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  1. 12 Nov, 2013 14 commits
    • Ian Abbott's avatar
      staging: comedi: increment reference while file open · fc406986
      Ian Abbott authored 
      In the 'open' file operation handler `comedi_open()` in "comedi_fops.c",
call `comedi_dev_get_from_minor()` instead of `comedi_dev_from_minor()`
to get the pointer to the `struct comedi_device`.  This increments the
reference to prevent it being freed.  Call `comedi_dev_put()` to
decrement the reference  on failure, and also call it from the 'release'
file operation handler `comedi_close()`.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      fc406986
    • Ian Abbott's avatar
      staging: comedi: add comedi_dev_get_from_minor() · b449c1ca
      Ian Abbott authored 
      Add function `struct comedi_device *comedi_dev_get_from_minor(unsigned
minor)`.  This behaves like the existing `comedi_dev_from_minor()`
except that it also increments the `struct kref refcount` member (via
new helper function `comedi_dev_get()`) to prevent it being freed.  If
it returns a valid pointer, the caller is responsible for calling
`comedi_dev_put()` to decrement the reference count.

Export `comedi_dev_get_from_minor()` and `comedi_dev_put()` as they will
be used by the "kcomedilib" module in addition to the "comedi" module
itself.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b449c1ca
    • Ian Abbott's avatar
      staging: comedi: add a kref to comedi device · 5b13ed94
      Ian Abbott authored 
      Add a `struct kref refcount` member to `struct comedi_device` to allow
safe destruction of the comedi device.  Only free the comedi device via
the 'release' callback `kref_put()`.  Currently, nothing calls
`kref_put()`, so the safe destruction is ineffective, but this will be
addressed by later patches.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      5b13ed94
    • Ian Abbott's avatar
      staging: comedi: protect against detach during read operation · 45c2bc55
      Ian Abbott authored 
      The 'read' file operation for comedi devices does not use the main mutex
in the `struct comedi_device` to avoid contention with some ioctls that
may take a while to complete.  Use the `attach_lock` semaphore to
protect against detachment while the 'read' operation is in progress.
This is a `struct rw_semaphore` and we read-lock it to protect against
device detachment.

Note that `comedi_device_cancel_all()` is called during device
detachment, which cancels any ongoing asynchronous commands.  This will
wake up any blocked readers which will then release the `attach_lock`
semaphore and complete the 'read' operation early.

The only time the 'read' file operation does use the main mutex is at
the end of the command when it has to call `do_become_nonbusy()` to mark
the subdevice as no longer busy handling an asynchronous command.  To
avoid deadlock, it has to remove the task from the wait queue and
release the `attach_lock` semaphore before acquiring the main mutex.  It
then needs to confirm the device is still attached.  Unfortunately, we
do not yet protect against a dynamically allocated `struct
comedi_device` being deleted during the operation.  This will be
addressed by a later patch.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      45c2bc55
    • Ian Abbott's avatar
      staging: comedi: protect against detach during write operation · 9329f139
      Ian Abbott authored 
      The 'write' file operation for comedi devices does not use the main
mutex in the `struct comedi_device` to avoid contention with some ioctls
that may take a while to complete.  Use the `attach_lock` semaphore to
protect against detachment while the 'write' operation is in progress.
This is a `struct rw_semaphore` and we read-lock it to protect against
device detachment.

Note that `comedi_device_cancel_all()` is called during device
detachment, which cancels any ongoing asynchronous commands.  This will
wake up any blocked writers which will then release the `attach_lock`
semaphore and complete the 'write' operation early.

The only time the 'write' file operation does use the main mutex is at
the end of the command when it has to call `do_become_nonbusy()` to mark
the subdevice as no longer busy handling an asynchronous command.  To
avoid deadlock, it has to remove the task from the wait queue and
release the `attach_lock` semaphore before acquiring the main mutex.  It
then needs to confirm that the device is still attached.  Unfortunately,
we do not yet protect against a dynamically allocated `struct
comedi_device` being deleted during the operation.  This will be
addressed by a later patch.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      9329f139
    • Ian Abbott's avatar
      staging: comedi: add detachment counter for validity checks · ef77c0b2
      Ian Abbott authored 
      Add a member `detach_count` to `struct comedi_device` that is
incremented every time the device gets detached.  This will be used in
some validity checks in the 'read' and 'write' file operations to make
sure the attachment remains valid.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ef77c0b2
    • Ian Abbott's avatar
      staging: comedi: cancel commands before detaching device · d19db51a
      Ian Abbott authored 
      The comedi core module's handling of the `COMEDI_DEVCONFIG` ioctl will
not allow a device to be detached if it is busy.  However, comedi
devices can also be auto-detached due to a removal of a hardware device.
One of the things we should do in that case is cancel any asynchronous
commands that are running.  Add a new function
`comedi_device_cancel_all()` to do that and call it from
`comedi_device_detach()`.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d19db51a
    • Ian Abbott's avatar
      staging: comedi: wake up async waiters when become non-busy · 8da8c86f
      Ian Abbott authored 
      Wake up all waiters on the comedi subdevice's async wait queue whenever
the subdevice is marked "non-busy".  This happens when an asynchronous
command is cancelled or when a command is terminated and all data has
been read or written.  Note: use `wake_up_interruptible_all()` as we
only use interruptible waits.

