Messages in this thread | | | From | Peter Hurley <> | Subject | [PATCH 0/2] fixes for empty tx buffer breakage | Date | Sun, 6 Jul 2014 11:29:51 -0400 |
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Cc: Seth Bollinger <sethb@digi.com> Cc: Aaro Koskinen <aaro.koskinen@iki.fi> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Greg,
I completed the audit of serial drivers after reports that several Sun serial drivers were broken by commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c, 'serial_core: Fix conditional start_tx on ring buffer not empty'.
I apologize for not submitting this sooner. The delay was due to an ongoing analysis of serial flow control prompted by Sam Ravnborg's question:
On 06/10/2014 03:24 PM, Sam Ravnborg wrote: > I also noticed the typical pattern is: > > if (uart_circ_empty(xmit) || uart_tx_stopped(port)) > > Should you use this pattern also in sunsab.c?
Unfortunately, that analysis revealed that tx flow control is largely SMP-unsafe, and it's fairly easy to corrupt the hardware state wrt. the tty flow control state.
I'm still working on the solutions to that; they're too extensive to submit for 3.16 anyway.
Regards,
Peter Hurley (2): serial: Test for no tx data on tx restart serial: arc_uart: Use uart_circ_empty() for open-coded comparison
drivers/tty/serial/arc_uart.c | 2 +- drivers/tty/serial/imx.c | 3 +++ drivers/tty/serial/ip22zilog.c | 2 ++ drivers/tty/serial/m32r_sio.c | 8 +++++--- drivers/tty/serial/pmac_zilog.c | 3 +++ drivers/tty/serial/sunsab.c | 3 +++ drivers/tty/serial/sunzilog.c | 2 ++ 7 files changed, 19 insertions(+), 4 deletions(-)
-- 2.0.0
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