diff options
| author | Jiri Slaby <jslaby@suse.cz> | 2021-05-05 11:19:05 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-13 16:57:16 +0200 |
| commit | 6e94dbc7a4e49a028b81302d755bba1a518f973b (patch) | |
| tree | f96593e04f90e65cdca2110661b239cface50743 /drivers/tty/amiserial.c | |
| parent | tty: make fp of tty_ldisc_ops::receive_buf{,2} const (diff) | |
| download | linux-6e94dbc7a4e49a028b81302d755bba1a518f973b.tar.xz linux-6e94dbc7a4e49a028b81302d755bba1a518f973b.zip | |
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/amiserial.c')
| -rw-r--r-- | drivers/tty/amiserial.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c index ca48ce5a0862..a4b8876091d2 100644 --- a/drivers/tty/amiserial.c +++ b/drivers/tty/amiserial.c @@ -148,7 +148,7 @@ static __inline__ void rtsdtr_ctrl(int bits) * ------------------------------------------------------------ * rs_stop() and rs_start() * - * This routines are called before setting or resetting tty->stopped. + * This routines are called before setting or resetting tty->flow.stopped. * They enable or disable transmitter interrupts, as necessary. * ------------------------------------------------------------ */ @@ -309,7 +309,7 @@ static void transmit_chars(struct serial_state *info) return; } if (info->xmit.head == info->xmit.tail - || info->tport.tty->stopped + || info->tport.tty->flow.stopped || info->tport.tty->hw_stopped) { info->IER &= ~UART_IER_THRI; custom.intena = IF_TBE; @@ -768,7 +768,7 @@ static void rs_flush_chars(struct tty_struct *tty) unsigned long flags; if (info->xmit.head == info->xmit.tail - || tty->stopped + || tty->flow.stopped || tty->hw_stopped || !info->xmit.buf) return; @@ -812,7 +812,7 @@ static int rs_write(struct tty_struct * tty, const unsigned char *buf, int count local_irq_restore(flags); if (info->xmit.head != info->xmit.tail - && !tty->stopped + && !tty->flow.stopped && !tty->hw_stopped && !(info->IER & UART_IER_THRI)) { info->IER |= UART_IER_THRI; |