summaryrefslogtreecommitdiff
path: root/include/linux/serial_core.h
diff options
context:
space:
mode:
authorJiri Slaby <jslaby@suse.cz>2021-05-05 12:19:05 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-05-13 17:57:16 +0300
commit6e94dbc7a4e49a028b81302d755bba1a518f973b (patch)
treef96593e04f90e65cdca2110661b239cface50743 /include/linux/serial_core.h
parent0f3dcf3b5d76669123bf99fec812b8b0acd60375 (diff)
downloadlinux-6e94dbc7a4e49a028b81302d755bba1a518f973b.tar.xz
tty: cumulate and document tty_struct::flow* members
Group the flow flags under a single struct called flow. The new struct contains 'stopped' and 'tco_stopped' bools which used to be bits in a bitfield. The struct also contains the lock protecting them to potentially share the same cache line. Note that commit c545b66c6922b (tty: Serialize tcflow() with other tty flow control changes) added a padding to the original bitfield. It was for the bitfield to occupy a whole 64b word to avoid interferring stores on Alpha (cannot we evaporate this arch with weird implications to C code yet?). But it doesn't work as expected as the padding (tty_struct::unused) is aligned to a 8B boundary too and occupies some bytes from the next word. So make it reliable by: 1) setting __aligned of the struct -- that aligns the start, and 2) making 'unsigned long unused[0]' as the last member of the struct -- pads the end. This is also the perfect time to start the documentation of tty_struct where all this lives. So we start by documenting what these bools actually serve for. And why we do all the alignment dances. Only the few up-to-date information from the Theodore's comment made it into this new Kerneldoc comment. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Shawn Guo <shawnguo@kernel.org> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: "Maciej W. Rozycki" <macro@orcam.me.uk> Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/serial_core.h')
-rw-r--r--include/linux/serial_core.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index d7ed00f1594e..7445c8fd88c0 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -428,7 +428,7 @@ int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
static inline int uart_tx_stopped(struct uart_port *port)
{
struct tty_struct *tty = port->state->port.tty;
- if ((tty && tty->stopped) || port->hw_stopped)
+ if ((tty && tty->flow.stopped) || port->hw_stopped)
return 1;
return 0;
}