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From: Peter Hurley <peter@hurleysoftware.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Jiri Slaby" <jslaby@suse.cz>,
	"Christian Riesch" <christian.riesch@omicron.at>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
	"Denis Du" <dudenis2000@yahoo.ca>,
	"Måns Rullgård" <mans@mansr.com>,
	"Peter Hurley" <peter@hurleysoftware.com>
Subject: [PATCH v3 3/6] n_tty: Simplify throttle threshold calculation
Date: Fri, 16 Jan 2015 15:05:36 -0500	[thread overview]
Message-ID: <1421438739-29672-4-git-send-email-peter@hurleysoftware.com> (raw)
In-Reply-To: <1421438739-29672-1-git-send-email-peter@hurleysoftware.com>

The adjustments performed by receive_room() are to ensure a line
termination can always be written to the read buffer. However,
these adjustments are irrelevant to the throttle threshold (because
the threshold < buffer limit).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/n_tty.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index d4b14c3..7efabc4 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -262,7 +262,7 @@ static void n_tty_check_throttle(struct tty_struct *tty)
 	while (1) {
 		int throttled;
 		tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
-		if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
+		if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
 			break;
 		throttled = tty_throttle_safe(tty);
 		if (!throttled)
-- 
2.2.2

  parent reply	other threads:[~2015-01-16 20:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-13  1:47 [PATCH v2] n_tty: Fix unordered accesses to lockless read buffer Peter Hurley
2015-01-16 15:55 ` Peter Hurley
2015-01-16 20:05 ` [PATCH v3 0/6] N_TTY input path fixes Peter Hurley
2015-01-16 20:05   ` [PATCH v3 1/6] n_tty: Eliminate receive_room() from consumer/exclusive paths Peter Hurley
2015-01-16 20:05   ` [PATCH v3 2/6] n_tty: Fix throttle for canon lines > 3967 chars Peter Hurley
2015-01-16 20:05   ` Peter Hurley [this message]
2015-01-16 20:05   ` [PATCH v3 4/6] n_tty: Fix unordered accesses to lockless read buffer Peter Hurley
2015-01-16 20:05   ` [PATCH v3 5/6] n_tty: Fix PARMRK over-throttling Peter Hurley
2015-01-16 20:05   ` [PATCH v3 6/6] n_tty: Fix read buffer overwrite when no newline Peter Hurley

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