| Message ID | 20200327112247.17691-2-clin@suse.com (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | ACPI: Flexible eject options to remove devices cautiously | expand |
On Fri, Mar 27, 2020 at 07:22:45PM +0800, Chester Lin wrote: > Add a request_offline attribute in order to tell the kernel if it's > required to send notifications to userland first while handling an eject > event. Userland will have to put the target device offline when this > attribute is set. > > Signed-off-by: Chester Lin <clin@suse.com> > --- > Documentation/ABI/testing/sysfs-bus-acpi | 16 ++++++++++ > drivers/acpi/device_sysfs.c | 40 +++++++++++++++++++++++- > drivers/acpi/scan.c | 39 +++++++++++++++++++---- > include/acpi/acpi_bus.h | 1 + > 4 files changed, 89 insertions(+), 7 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-acpi b/Documentation/ABI/testing/sysfs-bus-acpi > index e7898cfe5fb1..b9c467704889 100644 > --- a/Documentation/ABI/testing/sysfs-bus-acpi > +++ b/Documentation/ABI/testing/sysfs-bus-acpi > @@ -93,3 +93,19 @@ Description: > hardware, if the _HRV control method is present. It is mostly > useful for non-PCI devices because lspci can list the hardware > version for PCI devices. > + > +What: /sys/bus/acpi/devices/.../request_offline > +Date: Mar, 2020 > +Contact: Chester Lin <clin@suse.com> > +Description: > + (RW) Allows the userland to receive offline requests when > + devices are planning to be ejected. > + > + If bit [0] is clear, the kernel will automatically try putting > + the target offline before the target can be ejected. > + > + If bit [0] is set, a uevent will be sent to userland as an > + offline request and userland is responsible for handling offline > + operations before the target can be ejected. This approach > + provides flexibility while some applications could need more > + time to release resources. Don't use "bit", use 1/0/y/n/Y/N as the kernel will parse all of that for you with the kstrtobool() which was created just for this type of sysfs file. > diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c > index 96869f1538b9..453bd1b9edf5 100644 > --- a/drivers/acpi/device_sysfs.c > +++ b/drivers/acpi/device_sysfs.c > @@ -506,6 +506,37 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr, > } > static DEVICE_ATTR_RO(status); > > +static ssize_t request_offline_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct acpi_device *acpi_dev = to_acpi_device(dev); > + > + return sprintf(buf, "%u\n", acpi_dev->request_offline?1:0); > +} > + > +static ssize_t request_offline_store(struct device *dev, > + struct device_attribute *attr, const char *buf, size_t count) > +{ > + struct acpi_device *acpi_dev = to_acpi_device(dev); > + > + if (!count) > + return -EINVAL; > + > + switch (buf[0]) { > + case '0': > + acpi_dev->request_offline = false; > + break; > + case '1': > + acpi_dev->request_offline = true; > + break; > + default: > + return -EINVAL; > + } > + > + return count; > +} > +static DEVICE_ATTR_RW(request_offline); > + > /** > * acpi_device_setup_files - Create sysfs attributes of an ACPI device. > * @dev: ACPI device object. > @@ -580,6 +611,11 @@ int acpi_device_setup_files(struct acpi_device *dev) > result = device_create_file(&dev->dev, &dev_attr_eject); > if (result) > return result; > + > + result = device_create_file(&dev->dev, > + &dev_attr_request_offline); > + if (result) > + return result; > } > > if (dev->flags.power_manageable) { > @@ -623,8 +659,10 @@ void acpi_device_remove_files(struct acpi_device *dev) > /* > * If device has _EJ0, remove 'eject' file. > */ > - if (acpi_has_method(dev->handle, "_EJ0")) > + if (acpi_has_method(dev->handle, "_EJ0")) { > device_remove_file(&dev->dev, &dev_attr_eject); > + device_remove_file(&dev->dev, &dev_attr_request_offline); You all really should be using an attribute group and the is_visible() callback to handle all of this for you automatically. But that's a separate issue than this specific patch. > + } > > if (acpi_has_method(dev->handle, "_SUN")) > device_remove_file(&dev->dev, &dev_attr_sun); > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index 6d3448895382..1cb39c5360cf 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -145,6 +145,7 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, > struct acpi_device_physical_node *pn; > bool second_pass = (bool)data; > acpi_status status = AE_OK; > + char *envp[] = { "EVENT=offline", NULL }; > > if (acpi_bus_get_device(handle, &device)) > return AE_OK; > @@ -166,7 +167,18 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, > } else { > pn->put_online = false; > } > - ret = device_offline(pn->dev); > + > + /* Don't offline directly but need to notify userland first */ > + if (device->request_offline) { > + if (pn->dev->offline) > + ret = 0; > + else > + ret = kobject_uevent_env(&pn->dev->kobj, > + KOBJ_CHANGE, envp); So this is a userspace visable change with regards to kobject events? Are you sure that is ok?
