lkml.org 
[lkml]   [2007]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] make attribute_container_unregister() unconditionally wait for list empty
From
Date
James,

>> > > Isn't a better way to handle it simply to give
>> > > transport_container_unregister() the semantics everyone is expecting
>> > > (i.e. to wait for everything to be tidied up and gone)? That way none
>> > > of the transport classes needs updating, and we don't have to handle the
>> > > rather nasty release and unload races.
>
> I was thinking of a wait_event driven system checking for
> list_empty(cont->containers.k_list)

I hope this is more in line with what you were thinking.....
-- james s


Signed-off-by: James Smart <James.Smart@emulex.com>


diff -upNr a/drivers/base/attribute_container.c b/drivers/base/attribute_container.c
--- a/drivers/base/attribute_container.c 2007-08-16 02:59:50.000000000 -0400
+++ b/drivers/base/attribute_container.c 2007-08-17 05:02:03.000000000 -0400
@@ -19,6 +19,7 @@
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/sched.h>

#include "base.h"

@@ -75,6 +76,8 @@ int
attribute_container_register(struct attribute_container *cont)
{
INIT_LIST_HEAD(&cont->node);
+ init_waitqueue_head(&cont->cont_wait);
+ cont->flags &= ~ATTRIBUTE_CONTAINER_EVENT_PENDING;
klist_init(&cont->containers,internal_container_klist_get,
internal_container_klist_put);

@@ -89,23 +92,26 @@ EXPORT_SYMBOL_GPL(attribute_container_re
/**
* attribute_container_unregister - remove a container registration
*
+ * Semantics have now changed - we never return until the list goes empty
+ *
* @cont: previously registered container to remove
*/
int
attribute_container_unregister(struct attribute_container *cont)
{
- int retval = -EBUSY;
mutex_lock(&attribute_container_mutex);
spin_lock(&cont->containers.k_lock);
- if (!list_empty(&cont->containers.k_list))
- goto out;
- retval = 0;
- list_del(&cont->node);
- out:
+ if (!list_empty(&cont->containers.k_list))
+ cont->flags |= ATTRIBUTE_CONTAINER_EVENT_PENDING;
spin_unlock(&cont->containers.k_lock);
mutex_unlock(&attribute_container_mutex);
- return retval;
-
+ wait_event(cont->cont_wait,
+ !(cont->flags & ATTRIBUTE_CONTAINER_EVENT_PENDING));
+ mutex_lock(&attribute_container_mutex);
+ list_del(&cont->node);
+ mutex_unlock(&attribute_container_mutex);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(attribute_container_unregister);

@@ -234,6 +240,15 @@ attribute_container_remove_device(struct
class_device_unregister(&ic->classdev);
}
}
+
+ if (cont->flags & ATTRIBUTE_CONTAINER_EVENT_PENDING) {
+ spin_lock(&cont->containers.k_lock);
+ if (list_empty(&cont->containers.k_list))
+ cont->flags &=
+ ~ATTRIBUTE_CONTAINER_EVENT_PENDING;
+ spin_unlock(&cont->containers.k_lock);
+ wake_up(&cont->cont_wait);
+ }
}
mutex_unlock(&attribute_container_mutex);
}
diff -upNr a/include/linux/attribute_container.h b/include/linux/attribute_container.h
--- a/include/linux/attribute_container.h 2007-08-16 03:00:10.000000000 -0400
+++ b/include/linux/attribute_container.h 2007-08-17 03:46:01.000000000 -0400
@@ -20,7 +20,9 @@ struct attribute_container {
struct class_device_attribute **attrs;
int (*match)(struct attribute_container *, struct device *);
#define ATTRIBUTE_CONTAINER_NO_CLASSDEVS 0x01
+#define ATTRIBUTE_CONTAINER_EVENT_PENDING 0x02
unsigned long flags;
+ wait_queue_head_t cont_wait;
};

static inline int


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-08-15 17:43    [from the cache]
©2003-2011 Jasper Spaans