* [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands
@ 2020-08-27 20:41 Raul E Rangel
2020-08-27 20:41 ` [PATCH v2 2/2] Input: i8042 - Lock i8042_mutex before flushing Raul E Rangel
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Raul E Rangel @ 2020-08-27 20:41 UTC (permalink / raw)
To: linux-input
Cc: dmitry.torokhov, Shirish.S, Raul E Rangel, Andy Shevchenko,
Dan Murphy, Darren Hart, Jacek Anaszewski, Lee, Chun-Yi,
Pavel Machek, Rajat Jain, Stephen Boyd, linux-kernel, linux-leds,
platform-driver-x86
The i8042_mutex must be held by writers of the AUX and KBD ports, as
well as users of i8042_command. There were a lot of users of
i8042_command that were not calling i8042_lock_chip/i8042_unlock_chip.
This resulted in i8042_commands being issues in between PS/2
transactions.
This change moves the mutex lock into i8042_command and removes the
burden of locking the mutex from the callers.
It is expected that the i8042_mutex is locked before calling
i8042_aux_write or i8042_kbd_write. This is currently done by the PS/2
layer via ps2_begin_command and ps2_end_command. Other modules
(serio_raw) do not currently lock the mutex, so there is still a
possibility for intermixed commands.
Link: https://lore.kernel.org/linux-input/CAHQZ30ANTeM-pgdYZ4AbgxsnevBJnJgKZ1Kg+Uy8oSXZUvz=og@mail.gmail.com
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
---
Tested this on a device with only a PS/2 keyboard. I was able to do
1200+ suspend/resume cycles.
Also tested this on a device with a PS/2 keyboard and a PS/2 mouse.
I was able to do 250+ iterations with out problems.
Changes in v2:
- Fixed bad indent
- Added Link: tag
- Removed left over rc variable
drivers/input/serio/i8042.c | 29 ++++++++++++++---------------
drivers/leds/leds-clevo-mail.c | 9 ---------
drivers/platform/x86/acer-wmi.c | 2 --
drivers/platform/x86/amilo-rfkill.c | 6 +-----
include/linux/i8042.h | 10 ----------
5 files changed, 15 insertions(+), 41 deletions(-)
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 0dddf273afd94..65ca6b47f41e8 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -137,8 +137,7 @@ static DEFINE_SPINLOCK(i8042_lock);
/*
* Writers to AUX and KBD ports as well as users issuing i8042_command
- * directly should acquire i8042_mutex (by means of calling
- * i8042_lock_chip() and i8042_unlock_ship() helpers) to ensure that
+ * directly should acquire i8042_mutex to ensure that
* they do not disturb each other (unfortunately in many i8042
* implementations write to one of the ports will immediately abort
* command that is being processed by another port).
@@ -173,18 +172,6 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id);
static bool (*i8042_platform_filter)(unsigned char data, unsigned char str,
struct serio *serio);
-void i8042_lock_chip(void)
-{
- mutex_lock(&i8042_mutex);
-}
-EXPORT_SYMBOL(i8042_lock_chip);
-
-void i8042_unlock_chip(void)
-{
- mutex_unlock(&i8042_mutex);
-}
-EXPORT_SYMBOL(i8042_unlock_chip);
-
int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
struct serio *serio))
{
@@ -343,10 +330,14 @@ int i8042_command(unsigned char *param, int command)
unsigned long flags;
int retval;
+ mutex_lock(&i8042_mutex);
+
spin_lock_irqsave(&i8042_lock, flags);
retval = __i8042_command(param, command);
spin_unlock_irqrestore(&i8042_lock, flags);
+ mutex_unlock(&i8042_mutex);
+
return retval;
}
EXPORT_SYMBOL(i8042_command);
@@ -379,10 +370,18 @@ static int i8042_kbd_write(struct serio *port, unsigned char c)
static int i8042_aux_write(struct serio *serio, unsigned char c)
{
struct i8042_port *port = serio->port_data;
+ unsigned long flags;
+ int retval = 0;
+
+ spin_lock_irqsave(&i8042_lock, flags);
- return i8042_command(&c, port->mux == -1 ?
+ retval = __i8042_command(&c, port->mux == -1 ?
