 (1) Extracting the bits of slow_work_execute() that are contingent on
     CONFIG_MODULES, and the bits that should be, into inline functions and
     placing them into the #ifdef'd section that defines the relevant variables
     and adding stubs for moduleless kernels.  This allows the removal of some
     #ifdefs.

 (2) #ifdef'ing out the contents of slow_work_wait_for_items() in moduleless
     kernels.

The four functions related to handling module unloading synchronisation (and
their associated variables) could be offloaded into a separate .c file, but
each function is only used once and three of them are tiny, so doing so would
prevent them from being inlined.

Reported-by: Ingo Molnar 
Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

SLOW_WORK: Allow a requeueable work item to sleep till the thread is needed

2009-11-19T18:10:57+00:00

Add a function to allow a requeueable work item to sleep till the thread
processing it is needed by the slow-work facility to perform other work.

Sometimes a work item can't progress immediately, but must wait for the
completion of another work item that's currently being processed by another
slow-work thread.

In some circumstances, the waiting item could instead - theoretically - put
itself back on the queue and yield its thread back to the slow-work facility,
thus waiting till it gets processing time again before attempting to progress.
This would allow other work items processing time on that thread.

However, this only works if there is something on the queue for it to queue
behind - otherwise it will just get a thread again immediately, and will end
up cycling between the queue and the thread, eating up valuable CPU time.

So, slow_work_sleep_till_thread_needed() is provided such that an item can put
itself on a wait queue that will wake it up when the event it is actually
interested in occurs, then call this function in lieu of calling schedule().

This function will then sleep until either the item's event occurs or another
work item appears on the queue.  If another work item is queued, but the
item's event hasn't occurred, then the work item should requeue itself and
yield the thread back to the slow-work facility by returning.

This can be used by CacheFiles for an object that is being created on one
thread to wait for an object being deleted on another thread where there is
nothing on the queue for the creation to go and wait behind.  As soon as an
item appears on the queue that could be given thread time instead, CacheFiles
can stick the creating object back on the queue and return to the slow-work
facility - assuming the object deletion didn't also complete.

Signed-off-by: David Howells

SLOW_WORK: Allow the work items to be viewed through a /proc file

2009-11-19T18:10:51+00:00

Allow the executing and queued work items to be viewed through a /proc file
for debugging purposes.  The contents look something like the following:

    THR PID   ITEM ADDR        FL MARK  DESC
    === ===== ================ == ===== ==========
      0  3005 ffff880023f52348  a 952ms FSC: OBJ17d3: LOOK
      1  3006 ffff880024e33668  2 160ms FSC: OBJ17e5 OP60d3b: Write1/Store fl=2
      2  3165 ffff8800296dd180  a 424ms FSC: OBJ17e4: LOOK
      3  4089 ffff8800262c8d78  a 212ms FSC: OBJ17ea: CRTN
      4  4090 ffff88002792bed8  2 388ms FSC: OBJ17e8 OP60d36: Write1/Store fl=2
      5  4092 ffff88002a0ef308  2 388ms FSC: OBJ17e7 OP60d2e: Write1/Store fl=2
      6  4094 ffff88002abaf4b8  2 132ms FSC: OBJ17e2 OP60d4e: Write1/Store fl=2
      7  4095 ffff88002bb188e0  a 388ms FSC: OBJ17e9: CRTN
    vsq     - ffff880023d99668  1 308ms FSC: OBJ17e0 OP60f91: Write1/EnQ fl=2
    vsq     - ffff8800295d1740  1 212ms FSC: OBJ16be OP4d4b6: Write1/EnQ fl=2
    vsq     - ffff880025ba3308  1 160ms FSC: OBJ179a OP58dec: Write1/EnQ fl=2
    vsq     - ffff880024ec83e0  1 160ms FSC: OBJ17ae OP599f2: Write1/EnQ fl=2
    vsq     - ffff880026618e00  1 160ms FSC: OBJ17e6 OP60d33: Write1/EnQ fl=2
    vsq     - ffff880025a2a4b8  1 132ms FSC: OBJ16a2 OP4d583: Write1/EnQ fl=2
    vsq     - ffff880023cbe6d8  9 212ms FSC: OBJ17eb: LOOK
    vsq     - ffff880024d37590  9 212ms FSC: OBJ17ec: LOOK
    vsq     - ffff880027746cb0  9 212ms FSC: OBJ17ed: LOOK
    vsq     - ffff880024d37ae8  9 212ms FSC: OBJ17ee: LOOK
    vsq     - ffff880024d37cb0  9 212ms FSC: OBJ17ef: LOOK
    vsq     - ffff880025036550  9 212ms FSC: OBJ17f0: LOOK
    vsq     - ffff8800250368e0  9 212ms FSC: OBJ17f1: LOOK
    vsq     - ffff880025036aa8  9 212ms FSC: OBJ17f2: LOOK

In the 'THR' column, executing items show the thread they're occupying and
queued threads indicate which queue they're on.  'PID' shows the process ID of
a slow-work thread that's executing something.  'FL' shows the work item flags.
'MARK' indicates how long since an item was queued or began executing.  Lastly,
the 'DESC' column permits the owner of an item to give some information.

Signed-off-by: David Howells

SLOW_WORK: Add delayed_slow_work support

2009-11-19T18:10:47+00:00

This adds support for starting slow work with a delay, similar
to the functionality we have for workqueues.

Signed-off-by: Jens Axboe 
Signed-off-by: David Howells

SLOW_WORK: Add support for cancellation of slow work

2009-11-19T18:10:43+00:00

Add support for cancellation of queued slow work and delayed slow work items.
The cancellation functions will wait for items that are pending or undergoing
execution to be discarded by the slow work facility.

Attempting to enqueue work that is in the process of being cancelled will
result in ECANCELED.

Signed-off-by: Jens Axboe 
Signed-off-by: David Howells

SLOW_WORK: Make slow_work_ops ->get_ref/->put_ref optional

2009-11-19T18:10:39+00:00

Make the ability for the slow-work facility to take references on a work item
optional as not everyone requires this.

Even the internal slow-work stubs them out, so those can be got rid of too.

Signed-off-by: Jens Axboe 
Signed-off-by: David Howells

SLOW_WORK: Wait for outstanding work items belonging to a module to clear

2009-11-19T18:10:23+00:00

Wait for outstanding slow work items belonging to a module to clear when
unregistering that module as a user of the facility.  This prevents the put_ref
code of a work item from being taken away before it returns.

Signed-off-by: David Howells