From: Guenter Roeck <linux@roeck-us.net>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: heikki.krogerus@linux.intel.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org,
Badhri Jagan Sridharan <badhri@google.com>,
Kyle Tso <kyletso@google.com>,
Will McVicker <willmcvicker@google.com>
Subject: Re: [PATCH 1/5] USB: typec: tcpm: Prevent log overflow by removing old entries
Date: Thu, 10 Dec 2020 09:42:36 -0800 [thread overview]
Message-ID: <20201210174236.GB107395@roeck-us.net> (raw)
In-Reply-To: <20201210160521.3417426-2-gregkh@linuxfoundation.org>
On Thu, Dec 10, 2020 at 05:05:17PM +0100, Greg Kroah-Hartman wrote:
> From: Badhri Jagan Sridharan <badhri@google.com>
>
> TCPM logs overflow once the logbuffer is full. Clear old entries and
> allow logging the newer ones as the newer would be more relevant to the
> issue being debugged.
>
> Also, do not reset the logbuffer tail as end users might take back to
> back bugreports which would result in an empty buffer.
>
Historically, the reason for not doing this was that, once a problem occurs,
the log would fill up quickly (typically with reconnect attempts), and the
actual reason for the problem would be overwritten. Maybe that reasoning
no longer applies; I just wanted to point out that there _was_ a reason for
not clearing old log entries.
Guenter
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Cc: Kyle Tso <kyletso@google.com>
> Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
> Signed-off-by: Will McVicker <willmcvicker@google.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> drivers/usb/typec/tcpm/tcpm.c | 16 +++-------------
> 1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index cedc6cf82d61..0ceeab50ed64 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -470,12 +470,6 @@ static bool tcpm_port_is_disconnected(struct tcpm_port *port)
>
> #ifdef CONFIG_DEBUG_FS
>
> -static bool tcpm_log_full(struct tcpm_port *port)
> -{
> - return port->logbuffer_tail ==
> - (port->logbuffer_head + 1) % LOG_BUFFER_ENTRIES;
> -}
> -
> __printf(2, 0)
> static void _tcpm_log(struct tcpm_port *port, const char *fmt, va_list args)
> {
> @@ -495,11 +489,6 @@ static void _tcpm_log(struct tcpm_port *port, const char *fmt, va_list args)
>
> vsnprintf(tmpbuffer, sizeof(tmpbuffer), fmt, args);
>
> - if (tcpm_log_full(port)) {
> - port->logbuffer_head = max(port->logbuffer_head - 1, 0);
> - strcpy(tmpbuffer, "overflow");
> - }
> -
> if (port->logbuffer_head < 0 ||
> port->logbuffer_head >= LOG_BUFFER_ENTRIES) {
> dev_warn(port->dev,
> @@ -519,6 +508,9 @@ static void _tcpm_log(struct tcpm_port *port, const char *fmt, va_list args)
> (unsigned long)ts_nsec, rem_nsec / 1000,
> tmpbuffer);
> port->logbuffer_head = (port->logbuffer_head + 1) % LOG_BUFFER_ENTRIES;
> + if (port->logbuffer_head == port->logbuffer_tail)
> + port->logbuffer_tail =
> + (port->logbuffer_tail + 1) % LOG_BUFFER_ENTRIES;
>
> abort:
> mutex_unlock(&port->logbuffer_lock);
> @@ -622,8 +614,6 @@ static int tcpm_debug_show(struct seq_file *s, void *v)
> seq_printf(s, "%s\n", port->logbuffer[tail]);
> tail = (tail + 1) % LOG_BUFFER_ENTRIES;
> }
> - if (!seq_has_overflowed(s))
> - port->logbuffer_tail = tail;
> mutex_unlock(&port->logbuffer_lock);
>
> return 0;
> --
> 2.29.2
>
next prev parent reply other threads:[~2020-12-10 17:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-10 16:05 [PATCH 0/5] USB: typec: various patches Greg Kroah-Hartman
2020-12-10 16:05 ` [PATCH 1/5] USB: typec: tcpm: Prevent log overflow by removing old entries Greg Kroah-Hartman
2020-12-10 17:42 ` Guenter Roeck [this message]
2020-12-10 19:10 ` Badhri Jagan Sridharan
2020-12-11 0:01 ` Guenter Roeck
2020-12-10 16:05 ` [PATCH 2/5] USB: typec: tcpm: Hard Reset after not receiving a Request Greg Kroah-Hartman
2020-12-10 17:43 ` Guenter Roeck
2020-12-10 16:05 ` [PATCH 3/5] USB: typec: tcpm: Fix PR_SWAP error handling Greg Kroah-Hartman
2020-12-10 17:43 ` Guenter Roeck
2020-12-10 16:05 ` [PATCH 4/5] USB: typec: tcpm: Add a 30ms room for tPSSourceOn in PR_SWAP Greg Kroah-Hartman
2020-12-10 17:44 ` Guenter Roeck
2020-12-10 16:05 ` [PATCH 5/5] USB: typec: tcpci: Add Bleed discharge to POWER_CONTROL definition Greg Kroah-Hartman
2020-12-10 17:45 ` Guenter Roeck
2020-12-10 18:56 ` Badhri Jagan Sridharan
2020-12-11 4:47 ` Badhri Jagan Sridharan
2020-12-11 6:38 ` Greg Kroah-Hartman
2020-12-11 8:30 ` [PATCH 0/5] USB: typec: various patches Heikki Krogerus
2020-12-11 9:51 ` Greg Kroah-Hartman
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=20201210174236.GB107395@roeck-us.net \
--to=linux@roeck-us.net \
--cc=badhri@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=heikki.krogerus@linux.intel.com \
--cc=kyletso@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=willmcvicker@google.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).