USB: f_fs: Fail stale read IOs after disconnect

After a USB disconnect, endpoints for adb are disabled.
After this no IO is allowed on the endpoints.
Since, adbd is not aware of this disconnect, it may
still perform read/writes IO. For adb writes, IOs are
failed, but for adb reads kernel waits untill endpoints
are enabled.

When a USB disconnect and adb read still queued
a buffer to kernel, ffs_epfile_io simply waits for
endpoint to be enabled. A next connect happens
and endpoints are enabled after set_alt, the adb
read stale buffer from previous session continues
and queues to endpoint.

All this time, adb did not close the epfile because
it did not get return status on the IOs which it
queued. This is an issue, because a new session
is not established and both userspace and kernel
goes out of sync.

To fix this issue, when endpoints are disbled
set epfile error. This epfile error is only cleared
in epfile open. This will ensure that after a USB
disconnect and connect, new session is established.

Also, return ENODEV if endpoints not enabled rather
than EINTR as EINTR case, and simply retries the
request. Incase usb_ep_queue failed, return -EIO
inspite of depend on return status from usb_ep_queue.

Change-Id: I6e677e98ec28e5462b372ed290acdde251286f48
Signed-off-by: Sujeet Kumar <ksujeet@codeaurora.org>
Signed-off-by: Mayank Rana <mrana@codeaurora.org>

0 files changed, 0 insertions, 0 deletions