From: Tony Lindgren <tony@atomide.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andy Shevchenko <andriy.shevchenko@intel.com>,
Jiri Slaby <jirislaby@kernel.org>,
Johan Hovold <johan@kernel.org>,
Vignesh Raghavendra <vigneshr@ti.com>,
linux-serial@vger.kernel.org, linux-omap@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 1/6] n_tty: Start making use of -EAGAIN returned from process_output_block()
Date: Tue, 21 Sep 2021 13:33:41 +0300 [thread overview]
Message-ID: <20210921103346.64824-2-tony@atomide.com> (raw)
In-Reply-To: <20210921103346.64824-1-tony@atomide.com>
We check for -EAGAIN in n_tty_write() but never currently get it from
process_output_block(). Let's add -EAGAIN handling and break out with 0
bytes processed. Note that if we return -EAGAIN from n_tty_write(), it
will be treated as error by the caller rather than a retry.
Looking at the patch description for commit 9ef8927f45f2 ("n_tty: check
for negative and zero space return from tty_write_room") it looks like we
have not made use of -EGAIN from process_output_block() so far, so this
does not seem like it's currently needed as a fix.
We can use -EAGAIN for serial layer power management changes as we now
will make use of write_room() returning 0 for an idled serial port.
Signed-off-by: Tony Lindgren <tony@atomide.com>
---
drivers/tty/n_tty.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -549,6 +549,8 @@ static ssize_t process_output_block(struct tty_struct *tty,
space = tty_write_room(tty);
if (space <= 0) {
mutex_unlock(&ldata->output_lock);
+ if (!space)
+ space = -EAGAIN;
return space;
}
if (nr > space)
@@ -2287,8 +2289,10 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
while (nr > 0) {
ssize_t num = process_output_block(tty, b, nr);
if (num < 0) {
- if (num == -EAGAIN)
- break;
+ if (num == -EAGAIN) {
+ retval = 0;
+ goto break_out;
+ }
retval = num;
goto break_out;
}
--
2.33.0
next prev parent reply other threads:[~2021-09-21 10:33 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-21 10:33 [PATCH 0/6] Get rid of pm_runtime_irq_safe() for 8250_omap Tony Lindgren
2021-09-21 10:33 ` Tony Lindgren [this message]
2021-09-21 11:58 ` [PATCH 1/6] n_tty: Start making use of -EAGAIN returned from process_output_block() Andy Shevchenko
2021-09-21 10:33 ` [PATCH 2/6] tty: n_gsm: Don't ignore write return value in gsmld_output() Tony Lindgren
2021-09-21 10:33 ` [PATCH 3/6] serial: core: Add new prep_tx for power management Tony Lindgren
2021-09-23 12:45 ` Johan Hovold
2021-09-23 15:02 ` Tony Lindgren
2021-09-24 14:37 ` Johan Hovold
2021-09-24 15:09 ` Tony Lindgren
2021-09-27 14:05 ` Johan Hovold
2021-09-21 10:33 ` [PATCH 4/6] serial: 8250: Implement " Tony Lindgren
2021-09-23 12:49 ` Johan Hovold
2021-09-23 15:05 ` Tony Lindgren
2021-09-24 14:44 ` Johan Hovold
2021-09-24 15:16 ` Tony Lindgren
2021-09-21 10:33 ` [PATCH 5/6] serial: 8250_omap: Require a valid wakeirq for deeper idle states Tony Lindgren
2021-09-21 10:33 ` [PATCH 6/6] serial: 8250_omap: Drop the use of pm_runtime_irq_safe() Tony Lindgren
2021-09-21 12:03 ` [PATCH 0/6] Get rid of pm_runtime_irq_safe() for 8250_omap Andy Shevchenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210921103346.64824-2-tony@atomide.com \
--to=tony@atomide.com \
--cc=andriy.shevchenko@intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=jirislaby@kernel.org \
--cc=johan@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=vigneshr@ti.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).