I8042_CMD_AUX_SEND :
I8042_CMD_MUX_SEND + port->mux);
+
+ spin_unlock_irqrestore(&i8042_lock, flags);
+
+ return retval;
}
diff --git a/drivers/leds/leds-clevo-mail.c b/drivers/leds/leds-clevo-mail.c
index f512e99b976b1..6c3d7e54f95cf 100644
--- a/drivers/leds/leds-clevo-mail.c
+++ b/drivers/leds/leds-clevo-mail.c
@@ -95,17 +95,12 @@ MODULE_DEVICE_TABLE(dmi, clevo_mail_led_dmi_table);
static void clevo_mail_led_set(struct led_classdev *led_cdev,
enum led_brightness value)
{
- i8042_lock_chip();
-
if (value == LED_OFF)
i8042_command(NULL, CLEVO_MAIL_LED_OFF);
else if (value <= LED_HALF)
i8042_command(NULL, CLEVO_MAIL_LED_BLINK_0_5HZ);
else
i8042_command(NULL, CLEVO_MAIL_LED_BLINK_1HZ);
-
- i8042_unlock_chip();
-
}
static int clevo_mail_led_blink(struct led_classdev *led_cdev,
@@ -114,8 +109,6 @@ static int clevo_mail_led_blink(struct led_classdev *led_cdev,
{
int status = -EINVAL;
- i8042_lock_chip();
-
if (*delay_on == 0 /* ms */ && *delay_off == 0 /* ms */) {
/* Special case: the leds subsystem requested us to
* chose one user friendly blinking of the LED, and
@@ -142,8 +135,6 @@ static int clevo_mail_led_blink(struct led_classdev *led_cdev,
*delay_on, *delay_off);
}
- i8042_unlock_chip();
-
return status;
}
diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index 60c18f21588dd..6cb6f800503b2 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -1044,9 +1044,7 @@ static acpi_status WMID_set_u32(u32 value, u32 cap)
return AE_BAD_PARAMETER;
if (quirks->mailled == 1) {
param = value ? 0x92 : 0x93;
- i8042_lock_chip();
i8042_command(¶m, 0x1059);
- i8042_unlock_chip();
return 0;
}
break;
diff --git a/drivers/platform/x86/amilo-rfkill.c b/drivers/platform/x86/amilo-rfkill.c
index 493e169c8f615..c981c6e07ff94 100644
--- a/drivers/platform/x86/amilo-rfkill.c
+++ b/drivers/platform/x86/amilo-rfkill.c
@@ -28,12 +28,8 @@
static int amilo_a1655_rfkill_set_block(void *data, bool blocked)
{
u8 param = blocked ? A1655_WIFI_OFF : A1655_WIFI_ON;
- int rc;
- i8042_lock_chip();
- rc = i8042_command(¶m, A1655_WIFI_COMMAND);
- i8042_unlock_chip();
- return rc;
+ return i8042_command(¶m, A1655_WIFI_COMMAND);
}
static const struct rfkill_ops amilo_a1655_rfkill_ops = {
diff --git a/include/linux/i8042.h b/include/linux/i8042.h
index 0261e2fb36364..1c081081c161d 100644
--- a/include/linux/i8042.h
+++ b/include/linux/i8042.h
@@ -55,8 +55,6 @@ struct serio;
#if defined(CONFIG_SERIO_I8042) || defined(CONFIG_SERIO_I8042_MODULE)
-void i8042_lock_chip(void);
-void i8042_unlock_chip(void);
int i8042_command(unsigned char *param, int command);
int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
struct serio *serio));
@@ -65,14 +63,6 @@ int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,
#else
-static inline void i8042_lock_chip(void)
-{
-}
-
-static inline void i8042_unlock_chip(void)
-{
-}
-
static inline int i8042_command(unsigned char *param, int command)
{
return -ENODEV;
--
2.28.0.297.g1956fa8f8d-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2 2/2] Input: i8042 - Lock i8042_mutex before flushing
2020-08-27 20:41 [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Raul E Rangel
@ 2020-08-27 20:41 ` Raul E Rangel
2020-10-28 20:35 ` [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Hans de Goede
2020-12-07 6:40 ` Dmitry Torokhov
2 siblings, 0 replies; 4+ messages in thread
From: Raul E Rangel @ 2020-08-27 20:41 UTC (permalink / raw)
To: linux-input
Cc: dmitry.torokhov, Shirish.S, Raul E Rangel, Rajat Jain,
Stephen Boyd, linux-kernel
Make i8042_flush lock the i8042_mutex before flushing the buffer. This
will prevent i8042_flush from clearing the buffer while a PS/2 command is
in progress. I'm not sure if this is really possible. We already
hold the lock when calling i8042_command, so this makes i8042_flush have
the same behavior.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
---
(no changes since v1)
