From 6e94dbc7a4e49a028b81302d755bba1a518f973b Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Wed, 5 May 2021 11:19:05 +0200 Subject: 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 Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Jonathan Corbet Cc: Arnd Bergmann Cc: Ulf Hansson Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: Shawn Guo Cc: Sascha Hauer Cc: Vineet Gupta Cc: "Maciej W. Rozycki" Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman --- drivers/tty/amiserial.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/tty/amiserial.c') 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; -- cgit v1.2.3