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author | Ian Abbott <abbotti@mev.co.uk> | 2016-12-08 16:53:10 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-12-08 23:01:23 +0300 |
commit | 3e0f9b2ca8e4839335e4d64ec0a75f4fd5111c4b (patch) | |
tree | 888fe093d6b8eab537059b032c8779f69dd90ced /drivers | |
parent | 3c87f653af6f5a94d30786903fe79f5816ec08f3 (diff) | |
download | linux-3e0f9b2ca8e4839335e4d64ec0a75f4fd5111c4b.tar.xz |
staging: comedi: comedidev.h: Document usage of 'detach' handler
Document when the "detach" handler function pointed to by the `detach`
member of a `struct comedi_driver` is called by the comedi core, and how
the "attach" and "auto_attach" handlers can defer clean-up to it when
they return an error to the comedi core. This is already mentioned as
part of the documentation for `comedi_auto_config()`, but is useful to
document it for `struct comedi_driver` as well, since
`comedi_auto_config()` is not usually called directly by low-level
comedi drivers, and it is not called at all for "legacy" comedi devices
that are configured manually.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/staging/comedi/comedidev.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index dcb637665eb7..0c7c37a8ff33 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -426,6 +426,18 @@ enum comedi_cb { * handler will be called with the COMEDI device structure's board_ptr member * pointing to the matched pointer to a board name within the driver's private * array of static, read-only board type information. + * + * The @detach handler has two roles. If a COMEDI device was successfully + * configured by the @attach or @auto_attach handler, it is called when the + * device is being deconfigured (by the %COMEDI_DEVCONFIG ioctl, or due to + * unloading of the driver, or due to device removal). It is also called when + * the @attach or @auto_attach handler returns an error. Therefore, the + * @attach or @auto_attach handlers can defer clean-up on error until the + * @detach handler is called. If the @attach or @auto_attach handlers free + * any resources themselves, they must prevent the @detach handler from + * freeing the same resources. The @detach handler must not assume that all + * resources requested by the @attach or @auto_attach handler were + * successfully allocated. */ struct comedi_driver { /* private: */ |