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greybus: operation: make cancellation synchronous 

Make sure to wait for the operation to become inactive before returning
after having cancelled an operation.

This makes sure that any ongoing operation completion callbacks have
finished.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
hifive-unleashed-5.1
Johan Hovold 2015-07-14 15:43:26 +02:00 committed by Greg Kroah-Hartman
parent 3eeac7e37c
commit fd7134a3cd
3 changed files with 23 additions and 3 deletions
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1
drivers/staging/greybus/connection.c
View File

@ -227,7 +227,6 @@ void gb_connection_destroy(struct gb_connection *connection)
if (WARN_ON(!connection))
return;
/* XXX Need to wait for any outstanding requests to complete */
if (WARN_ON(!list_empty(&connection->operations))) {
list_for_each_entry_safe(operation, next,
&connection->operations, links)

24
drivers/staging/greybus/operation.c
View File

@ -10,6 +10,8 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include "greybus.h"
@ -23,6 +25,9 @@ static struct kmem_cache *gb_message_cache;
/* Workqueue to handle Greybus operation completions. */
static struct workqueue_struct *gb_operation_workqueue;
/* Wait queue for synchronous cancellations. */
static DECLARE_WAIT_QUEUE_HEAD(gb_operation_cancellation_queue);
/*
* Protects access to connection operations lists, as well as
* updates to operation->errno.
@ -41,7 +46,15 @@ static inline void gb_operation_get_active(struct gb_operation *operation)
/* Caller holds operation reference. */
static inline void gb_operation_put_active(struct gb_operation *operation)
{
atomic_dec(&operation->active);
if (atomic_dec_and_test(&operation->active)) {
if (atomic_read(&operation->waiters))
wake_up(&gb_operation_cancellation_queue);
}
}
static inline bool gb_operation_is_active(struct gb_operation *operation)
{
return atomic_read(&operation->active);
}
/*
@ -463,6 +476,7 @@ gb_operation_create_common(struct gb_connection *connection, u8 type,
init_completion(&operation->completion);
kref_init(&operation->kref);
atomic_set(&operation->active, 0);
atomic_set(&operation->waiters, 0);
spin_lock_irqsave(&gb_operations_lock, flags);
list_add_tail(&operation->links, &connection->operations);
@ -873,7 +887,8 @@ void gb_connection_recv(struct gb_connection *connection,
}
/*
* Cancel an operation, and record the given error to indicate why.
* Cancel an operation synchronously, and record the given error to indicate
* why.
*/
void gb_operation_cancel(struct gb_operation *operation, int errno)
{
@ -890,6 +905,11 @@ void gb_operation_cancel(struct gb_operation *operation, int errno)
gb_operation_put(operation);
}
}
atomic_inc(&operation->waiters);
wait_event(gb_operation_cancellation_queue,
!gb_operation_is_active(operation));
atomic_dec(&operation->waiters);
}
EXPORT_SYMBOL_GPL(gb_operation_cancel);

1
drivers/staging/greybus/operation.h
View File

@ -128,6 +128,7 @@ struct gb_operation {
struct kref kref;
atomic_t active;
atomic_t waiters;
struct list_head links; /* connection->operations */
};