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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 /drivers/tty/n_tty.c
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 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index c32318da5190..3566bb577eb0 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1289,7 +1289,7 @@ static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
}
}
- if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
+ if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) {
start_tty(tty);
process_echoes(tty);
}
@@ -1398,7 +1398,7 @@ static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
{
struct n_tty_data *ldata = tty->disc_data;
- if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
+ if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) {
start_tty(tty);
process_echoes(tty);
}
@@ -1427,7 +1427,7 @@ static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
if (c == STOP_CHAR(tty))
stop_tty(tty);
else if (c == START_CHAR(tty) ||
- (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
+ (tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) &&
c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
c != SUSP_CHAR(tty))) {
start_tty(tty);
@@ -1797,7 +1797,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
* Fix tty hang when I_IXON(tty) is cleared, but the tty
* been stopped by STOP_CHAR(tty) before it.
*/
- if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
+ if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow.tco_stopped) {
start_tty(tty);
process_echoes(tty);
}