| Message ID | 20200130100658.683-1-johan@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 32553441569482e36e65371edb84494bcec53c03 |
| Headers | show |
| Series | USB: serial: relax unthrottle memory barrier | expand |
On Thu, Jan 30, 2020 at 11:06:58AM +0100, Johan Hovold wrote: > Commit a8d78d9f3856 ("USB: serial: clean up throttle handling") > converted the throttle handling to use atomic bitops. This means that we > can relax the smp_mb() in unthrottle() to smp_mb__after_atomic(), which > for example is a no-op on architectures like x86 that provide fully > ordered atomics. > > Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On Thu, 30 Jan 2020, Johan Hovold wrote: >Commit a8d78d9f3856 ("USB: serial: clean up throttle handling") >converted the throttle handling to use atomic bitops. This means that we >can relax the smp_mb() in unthrottle() to smp_mb__after_atomic(), which >for example is a no-op on architectures like x86 that provide fully >ordered atomics. > >Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
On Thu, Jan 30, 2020 at 07:33:28AM -0800, Davidlohr Bueso wrote: > On Thu, 30 Jan 2020, Johan Hovold wrote: > > >Commit a8d78d9f3856 ("USB: serial: clean up throttle handling") > >converted the throttle handling to use atomic bitops. This means that we > >can relax the smp_mb() in unthrottle() to smp_mb__after_atomic(), which > >for example is a no-op on architectures like x86 that provide fully > >ordered atomics. > > > >Signed-off-by: Johan Hovold <johan@kernel.org> > > Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Thanks for the review. Now applied. Johan
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index 1be8bea372a2..546a1c2ce2f2 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -417,7 +417,7 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb) /* * Make sure URB is marked as free before checking the throttled flag * to avoid racing with unthrottle() on another CPU. Matches the - * smp_mb() in unthrottle(). + * smp_mb__after_atomic() in unthrottle(). */ smp_mb__after_atomic(); @@ -489,7 +489,7 @@ void usb_serial_generic_unthrottle(struct tty_struct *tty) * Matches the smp_mb__after_atomic() in * usb_serial_generic_read_bulk_callback(). */ - smp_mb(); + smp_mb__after_atomic(); usb_serial_generic_submit_read_urbs(port, GFP_KERNEL); }
Commit a8d78d9f3856 ("USB: serial: clean up throttle handling") converted the throttle handling to use atomic bitops. This means that we can relax the smp_mb() in unthrottle() to smp_mb__after_atomic(), which for example is a no-op on architectures like x86 that provide fully ordered atomics. Signed-off-by: Johan Hovold <johan@kernel.org> --- drivers/usb/serial/generic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)