USB: cdc-acm: clean up throttle handling
Clean up the throttle implementation by dropping the redundant throttle_req flag which was a remnant from back when USB serial had only a single read URB, something which was later carried over to cdc-acm. Also convert the throttled flag to an atomic bit flag. Signed-off-by: Johan Hovold <johan@kernel.org> Acked-by: Oliver Neukum <oneukum@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -468,7 +468,6 @@ static void acm_read_bulk_callback(struct urb *urb)
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{
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struct acm_rb *rb = urb->context;
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struct acm *acm = rb->instance;
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unsigned long flags;
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int status = urb->status;
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bool stopped = false;
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bool stalled = false;
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@ -525,15 +524,10 @@ static void acm_read_bulk_callback(struct urb *urb)
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return;
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}
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/* throttle device if requested by tty */
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spin_lock_irqsave(&acm->read_lock, flags);
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acm->throttled = acm->throttle_req;
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if (!acm->throttled) {
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spin_unlock_irqrestore(&acm->read_lock, flags);
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acm_submit_read_urb(acm, rb->index, GFP_ATOMIC);
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} else {
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spin_unlock_irqrestore(&acm->read_lock, flags);
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}
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if (test_bit(ACM_THROTTLED, &acm->flags))
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return;
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acm_submit_read_urb(acm, rb->index, GFP_ATOMIC);
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}
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/* data interface wrote those outgoing bytes */
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@ -670,10 +664,7 @@ static int acm_port_activate(struct tty_port *port, struct tty_struct *tty)
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/*
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* Unthrottle device in case the TTY was closed while throttled.
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*/
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spin_lock_irq(&acm->read_lock);
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acm->throttled = 0;
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acm->throttle_req = 0;
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spin_unlock_irq(&acm->read_lock);
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clear_bit(ACM_THROTTLED, &acm->flags);
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retval = acm_submit_read_urbs(acm, GFP_KERNEL);
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if (retval)
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@ -841,27 +832,19 @@ static void acm_tty_throttle(struct tty_struct *tty)
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{
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struct acm *acm = tty->driver_data;
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spin_lock_irq(&acm->read_lock);
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acm->throttle_req = 1;
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spin_unlock_irq(&acm->read_lock);
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set_bit(ACM_THROTTLED, &acm->flags);
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}
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static void acm_tty_unthrottle(struct tty_struct *tty)
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{
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struct acm *acm = tty->driver_data;
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unsigned int was_throttled;
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spin_lock_irq(&acm->read_lock);
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was_throttled = acm->throttled;
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acm->throttled = 0;
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acm->throttle_req = 0;
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spin_unlock_irq(&acm->read_lock);
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clear_bit(ACM_THROTTLED, &acm->flags);
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/* Matches the smp_mb__after_atomic() in acm_read_bulk_callback(). */
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smp_mb();
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if (was_throttled)
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acm_submit_read_urbs(acm, GFP_KERNEL);
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acm_submit_read_urbs(acm, GFP_KERNEL);
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}
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static int acm_tty_break_ctl(struct tty_struct *tty, int state)
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@ -108,6 +108,7 @@ struct acm {
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unsigned long flags;
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# define EVENT_TTY_WAKEUP 0
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# define EVENT_RX_STALL 1
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# define ACM_THROTTLED 2
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struct usb_cdc_line_coding line; /* bits, stop, parity */
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struct work_struct work; /* work queue entry for line discipline waking up */
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unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */
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@ -122,8 +123,6 @@ struct acm {
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unsigned int ctrl_caps; /* control capabilities from the class specific header */
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unsigned int susp_count; /* number of suspended interfaces */
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unsigned int combined_interfaces:1; /* control and data collapsed */
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unsigned int throttled:1; /* actually throttled */
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unsigned int throttle_req:1; /* throttle requested */
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u8 bInterval;
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struct usb_anchor delayed; /* writes queued for a device about to be woken */
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unsigned long quirks;
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