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author | Ian Abbott <abbotti@mev.co.uk> | 2013-04-04 13:58:56 (GMT) |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-05 21:33:18 (GMT) |
commit | b2a644b435de1d45bd8b5d4e391c894a662eb1f3 (patch) | |
tree | 1ef1cdb7384a52025bc8c9ed2c643c493b7ad582 /drivers/staging/comedi/comedi_fops.c | |
parent | d9740a0314a744a8f6406c55e033d60c45b67f74 (diff) | |
download | linux-fsl-qoriq-b2a644b435de1d45bd8b5d4e391c894a662eb1f3.tar.xz |
staging: comedi: simplify driver module counting
For a legacy device attachment with the `COMEDI_DEVCONFIG` ioctl,
`do_devconfig_ioctl()` calls `comedi_device_attach()` to find a matching
device driver and attach the device. It then tries to increment the
device driver's module count and if that fails it detaches the device.
So on successful attachment of a device by the `COMEDI_DEVCONFIG` ioctl,
the device driver's module count will have been incremented.
`comedi_device_attach()` is called from nowhere else. It already
increments the device driver's module count temporarily and decrements
it again; if it gets as far as calling `comedi_device_postconfig()` the
module count is decremented within that function.
Simplify the above by removing the decrement of the device driver module
count from `comedi_device_postconfig()`. If the call to
`comedi_device_postconfig()` succeeds, `comedi_device_attach()` will
return with the module count still incremented, otherwise decrement the
module count before returning the error. Don't try and increment the
module count in `do_devconfig_ioctl()` after a successful return from
`comedi_device_attach()` as the module count has now already been
incremented.
`comedi_device_postconfig()` is also called by `comedi_auto_config()`
which currently has to increment the device driver's module count
temporarily so that `comedi_device_postconfig()` can decrement it, but
always returns with no overall change to the module count. Remove all
the module count manipulations from `comedi_device_postconfig()`. There
is no other reason for `comedi_auto_config()` to increment the device
driver's module count temporarily, since it is only called (indirectly)
from the device driver itself (usually via one of the wrappers
`comedi_pci_auto_config()` or `comedi_usb_auto_config()`).
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/comedi_fops.c')
-rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 12 |
1 files changed, 2 insertions, 10 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 1c310e7..229be41 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -520,7 +520,6 @@ static int do_devconfig_ioctl(struct comedi_device *dev, struct comedi_devconfig __user *arg) { struct comedi_devconfig it; - int ret; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -551,15 +550,8 @@ static int do_devconfig_ioctl(struct comedi_device *dev, /* don't re-use dynamically allocated comedi devices */ return -EBUSY; - ret = comedi_device_attach(dev, &it); - if (ret == 0) { - if (!try_module_get(dev->driver->module)) { - comedi_device_detach(dev); - ret = -ENOSYS; - } - } - - return ret; + /* This increments the driver module count on success. */ + return comedi_device_attach(dev, &it); } /* |