drivers/input/serio/i8042.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 65ca6b47f41e8..b7ed93c5095c4 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -254,6 +254,8 @@ static int i8042_flush(void)
int count = 0;
int retval = 0;
+ mutex_lock(&i8042_mutex);
+
spin_lock_irqsave(&i8042_lock, flags);
while ((str = i8042_read_status()) & I8042_STR_OBF) {
@@ -270,6 +272,8 @@ static int i8042_flush(void)
spin_unlock_irqrestore(&i8042_lock, flags);
+ mutex_unlock(&i8042_mutex);
+
return retval;
}
--
2.28.0.297.g1956fa8f8d-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands
2020-08-27 20:41 [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Raul E Rangel
2020-08-27 20:41 ` [PATCH v2 2/2] Input: i8042 - Lock i8042_mutex before flushing Raul E Rangel
@ 2020-10-28 20:35 ` Hans de Goede
2020-12-07 6:40 ` Dmitry Torokhov
2 siblings, 0 replies; 4+ messages in thread
From: Hans de Goede @ 2020-10-28 20:35 UTC (permalink / raw)
To: Raul E Rangel, linux-input
Cc: dmitry.torokhov, Shirish.S, Andy Shevchenko, Dan Murphy,
Darren Hart, Jacek Anaszewski, Lee, Chun-Yi, Pavel Machek,
Rajat Jain, Stephen Boyd, linux-kernel, linux-leds,
platform-driver-x86
Hi,
Quick self intro: I have take over drivers/platform/x86
maintainership from Andy; and I'm working my way through
the backlog of old patches in patchwork:
https://patchwork.kernel.org/project/platform-driver-x86/list/
On 8/27/20 10:41 PM, Raul E Rangel wrote:
> The i8042_mutex must be held by writers of the AUX and KBD ports, as
> well as users of i8042_command. There were a lot of users of
> i8042_command that were not calling i8042_lock_chip/i8042_unlock_chip.
> This resulted in i8042_commands being issues in between PS/2
> transactions.
>
> This change moves the mutex lock into i8042_command and removes the
> burden of locking the mutex from the callers.
>
> It is expected that the i8042_mutex is locked before calling
> i8042_aux_write or i8042_kbd_write. This is currently done by the PS/2
> layer via ps2_begin_command and ps2_end_command. Other modules
> (serio_raw) do not currently lock the mutex, so there is still a
> possibility for intermixed commands.
>
> Link: https://lore.kernel.org/linux-input/CAHQZ30ANTeM-pgdYZ4AbgxsnevBJnJgKZ1Kg+Uy8oSXZUvz=og@mail.gmail.com
> Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Patch looks good to me, you can add my:
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
(for both the drivers/platform/x86 bits and in general).
Dmitry, feel free to merge this through the input tree, I don't
expect the touched pdx86 parts to see any changes this cycle.
Regards,
Hans
> ---
> Tested this on a device with only a PS/2 keyboard. I was able to do
> 1200+ suspend/resume cycles.
>
> Also tested this on a device with a PS/2 keyboard and a PS/2 mouse.
> I was able to do 250+ iterations with out problems.
>
> Changes in v2:
> - Fixed bad indent
> - Added Link: tag
> - Removed left over rc variable
>
> drivers/input/serio/i8042.c | 29 ++++++++++++++---------------
> drivers/leds/leds-clevo-mail.c | 9 ---------
> drivers/platform/x86/acer-wmi.c | 2 --
> drivers/platform/x86/amilo-rfkill.c | 6 +-----
> include/linux/i8042.h | 10 ----------
> 5 files changed, 15 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
> index 0dddf273afd94..65ca6b47f41e8 100644
> --- a/drivers/input/serio/i8042.c
> +++ b/drivers/input/serio/i8042.c
> @@ -137,8 +137,7 @@ static DEFINE_SPINLOCK(i8042_lock);
>
> /*
> * Writers to AUX and KBD ports as well as users issuing i8042_command
> - * directly should acquire i8042_mutex (by means of calling
> - * i8042_lock_chip() and i8042_unlock_ship() helpers) to ensure that
> + * directly should acquire i8042_mutex to ensure that
> * they do not disturb each other (unfortunately in many i8042
> * implementations write to one of the ports will immediately abort
> * command that is being processed by another port).