Hi Greg, On Fri, Mar 27, 2020 at 12:38:42PM +0100, Greg KH wrote: > On Fri, Mar 27, 2020 at 07:22:45PM +0800, Chester Lin wrote: > > Add a request_offline attribute in order to tell the kernel if it's > > required to send notifications to userland first while handling an eject > > event. Userland will have to put the target device offline when this > > attribute is set. > > > > Signed-off-by: Chester Lin <clin@suse.com> > > --- > > Documentation/ABI/testing/sysfs-bus-acpi | 16 ++++++++++ > > drivers/acpi/device_sysfs.c | 40 +++++++++++++++++++++++- > > drivers/acpi/scan.c | 39 +++++++++++++++++++---- > > include/acpi/acpi_bus.h | 1 + > > 4 files changed, 89 insertions(+), 7 deletions(-) > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-acpi b/Documentation/ABI/testing/sysfs-bus-acpi > > index e7898cfe5fb1..b9c467704889 100644 > > --- a/Documentation/ABI/testing/sysfs-bus-acpi > > +++ b/Documentation/ABI/testing/sysfs-bus-acpi > > @@ -93,3 +93,19 @@ Description: > > hardware, if the _HRV control method is present. It is mostly > > useful for non-PCI devices because lspci can list the hardware > > version for PCI devices. > > + > > +What: /sys/bus/acpi/devices/.../request_offline > > +Date: Mar, 2020 > > +Contact: Chester Lin <clin@suse.com> > > +Description: > > + (RW) Allows the userland to receive offline requests when > > + devices are planning to be ejected. > > + > > + If bit [0] is clear, the kernel will automatically try putting > > + the target offline before the target can be ejected. > > + > > + If bit [0] is set, a uevent will be sent to userland as an > > + offline request and userland is responsible for handling offline > > + operations before the target can be ejected. This approach > > + provides flexibility while some applications could need more > > + time to release resources. > > Don't use "bit", use 1/0/y/n/Y/N as the kernel will parse all of that > for you with the kstrtobool() which was created just for this type of > sysfs file. > I'm sorry for this mistake. Based on my code they should be ASCII char '1' and '0' but not bitwise ops. I will fix this description. > > diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c > > index 96869f1538b9..453bd1b9edf5 100644 > > --- a/drivers/acpi/device_sysfs.c > > +++ b/drivers/acpi/device_sysfs.c > > @@ -506,6 +506,37 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr, > > } > > static DEVICE_ATTR_RO(status); > > > > +static ssize_t request_offline_show(struct device *dev, > > + struct device_attribute *attr, char *buf) > > +{ > > + struct acpi_device *acpi_dev = to_acpi_device(dev); > > + > > + return sprintf(buf, "%u\n", acpi_dev->request_offline?1:0); > > +} > > + > > +static ssize_t request_offline_store(struct device *dev, > > + struct device_attribute *attr, const char *buf, size_t count) > > +{ > > + struct acpi_device *acpi_dev = to_acpi_device(dev); > > + > > + if (!count) > > + return -EINVAL; > > + > > + switch (buf[0]) { > > + case '0': > > + acpi_dev->request_offline = false; > > + break; > > + case '1': > > + acpi_dev->request_offline = true; > > + break; > > + default: > > + return -EINVAL; > > + } > > + > > + return count; > > +} > > +static DEVICE_ATTR_RW(request_offline); > > + > > /** > > * acpi_device_setup_files - Create sysfs attributes of an ACPI device. > > * @dev: ACPI device object. > > @@ -580,6 +611,11 @@ int acpi_device_setup_files(struct acpi_device *dev) > > result = device_create_file(&dev->dev, &dev_attr_eject); > > if (result) > > return result; > > + > > + result = device_create_file(&dev->dev, > > + &dev_attr_request_offline); > > + if (result) > > + return result; > > } > > > > if (dev->flags.power_manageable) { > > @@ -623,8 +659,10 @@ void acpi_device_remove_files(struct acpi_device *dev) > > /* > > * If device has _EJ0, remove 'eject' file. > > */ > > - if (acpi_has_method(dev->handle, "_EJ0")) > > + if (acpi_has_method(dev->handle, "_EJ0")) { > > device_remove_file(&dev->dev, &dev_attr_eject); > > + device_remove_file(&dev->dev, &dev_attr_request_offline); > > You all really should be using an attribute group and the is_visible() > callback to handle all of this for you automatically. > > But that's a separate issue than this specific patch. > That sounds good to me. I will refine this part by declaring an attribute_group with a is_visible() callback. > > + } > > > > if (acpi_has_method(dev->handle, "_SUN")) > > device_remove_file(&dev->dev, &dev_attr_sun); > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index 6d3448895382..1cb39c5360cf 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -145,6 +145,7 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, > > struct acpi_device_physical_node *pn; > > bool second_pass = (bool)data; > > acpi_status status = AE_OK; > > + char *envp[] = { "EVENT=offline", NULL }; > > > > if (acpi_bus_get_device(handle, &device)) > > return AE_OK; > > @@ -166,7 +167,18 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, > > } else { > > pn->put_online = false; > > } > > - ret = device_offline(pn->dev); > > + > > + /* Don't offline directly but need to notify userland first */ > > + if (device->request_offline) { > > + if (pn->dev->offline) > > + ret = 0; > > + else > > + ret = kobject_uevent_env(&pn->dev->kobj, > > + KOBJ_CHANGE, envp); > > So this is a userspace visable change with regards to kobject events? > > Are you sure that is ok? > Since udev can see kobject events when devices are added, I haven't seen any risk if we make offline events visible too. Besides, normally online/eject attributes can only be written by root in userspace. Thanks, Chester Lin
On Mon, Mar 30, 2020 at 04:50:20PM +0800, Chester Lin wrote: > Hi Greg, > > On Fri, Mar 27, 2020 at 12:38:42PM +0100, Greg KH wrote: > > On Fri, Mar 27, 2020 at 07:22:45PM +0800, Chester Lin wrote: > > > Add a request_offline attribute in order to tell the kernel if it's > > > required to send notifications to userland first while handling an eject > > > event. Userland will have to put the target device offline when this > > > attribute is set. > > > > > > Signed-off-by: Chester Lin <clin@suse.com> > > > --- > > > Documentation/ABI/testing/sysfs-bus-acpi | 16 ++++++++++ > > > drivers/acpi/device_sysfs.c | 40 +++++++++++++++++++++++- > > > drivers/acpi/scan.c | 39 +++++++++++++++++++---- > > > include/acpi/acpi_bus.h | 1 + > > > 4 files changed, 89 insertions(+), 7 deletions(-) > > > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-acpi b/Documentation/ABI/testing/sysfs-bus-acpi > > > index e7898cfe5fb1..b9c467704889 100644 > > > --- a/Documentation/ABI/testing/sysfs-bus-acpi > > > +++ b/Documentation/ABI/testing/sysfs-bus-acpi > > > @@ -93,3 +93,19 @@ Description: > > > hardware, if the _HRV control method is present. It is mostly > > > useful for non-PCI devices because lspci can list the hardware > > > version for PCI devices. > > > + > > > +What: /sys/bus/acpi/devices/.../request_offline > > > +Date: Mar, 2020 > > > +Contact: Chester Lin <clin@suse.com> > > > +Description: > > > + (RW) Allows the userland to receive offline requests when > > > + devices are planning to be ejected. > > > + > > > + If bit [0] is clear, the kernel will automatically try putting > > > + the target offline before the target can be ejected. > > > + > > > + If bit [0] is set, a uevent will be sent to userland as an > > > + offline request and userland is responsible for handling offline > > > + operations before the target can be ejected. This approach > > > + provides flexibility while some applications could need more > > > + time to release resources. > > > > Don't use "bit", use 1/0/y/n/Y/N as the kernel will parse all of that > > for you with the kstrtobool() which was created just for this type of > > sysfs file. > > > > I'm sorry for this mistake. Based on my code they should be ASCII char '1' and > '0' but not bitwise ops. I will fix this description. > > > > diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c > > > index 96869f1538b9..453bd1b9edf5 100644 > > > --- a/drivers/acpi/device_sysfs.c > > > +++ b/drivers/acpi/device_sysfs.c > > > @@ -506,6 +506,37 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr, > > > } > > > static DEVICE_ATTR_RO(status); > > > > > > +static ssize_t request_offline_show(struct device *dev, > > > + struct device_attribute *attr, char *buf) > > > +{ > > > + struct acpi_device *acpi_dev = to_acpi_device(dev); > > > + > > > + return sprintf(buf, "%u\n", acpi_dev->request_offline?1:0); > > > +} > > > + > > > +static ssize_t request_offline_store(struct device *dev, > > > + struct device_attribute *attr, const char *buf, size_t count) > > > +{ > > > + struct acpi_device *acpi_dev = to_acpi_device(dev); > > > + > > > + if (!count) > > > + return -EINVAL; > > > + > > > + switch (buf[0]) { > > > + case '0': > > > + acpi_dev->request_offline = false; > > > + break; > > > + case '1': > > > + acpi_dev->request_offline = true; > > > + break; > > > + default: > > > + return -EINVAL; > > > + } > > > + > > > + return count; > > > +} > > > +static DEVICE_ATTR_RW(request_offline); > > > + > > > /** > > > * acpi_device_setup_files - Create sysfs attributes of an ACPI device. > > > * @dev: ACPI device object. > > > @@ -580,6 +611,11 @@ int acpi_device_setup_files(struct acpi_device *dev) > > > result = device_create_file(&dev->dev, &dev_attr_eject); > > > if (result) > > > return result; > > > + > > > + result = device_create_file(&dev->dev, > > > + &dev_attr_request_offline); > > > + if (result) > > > + return result; > > > } > > > > > > if (dev->flags.power_manageable) { > > > @@ -623,8 +659,10 @@ void acpi_device_remove_files(struct acpi_device *dev) > > > /* > > > * If device has _EJ0, remove 'eject' file. > > > */ > > > - if (acpi_has_method(dev->handle, "_EJ0")) > > > + if (acpi_has_method(dev->handle, "_EJ0")) { > > > device_remove_file(&dev->dev, &dev_attr_eject); > > > + device_remove_file(&dev->dev, &dev_attr_request_offline); > > > > You all really should be using an attribute group and the is_visible() > > callback to handle all of this for you automatically. > > > > But that's a separate issue than this specific patch. > > > > That sounds good to me. I will refine this part by declaring an attribute_group > with a is_visible() callback. > > > > + } > > > > > > if (acpi_has_method(dev->handle, "_SUN")) > > > device_remove_file(&dev->dev, &dev_attr_sun); > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > > index 6d3448895382..1cb39c5360cf 100644 > > > --- a/drivers/acpi/scan.c > > > +++ b/drivers/acpi/scan.c > > > @@ -145,6 +145,7 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, > > > struct acpi_device_physical_node *pn; > > > bool second_pass = (bool)data; > > > acpi_status status = AE_OK; > > > + char *envp[] = { "EVENT=offline", NULL }; > > > > > > if (acpi_bus_get_device(handle, &device)) > > > return AE_OK; > > > @@ -166,7 +167,18 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, > > > } else { > > > pn->put_online = false; > > > } > > > - ret = device_offline(pn->dev); > > > + > > > + /* Don't offline directly but need to notify userland first */ > > > + if (device->request_offline) { > > > + if (pn->dev->offline) > > > + ret = 0; > > > + else > > > + ret = kobject_uevent_env(&pn->dev->kobj, > > > + KOBJ_CHANGE, envp); > > > > So this is a userspace visable change with regards to kobject events? > > > > Are you sure that is ok? > > > > Since udev can see kobject events when devices are added, I haven't seen any > risk if we make offline events visible too. Besides, normally online/eject > attributes can only be written by root in userspace. > Correct my explanation here: So far udev can see several device events already, such as add, online, offline and remove. So I think it should not be risky if we send additional change events to userspace as notification. > Thanks, > Chester Lin
diff --git a/Documentation/ABI/testing/sysfs-bus-acpi b/Documentation/ABI/testing/sysfs-bus-acpi index e7898cfe5fb1..b9c467704889 100644 --- a/Documentation/ABI/testing/sysfs-bus-acpi +++ b/Documentation/ABI/testing/sysfs-bus-acpi @@ -93,3 +93,19 @@ Description: hardware, if the _HRV control method is present. It is mostly useful for non-PCI devices because lspci can list the hardware version for PCI devices. + +What: /sys/bus/acpi/devices/.../request_offline +Date: Mar, 2020 +Contact: Chester Lin <clin@suse.com> +Description: + (RW) Allows the userland to receive offline requests when + devices are planning to be ejected. + + If bit [0] is clear, the kernel will automatically try putting + the target offline before the target can be ejected. + + If bit [0] is set, a uevent will be sent to userland as an + offline request and userland is responsible for handling offline + operations before the target can be ejected. This approach + provides flexibility while some applications could need more + time to release resources. diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c index 96869f1538b9..453bd1b9edf5 100644 --- a/drivers/acpi/device_sysfs.c +++ b/drivers/acpi/device_sysfs.c @@ -506,6 +506,37 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(status); +static ssize_t request_offline_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct acpi_device *acpi_dev = to_acpi_device(dev); + + return sprintf(buf, "%u\n", acpi_dev->request_offline?1:0); +} + +static ssize_t request_offline_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + struct acpi_device *acpi_dev = to_acpi_device(dev); + + if (!count) + return -EINVAL; + + switch (buf[0]) { + case '0': + acpi_dev->request_offline = false; + break; + case '1': + acpi_dev->request_offline = true; + break; + default: + return -EINVAL; + } + + return count; +} +static DEVICE_ATTR_RW(request_offline); + /** * acpi_device_setup_files - Create sysfs attributes of an ACPI device. * @dev: ACPI device object. @@ -580,6 +611,11 @@ int acpi_device_setup_files(struct acpi_device *dev) result = device_create_file(&dev->dev, &dev_attr_eject); if (result) return result; + + result = device_create_file(&dev->dev, + &dev_attr_request_offline); + if (result) + return result; } if (dev->flags.power_manageable) { @@ -623,8 +659,10 @@ void acpi_device_remove_files(struct acpi_device *dev) /* * If device has _EJ0, remove 'eject' file. */ - if (acpi_has_method(dev->handle, "_EJ0")) + if (acpi_has_method(dev->handle, "_EJ0")) { device_remove_file(&dev->dev, &dev_attr_eject); + device_remove_file(&dev->dev, &dev_attr_request_offline); + } if (acpi_has_method(dev->handle, "_SUN")) device_remove_file(&dev->dev, &dev_attr_sun); diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index 6d3448895382..1cb39c5360cf 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -145,6 +145,7 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, struct acpi_device_physical_node *pn; bool second_pass = (bool)data; acpi_status status = AE_OK; + char *envp[] = { "EVENT=offline", NULL }; if (acpi_bus_get_device(handle, &device)) return AE_OK; @@ -166,7 +167,18 @@ static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data, } else { pn->put_online = false; } - ret = device_offline(pn->dev); + + /* Don't offline directly but need to notify userland first */ + if (device->request_offline) { + if (pn->dev->offline) + ret = 0; + else + ret = kobject_uevent_env(&pn->dev->kobj, + KOBJ_CHANGE, envp); + } else { + ret = device_offline(pn->dev); + } + if (ret >= 0) { pn->put_online = !ret; } else { @@ -188,6 +200,7 @@ static acpi_status acpi_bus_online(acpi_handle handle, u32 lvl, void *data, { struct acpi_device *device = NULL; struct acpi_device_physical_node *pn; + char *envp[] = { "EVENT=online", NULL }; if (acpi_bus_get_device(handle, &device)) return AE_OK; @@ -196,7 +209,12 @@ static acpi_status acpi_bus_online(acpi_handle handle, u32 lvl, void *data, list_for_each_entry(pn, &device->physical_node_list, node) if (pn->put_online) { - device_online(pn->dev); + if (device->request_offline) + kobject_uevent_env(&pn->dev->kobj, + KOBJ_CHANGE, envp); + else + device_online(pn->dev); + pn->put_online = false; } @@ -256,14 +274,23 @@ static int acpi_scan_hot_remove(struct acpi_device *device) acpi_handle handle = device->handle; unsigned long long sta; acpi_status status; + bool notify_single = false; + int error; - if (device->handler && device->handler->hotplug.demand_offline) { - if (!acpi_scan_is_offline(device, true)) + if (device->handler && device->handler->hotplug.demand_offline) + if (!device->request_offline) + notify_single = true; + + if (!acpi_scan_is_offline(device, notify_single)) { + if (notify_single) return -EBUSY; - } else { - int error = acpi_scan_try_to_offline(device); + + error = acpi_scan_try_to_offline(device); if (error) return error; + + if (device->request_offline) + return -EBUSY; } ACPI_DEBUG_PRINT((ACPI_DB_INFO, diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 0c23fd0548d1..7a29ea0a7d0e 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -375,6 +375,7 @@ struct acpi_device { struct list_head physical_node_list; struct mutex physical_node_lock; void (*remove)(struct acpi_device *); + bool request_offline; }; /* Non-device subnode */
Add a request_offline attribute in order to tell the kernel if it's required to send notifications to userland first while handling an eject event. Userland will have to put the target device offline when this attribute is set. Signed-off-by: Chester Lin <clin@suse.com> --- Documentation/ABI/testing/sysfs-bus-acpi | 16 ++++++++++ drivers/acpi/device_sysfs.c | 40 +++++++++++++++++++++++- drivers/acpi/scan.c | 39 +++++++++++++++++++---- include/acpi/acpi_bus.h | 1 + 4 files changed, 89 insertions(+), 7 deletions(-)