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Message-ID: <20230919085156.1578-5-jirislaby@kernel.org>
Date: Tue, 19 Sep 2023 10:51:45 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 04/15] tty: n_tty: invert the condition in copy_from_read_buf()
Make "no numbers available" a fast quit from the function. And do the
heavy work outside the 'if'. This makes the code more understandable and
conforming to the common kernel coding style.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
drivers/tty/n_tty.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 6a112910c058..922fb61b587a 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1966,24 +1966,26 @@ static bool copy_from_read_buf(const struct tty_struct *tty, u8 **kbp,
size_t tail = MASK(ldata->read_tail);
n = min3(head - ldata->read_tail, N_TTY_BUF_SIZE - tail, *nr);
- if (n) {
- u8 *from = read_buf_addr(ldata, tail);
- memcpy(*kbp, from, n);
- is_eof = n == 1 && *from == EOF_CHAR(tty);
- tty_audit_add_data(tty, from, n);
- zero_buffer(tty, from, n);
- smp_store_release(&ldata->read_tail, ldata->read_tail + n);
- /* Turn single EOF into zero-length read */
- if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
- (head == ldata->read_tail))
- return false;
- *kbp += n;
- *nr -= n;
-
- /* If we have more to copy, let the caller know */
- return head != ldata->read_tail;
- }
- return false;
+ if (!n)
+ return false;
+
+ u8 *from = read_buf_addr(ldata, tail);
+ memcpy(*kbp, from, n);
+ is_eof = n == 1 && *from == EOF_CHAR(tty);
+ tty_audit_add_data(tty, from, n);
+ zero_buffer(tty, from, n);
+ smp_store_release(&ldata->read_tail, ldata->read_tail + n);
+
+ /* Turn single EOF into zero-length read */
+ if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
+ head == ldata->read_tail)
+ return false;
+
+ *kbp += n;
+ *nr -= n;
+
+ /* If we have more to copy, let the caller know */
+ return head != ldata->read_tail;
}
/**
--
2.42.0
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