> @@ -173,18 +172,6 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id);
> static bool (*i8042_platform_filter)(unsigned char data, unsigned char str,
> struct serio *serio);
>
> -void i8042_lock_chip(void)
> -{
> - mutex_lock(&i8042_mutex);
> -}
> -EXPORT_SYMBOL(i8042_lock_chip);
> -
> -void i8042_unlock_chip(void)
> -{
> - mutex_unlock(&i8042_mutex);
> -}
> -EXPORT_SYMBOL(i8042_unlock_chip);
> -
> int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
> struct serio *serio))
> {
> @@ -343,10 +330,14 @@ int i8042_command(unsigned char *param, int command)
> unsigned long flags;
> int retval;
>
> + mutex_lock(&i8042_mutex);
> +
> spin_lock_irqsave(&i8042_lock, flags);
> retval = __i8042_command(param, command);
> spin_unlock_irqrestore(&i8042_lock, flags);
>
> + mutex_unlock(&i8042_mutex);
> +
> return retval;
> }
> EXPORT_SYMBOL(i8042_command);
> @@ -379,10 +370,18 @@ static int i8042_kbd_write(struct serio *port, unsigned char c)
> static int i8042_aux_write(struct serio *serio, unsigned char c)
> {
> struct i8042_port *port = serio->port_data;
> + unsigned long flags;
> + int retval = 0;
> +
> + spin_lock_irqsave(&i8042_lock, flags);
>
> - return i8042_command(&c, port->mux == -1 ?
> + retval = __i8042_command(&c, port->mux == -1 ?
> I8042_CMD_AUX_SEND :
> I8042_CMD_MUX_SEND + port->mux);
> +
> + spin_unlock_irqrestore(&i8042_lock, flags);
> +
> + return retval;
> }
>
>
> diff --git a/drivers/leds/leds-clevo-mail.c b/drivers/leds/leds-clevo-mail.c
> index f512e99b976b1..6c3d7e54f95cf 100644
> --- a/drivers/leds/leds-clevo-mail.c
> +++ b/drivers/leds/leds-clevo-mail.c
> @@ -95,17 +95,12 @@ MODULE_DEVICE_TABLE(dmi, clevo_mail_led_dmi_table);
> static void clevo_mail_led_set(struct led_classdev *led_cdev,
> enum led_brightness value)
> {
> - i8042_lock_chip();
> -
> if (value == LED_OFF)
> i8042_command(NULL, CLEVO_MAIL_LED_OFF);
> else if (value <= LED_HALF)
> i8042_command(NULL, CLEVO_MAIL_LED_BLINK_0_5HZ);
> else
> i8042_command(NULL, CLEVO_MAIL_LED_BLINK_1HZ);
> -
> - i8042_unlock_chip();
> -
> }
>
> static int clevo_mail_led_blink(struct led_classdev *led_cdev,
> @@ -114,8 +109,6 @@ static int clevo_mail_led_blink(struct led_classdev *led_cdev,
> {
> int status = -EINVAL;
>
> - i8042_lock_chip();
> -
> if (*delay_on == 0 /* ms */ && *delay_off == 0 /* ms */) {
> /* Special case: the leds subsystem requested us to
> * chose one user friendly blinking of the LED, and
> @@ -142,8 +135,6 @@ static int clevo_mail_led_blink(struct led_classdev *led_cdev,
> *delay_on, *delay_off);
> }
>
> - i8042_unlock_chip();
> -
> return status;
> }
>
> diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
> index 60c18f21588dd..6cb6f800503b2 100644
> --- a/drivers/platform/x86/acer-wmi.c
> +++ b/drivers/platform/x86/acer-wmi.c
> @@ -1044,9 +1044,7 @@ static acpi_status WMID_set_u32(u32 value, u32 cap)
> return AE_BAD_PARAMETER;
> if (quirks->mailled == 1) {
> param = value ? 0x92 : 0x93;
> - i8042_lock_chip();
> i8042_command(¶m, 0x1059);
> - i8042_unlock_chip();
> return 0;
> }
> break;
> diff --git a/drivers/platform/x86/amilo-rfkill.c b/drivers/platform/x86/amilo-rfkill.c
> index 493e169c8f615..c981c6e07ff94 100644
> --- a/drivers/platform/x86/amilo-rfkill.c
> +++ b/drivers/platform/x86/amilo-rfkill.c
> @@ -28,12 +28,8 @@
> static int amilo_a1655_rfkill_set_block(void *data, bool blocked)
> {
> u8 param = blocked ? A1655_WIFI_OFF : A1655_WIFI_ON;
> - int rc;
>
> - i8042_lock_chip();
> - rc = i8042_command(¶m, A1655_WIFI_COMMAND);
> - i8042_unlock_chip();
> - return rc;
> + return i8042_command(¶m, A1655_WIFI_COMMAND);
> }
>
> static const struct rfkill_ops amilo_a1655_rfkill_ops = {
> diff --git a/include/linux/i8042.h b/include/linux/i8042.h
