USB_PIPE_DRAIN_REQS(9F)USB_PIPE_DRAIN_REQS(9F)NAMEusb_pipe_drain_reqs - Allow completion of pending pipe requests
SYNOPSIS
#include <sys/usb/usba.h>
int usb_pipe_drain_reqs(dev_info_t *dip, usb_pipe_handle_t pipe_handle,
uint_t timeout, usb_flags_t usb_flags,
void (*callback)(usb_pipe_handle_t pipe_handle,
usb_opaque_t callback_arg, int rval, usb_cb_flags_t flags),
usb_opaque_t callback_arg);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)
PARAMETERS
dip
Pointer to the device's dev_info structure.
pipe_handle
Handle of the pipe containing pending requests.
timeout
Maximum wait time for requests to drain. Must be a non-
negative value in seconds. Zero specifies no timeout.
flags
USB_FLAGS_SLEEP is the only flag recognized. Wait for
completion and do not call callback.
callback
Callback handler to notify of asynchronous completion.
callback_arg
Second argument passed to callback function.
DESCRIPTION
The usb_pipe_drain_reqs() function provides waits for pending requests
to complete and then provides synchronous or asynchronous notification
that all pending requests on a non-shared pipe indicated by pipe_handle
have completed. For a shared pipe (such as the default control pipe
used by multiple drivers each managing one interface of a device), this
function provides notification that all pending requests on that pipe
that are associated with a given dip are completed.
The usb_pipe_drain_reqs() function can be used to notify a close proce‐
dure when the default control pipe is clear during device closure,
thereby allowing the close procedure to continue safely. Normally, a
synchronous call to usb_pipe_close(9F) allows all requests in a pipe to
finish before returning. However, a client driver cannot close the
default control pipe.
If USB_FLAGS_SLEEP is set in flags, block until all pending requests
are completed. Otherwise, return immediately and call the callback han‐
dler when all pending requests are completed.
The callback parameter accepts the asynchronous callback handler, which
takes the following arguments:
usb_pipe_handle_t default_pipe_handle
Handle of the pipe to drain.
usb_opaque_t callback_arg
callback_arg specified to usb_pipe_drain_reqs().
int rval
Request status.
usb_cb_flags_t callback_flags
Status of the queueing operation. Can be:
USB_CB_NO_INFO
Callback was uneventful.
USB_CB_ASYNC_REQ_FAILED
Error starting asynchronous request.
RETURN VALUES
USB_SUCCESS
Request is successful.
USB_INVALID_ARGS
dip argument is NULL. USB_FLAGS_SLEEP is clear
and callback is NULL.
USB_INVALID_CONTEXT
Called from callback context with the
USB_FLAGS_SLEEP flag set.
USB_INVALID_PIPE
Pipe is not open, is closing or is closed.
CONTEXT
May be called from user or kernel context.
If the USB_CB_ASYNC_REQ_FAILED bit is clear in usb_cb_flags_t, the
callback, if supplied, can block because it is executing in kernel con‐
text. Otherwise the callback cannot block. Please see usb_call‐
back_flags(9S) for more information on callbacks.
EXAMPLES
mydev_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
...
...
mydev_state->pipe_state = CLOSED;
/* Wait for pending requests of a pipe to finish. Don't timeout. */
(void) usb_pipe_drain_reqs(
dip, pipe_handle, 0, USB_FLAGS_SLEEP, NULL, 0);
/*
* Dismantle streams and tear down this instance,
* now that all requests have been sent.
*/
qprocsoff(q);
...
...
ddi_remove_minor_node(dip, NULL);
...
...
}
NOTES
For pipes other than the default control pipe, it is recommended to
close the pipe using a synchronous usb_pipe_close(). usb_pipe_close()
with the USB_FLAGS_SLEEP flag allows any pending requests in that pipe
to complete before returning.
Do not call usb_pipe_drain_reqs() while additional requests are being
submitted by a different thread. This action can stall the calling
thread of usb_pipe_drain_reqs() unnecessarily.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬───────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼───────────────────┤
│Architecture │ PCI-based systems │
├────────────────────┼───────────────────┤
│Interface stability │ Committed │
└────────────────────┴───────────────────┘
SEE ALSOattributes(5), usb_pipe_close(9F), usb_pipe_reset(9F), usb_call‐
back_flags(9S)
Jan 5, 2004 USB_PIPE_DRAIN_REQS(9F)
