From 0f02321e4bd1b17eb957e077e868ef1611f5dbbd Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Thu, 25 Apr 2019 18:05:40 +0200 Subject: [PATCH] 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 Acked-by: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 33 ++++++++------------------------- drivers/usb/class/cdc-acm.h | 3 +-- 2 files changed, 9 insertions(+), 27 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index c03aa8550980..183b41753c98 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -468,7 +468,6 @@ static void acm_read_bulk_callback(struct urb *urb) { struct acm_rb *rb = urb->context; struct acm *acm = rb->instance; - unsigned long flags; int status = urb->status; bool stopped = false; bool stalled = false; @@ -525,15 +524,10 @@ static void acm_read_bulk_callback(struct urb *urb) return; } - /* throttle device if requested by tty */ - spin_lock_irqsave(&acm->read_lock, flags); - acm->throttled = acm->throttle_req; - if (!acm->throttled) { - spin_unlock_irqrestore(&acm->read_lock, flags); - acm_submit_read_urb(acm, rb->index, GFP_ATOMIC); - } else { - spin_unlock_irqrestore(&acm->read_lock, flags); - } + if (test_bit(ACM_THROTTLED, &acm->flags)) + return; + + acm_submit_read_urb(acm, rb->index, GFP_ATOMIC); } /* data interface wrote those outgoing bytes */ @@ -670,10 +664,7 @@ static int acm_port_activate(struct tty_port *port, struct tty_struct *tty) /* * Unthrottle device in case the TTY was closed while throttled. */ - spin_lock_irq(&acm->read_lock); - acm->throttled = 0; - acm->throttle_req = 0; - spin_unlock_irq(&acm->read_lock); + clear_bit(ACM_THROTTLED, &acm->flags); retval = acm_submit_read_urbs(acm, GFP_KERNEL); if (retval) @@ -841,27 +832,19 @@ static void acm_tty_throttle(struct tty_struct *tty) { struct acm *acm = tty->driver_data; - spin_lock_irq(&acm->read_lock); - acm->throttle_req = 1; - spin_unlock_irq(&acm->read_lock); + set_bit(ACM_THROTTLED, &acm->flags); } static void acm_tty_unthrottle(struct tty_struct *tty) { struct acm *acm = tty->driver_data; - unsigned int was_throttled; - spin_lock_irq(&acm->read_lock); - was_throttled = acm->throttled; - acm->throttled = 0; - acm->throttle_req = 0; - spin_unlock_irq(&acm->read_lock); + clear_bit(ACM_THROTTLED, &acm->flags); /* Matches the smp_mb__after_atomic() in acm_read_bulk_callback(). */ smp_mb(); - if (was_throttled) - acm_submit_read_urbs(acm, GFP_KERNEL); + acm_submit_read_urbs(acm, GFP_KERNEL); } static int acm_tty_break_ctl(struct tty_struct *tty, int state) diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h index 515aad0847ee..ca1c026382c2 100644 --- a/drivers/usb/class/cdc-acm.h +++ b/drivers/usb/class/cdc-acm.h @@ -108,6 +108,7 @@ struct acm { unsigned long flags; # define EVENT_TTY_WAKEUP 0 # define EVENT_RX_STALL 1 +# define ACM_THROTTLED 2 struct usb_cdc_line_coding line; /* bits, stop, parity */ struct work_struct work; /* work queue entry for line discipline waking up */ unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */ @@ -122,8 +123,6 @@ struct acm { unsigned int ctrl_caps; /* control capabilities from the class specific header */ unsigned int susp_count; /* number of suspended interfaces */ unsigned int combined_interfaces:1; /* control and data collapsed */ - unsigned int throttled:1; /* actually throttled */ - unsigned int throttle_req:1; /* throttle requested */ u8 bInterval; struct usb_anchor delayed; /* writes queued for a device about to be woken */ unsigned long quirks; -- 2.30.2