> index 0261e2fb36364..1c081081c161d 100644
> --- a/include/linux/i8042.h
> +++ b/include/linux/i8042.h
> @@ -55,8 +55,6 @@ struct serio;
>
> #if defined(CONFIG_SERIO_I8042) || defined(CONFIG_SERIO_I8042_MODULE)
>
> -void i8042_lock_chip(void);
> -void i8042_unlock_chip(void);
> int i8042_command(unsigned char *param, int command);
> int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
> struct serio *serio));
> @@ -65,14 +63,6 @@ int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,
>
> #else
>
> -static inline void i8042_lock_chip(void)
> -{
> -}
> -
> -static inline void i8042_unlock_chip(void)
> -{
> -}
> -
> static inline int i8042_command(unsigned char *param, int command)
> {
> return -ENODEV;
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands
2020-08-27 20:41 [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Raul E Rangel
2020-08-27 20:41 ` [PATCH v2 2/2] Input: i8042 - Lock i8042_mutex before flushing Raul E Rangel
2020-10-28 20:35 ` [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Hans de Goede
@ 2020-12-07 6:40 ` Dmitry Torokhov
2 siblings, 0 replies; 4+ messages in thread
From: Dmitry Torokhov @ 2020-12-07 6:40 UTC (permalink / raw)
To: Raul E Rangel
Cc: linux-input, Shirish.S, Andy Shevchenko, Dan Murphy, Darren Hart,
Jacek Anaszewski, Lee, Chun-Yi, Pavel Machek, Rajat Jain,
Stephen Boyd, linux-kernel, linux-leds, platform-driver-x86
Hi Raul,
On Thu, Aug 27, 2020 at 02:41:53PM -0600, Raul E Rangel wrote:
> The i8042_mutex must be held by writers of the AUX and KBD ports, as
> well as users of i8042_command. There were a lot of users of
> i8042_command that were not calling i8042_lock_chip/i8042_unlock_chip.
> This resulted in i8042_commands being issues in between PS/2
> transactions.
>
> This change moves the mutex lock into i8042_command and removes the
> burden of locking the mutex from the callers.
I think there is a benefit for allowing users issue a sequence of
commands to i8042 without interruptions, so I would prefer keeping
i8042_[un]lock_chip() in place.
Given that the issue you were observing was caused by i8042_port_close()
interfering with probing, maybe we could do something like this:
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index abae23af0791..aff871001eda 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -344,6 +344,8 @@ int i8042_command(unsigned char *param, int command)
unsigned long flags;
int retval;
+ lockdep_assert_held(&i8042_mutex);
+
if (!i8042_present)
return -1;
@@ -364,6 +366,8 @@ static int i8042_kbd_write(struct serio *port, unsigned char c)
unsigned long flags;
int retval = 0;
+ lockdep_assert_held(&i8042_mutex);
+
spin_lock_irqsave(&i8042_lock, flags);
if (!(retval = i8042_wait_write())) {
@@ -411,6 +415,8 @@ static void i8042_port_close(struct serio *serio)
port_name = "KBD";
}
+ i8042_lock_chip();
+
i8042_ctr &= ~irq_bit;
if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
pr_warn("Can't write CTR while closing %s port\n", port_name);
@@ -422,6 +428,8 @@ static void i8042_port_close(struct serio *serio)
if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
pr_err("Can't reactivate %s port\n", port_name);
+ i8042_unlock_chip();
+
/*
* See if there is any data appeared while we were messing with
* port state.
Thanks.
--
Dmitry
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-12-07 6:41 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-27 20:41 [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Raul E Rangel
2020-08-27 20:41 ` [PATCH v2 2/2] Input: i8042 - Lock i8042_mutex before flushing Raul E Rangel
2020-10-28 20:35 ` [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands Hans de Goede
2020-12-07 6:40 ` Dmitry Torokhov
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).