diff mbox series

[PATCHv2] base: force NOIO allocations during unplug

Message ID 20200916191544.5104-1-oneukum@suse.com
State New
Headers show
Series [PATCHv2] base: force NOIO allocations during unplug | expand

Commit Message

Oliver Neukum Sept. 16, 2020, 7:15 p.m. UTC
There is one overlooked situation under which a driver
must not do IO to allocate memory. You cannot do that
while disconnecting a device. A device being disconnected
is no longer functional in most cases, yet IO may fail
only when the handler runs.

v2: extended section for NOIO until after second notifier chain

Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/base/core.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Greg KH Sept. 17, 2020, 6:41 a.m. UTC | #1
On Wed, Sep 16, 2020 at 09:15:44PM +0200, Oliver Neukum wrote:
> There is one overlooked situation under which a driver

> must not do IO to allocate memory. You cannot do that

> while disconnecting a device. A device being disconnected

> is no longer functional in most cases, yet IO may fail

> only when the handler runs.

> 

> v2: extended section for NOIO until after second notifier chain

> 

> Signed-off-by: Oliver Neukum <oneukum@suse.com>

> ---

>  drivers/base/core.c | 4 ++++

>  1 file changed, 4 insertions(+)

> 

> diff --git a/drivers/base/core.c b/drivers/base/core.c

> index bb5806a2bd4c..b79783454293 100644

> --- a/drivers/base/core.c

> +++ b/drivers/base/core.c

> @@ -26,6 +26,7 @@

>  #include <linux/pm_runtime.h>

>  #include <linux/netdevice.h>

>  #include <linux/sched/signal.h>

> +#include <linux/sched/mm.h>

>  #include <linux/sysfs.h>

>  

>  #include "base.h"

> @@ -3062,6 +3063,7 @@ void device_del(struct device *dev)

>  	struct device *parent = dev->parent;

>  	struct kobject *glue_dir = NULL;

>  	struct class_interface *class_intf;

> +	unsigned int noio_flag;

>  

>  	device_lock(dev);

>  	kill_device(dev);

> @@ -3073,6 +3075,7 @@ void device_del(struct device *dev)

>  	/* Notify clients of device removal.  This call must come

>  	 * before dpm_sysfs_remove().

>  	 */

> +	noio_flag = memalloc_noio_save();

>  	if (dev->bus)

>  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,

>  					     BUS_NOTIFY_DEL_DEVICE, dev);

> @@ -3114,6 +3117,7 @@ void device_del(struct device *dev)

>  	glue_dir = get_glue_dir(dev);

>  	kobject_del(&dev->kobj);

>  	cleanup_glue_dir(dev, glue_dir);

> +	memalloc_noio_restore(noio_flag);

>  	put_device(parent);

>  }

>  EXPORT_SYMBOL_GPL(device_del);

> -- 

> 2.16.4

> 


Thanks, now queued up.

greg k-h
diff mbox series

Patch

diff --git a/drivers/base/core.c b/drivers/base/core.c
index bb5806a2bd4c..b79783454293 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -26,6 +26,7 @@ 
 #include <linux/pm_runtime.h>
 #include <linux/netdevice.h>
 #include <linux/sched/signal.h>
+#include <linux/sched/mm.h>
 #include <linux/sysfs.h>
 
 #include "base.h"
@@ -3062,6 +3063,7 @@  void device_del(struct device *dev)
 	struct device *parent = dev->parent;
 	struct kobject *glue_dir = NULL;
 	struct class_interface *class_intf;
+	unsigned int noio_flag;
 
 	device_lock(dev);
 	kill_device(dev);
@@ -3073,6 +3075,7 @@  void device_del(struct device *dev)
 	/* Notify clients of device removal.  This call must come
 	 * before dpm_sysfs_remove().
 	 */
+	noio_flag = memalloc_noio_save();
 	if (dev->bus)
 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DEL_DEVICE, dev);
@@ -3114,6 +3117,7 @@  void device_del(struct device *dev)
 	glue_dir = get_glue_dir(dev);
 	kobject_del(&dev->kobj);
 	cleanup_glue_dir(dev, glue_dir);
+	memalloc_noio_restore(noio_flag);
 	put_device(parent);
 }
 EXPORT_SYMBOL_GPL(device_del);