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n_tty: Remove reader wakeups for TTY_BREAK/TTY_PARITY chars

PATCH New Peter Hurley 1 participant 1 message Oct 14, 2015 TTY layer and serial drivers

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PATCH 1/1 n_tty: Remove reader wakeups for TTY_BREAK/TTY_PARITY chars

Waking the reader immediately upon receipt of TTY_BREAK or TTY_PARITY chars has no effect on the outcome of read():
1. Only non-canonical/EXTPROC mode applies since canonical mode will not return data until a line termination is received anyway
2. EXTPROC mode - the reader will always be woken by the input worker
3. Non-canonical modes
a. MIN == 0, TIME == 0
b. MIN == 0, TIME > 0
c. MIN > 0, TIME > 0
minimum_to_wake is always 1 in these modes so the reader will always be woken by the input worker
d. MIN > 0, TIME == 0
although the reader will not be woken by the input worker unless the minimum data is received, the reader would not otherwise have returned the received data

---
 drivers/tty/n_tty.c | 4 ----
 1 file changed, 4 deletions(-)
drivers/tty/n_tty.c +0 -4
index bd383c4..53ba0d6 100644
@@ -1180,8 +1180,6 @@ static void n_tty_receive_break(struct tty_struct *tty)
 		put_tty_queue('\0', ldata);
 	}
 	put_tty_queue('\0', ldata);
-	if (waitqueue_active(&tty->read_wait))
-		wake_up_interruptible_poll(&tty->read_wait, POLLIN);
 }
 
 /**
@@ -1238,8 +1236,6 @@ static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
 			put_tty_queue('\0', ldata);
 	} else
 		put_tty_queue(c, ldata);
-	if (waitqueue_active(&tty->read_wait))
-		wake_up_interruptible_poll(&tty->read_wait, POLLIN);
 }
 
 static void
Signature · 1 line
2.6.1