On Thu, Dec 18 2014, Robert Baldyga wrote:
> Since we can compose gadgets from many functions, there is the problem
> related to gadget breakage while FunctionFS daemon being closed. FFS
> function is userspace code so there is no way to know when it will close
> files (it doesn't matter what is the reason of this situation, it can
> be daemon logic, program breakage, process kill or any other). So when
> we have another function in gadget which, for example, sends some amount
> of data, does some software update or implements some real-time functionality,
> we may want to keep the gadget connected despite FFS function is no longer
> functional.
>
> We can't just remove one of functions from gadget since it has been
> enumerated, so the only way to keep entire gadget working is to make
> broken FFS function deactivated but still visible to host. For this
> purpose this patch introduces "no_disconnect" mode. It can be enabled
> by setting mount option "no_disconnect=1", and results with defering
> function disconnect to the moment of reopen ep0 file or filesystem
> unmount. After closing all endpoint files, FunctionFS is set to state
> FFS_DEACTIVATED.
>
> When ffs->state == FFS_DEACTIVATED:
> - function is still bound and visible to host,
> - setup requests are automatically stalled,
> - transfers on other endpoints are refused,
> - epfiles, except ep0, are deleted from the filesystem,
> - opening ep0 causes the function to be closed, and then FunctionFS
> is ready for descriptors and string write,
> - altsetting change causes the function to be closed - we want to keep
> function alive until another functions are potentialy used, altsetting
> change means that another configuration is being selected or USB cable
> was unplugged, which indicates that we don't need to stay longer in
> FFS_DEACTIVATED state
> - unmounting of the FunctionFS instance causes the function to be closed.
>
> Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
> @@ -1417,7 +1429,11 @@ static void ffs_data_opened(struct ffs_data *ffs)
> ENTER();
>
> atomic_inc(&ffs->ref);
> - atomic_inc(&ffs->opened);
> + if (atomic_add_return(1, &ffs->opened) == 1)
> + if (ffs->state == FFS_DEACTIVATED) {
> + ffs->state = FFS_CLOSING;
> + ffs_data_reset(ffs);
> + }
Wrong indention. Why not:
+ if (atomic_add_return(1, &ffs->opened) == 1 &&
+ ffs->state == FFS_DEACTIVATED) {
+ ffs->state = FFS_CLOSING;
+ ffs_data_reset(ffs);
+ }
> }
>
> static void ffs_data_put(struct ffs_data *ffs)
> @@ -1439,6 +1455,21 @@ static void ffs_data_closed(struct ffs_data *ffs)
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +--<mpn@xxxxxxxxxx>--<xmpp:mina86@xxxxxxxxxx>--ooO--(_)--Ooo--
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