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[PATCH v2 0/3] n_tty_read() helper cleanups

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  [PATCH v2 0/3] n_tty_read() helper cleanups Peter Hurley <peter@hurleysoftware.com> - 2015-11-27 20:20 +0100
    [PATCH v2 3/3] n_tty: Reduce branching in canon_copy_from_read_buf() Peter Hurley <peter@hurleysoftware.com> - 2015-11-27 20:20 +0100

#1278928 — [PATCH v2 0/3] n_tty_read() helper cleanups

Hi Greg,

This series rebases a couple of already-sent patches on top of the
EOF push bug fix, "n_tty: Fix poll() after buffer-limited eof push read",
and adds a third to reduce branching (which hopefully clarifies the
copy algorithm some).

I will also resend the "Rework tty audit" series, which requires this
series.

Regards,

Peter Hurley (3):
  n_tty: Uninline tty_copy_to_user()
  n_tty: Clarify copy_from_read_buf()
  n_tty: Reduce branching in canon_copy_from_read_buf()

 drivers/tty/n_tty.c | 48 +++++++++++++++++++++++++-----------------------
 1 file changed, 25 insertions(+), 23 deletions(-)

-- 
2.6.3

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#1278930 — [PATCH v2 3/3] n_tty: Reduce branching in canon_copy_from_read_buf()

Instead of compare-and-set, just compute 'found'.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/n_tty.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index eab606a..9b0b610 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2079,10 +2079,9 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	if (eol == N_TTY_BUF_SIZE && more) {
 		/* scan wrapped without finding set bit */
 		eol = find_next_bit(ldata->read_flags, more, 0);
-		if (eol != more)
-			found = 1;
-	} else if (eol != size)
-		found = 1;
+		found = eol != more;
+	} else
+		found = eol != size;
 
 	n = eol - tail;
 	if (n > N_TTY_BUF_SIZE)
-- 
2.6.3

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