Remove the call to `wake_up_interruptible()` from `do_cancel_ioctl()` as
it will call `wake_up_interruptible_all()` indirectly via `do_cancel()`
and `do_become_nonbusy()`.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8da8c86f
    • Ian Abbott's avatar
      staging: comedi: cleanup_device() -> comedi_device_detach_cleanup() · 3867e20d
      Ian Abbott authored 
      Rename the local function `cleanup_device()` to
`comedi_device_detach_cleanup()`.  It is only called from the
`comedi_device_detach()` function and that is called from
`comedi_device_cleanup()` and other places.  The more specific function
name seems less confusing.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3867e20d
    • Ian Abbott's avatar
      staging: comedi: use attach_lock semaphore during attach and detach · bf11c134
      Ian Abbott authored 
      Acquire the `attach_lock` semaphore in the `struct comedi_device` while
modifying the `attached` flag.  This is a "write" acquire.  Note that
the main mutex in the `struct comedi_device` is also held at this time.
Tasks wishing to check the device is attached will need to either
acquire the main mutex, or "read" acquire the `attach_lock` semaphore,
or both in that order.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bf11c134
    • Ian Abbott's avatar
      staging: comedi: add rw_semaphore to protect against device detachment · 2f3fdcd7
      Ian Abbott authored 
      The 'read' and 'write' file operations on comedi devices do not use the
main mutex in the `struct comedi_device` to avoid contention with ioctls
that may take a while to complete.  However, it is necessary to protect
against the device being detached while the operation is in progress.
Add member `struct rw_semaphore attach_lock` to `struct comedi_device`
for this purpose and initialize it on creation.

The actual locking and unlocking will be implemented by subsequent
patches.  Tasks that are attaching or detaching comedi devices will
write-acquire the new semaphore whilst also holding the main mutex in
the `struct comedi_device`.  Tasks that wish to protect against the
comedi device being detached need to acquire either the main mutex, or
read-acquire the new semaphore, or both in that order.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2f3fdcd7
    • Ian Abbott's avatar
      staging: comedi: add a couple of #includes to comedidev.h · ab3cb2e3
      Ian Abbott authored 
      Two structures defined in "comedidev.h" have an element of type
`spinlock_t`, so add `#include <linux/spinlock_types.h>` to declare it.
One structure has an element of type `struct mutex` so add `#include
<linux/mutex.h>` to declare it.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ab3cb2e3
    • Ian Abbott's avatar
      staging: comedi: remove unused command callback support · c265be01
      Ian Abbott authored 
      The 'kcomedilib' module used to provide functions to allow asynchronous
comedi commands to be set up from another kernel module, but now
commands can only be set up by ioctls from user space via the core
comedi module.  Since support for commands initiated from kernel space
has been dropped, the `cb_func` and `cb_arg` members of `struct
comedi_async` are never set (although the `cb_mask` member is still used
to mask comedi events).  The `SRF_USER` bit of the comedi subdevice
runflags is no longer needed to distinguish commands from user and
kernel space since they only come from user space.

Don't bother setting or testing the `SRF_USER` flag, and get rid of it,
along with the `cb_func` and `cb_arg` members.
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c265be01
    • Dulshani Gunawardhana's avatar
      staging: lustre: Fix sparse warning for one-bit signed bitfield · 5fb0a2fa
      Dulshani Gunawardhana authored 
      Fix the following sparse warning:
drivers/staging/lustre/lustre/llite/llite_internal.h:461:49: error:dubious one-bit signed bitfield
Signed-off-by: default avatarDulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
Reviewed-by: default avatarPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      5fb0a2fa
  3. 11 Nov, 2013 16 commits
  5. 10 Nov, 2013 10 commits
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