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Date: Sat, 27 Feb 2010 18:57:02 -0800 From: ebiederm@...ssion.com (Eric W. Biederman) To: Evgeniy Polyakov <zbr@...emap.net> Cc: <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org> Subject: Why does connector use a work queue??? These days netlink callbacks for messages happen in the context of the process who sent the message. Things like permission checks are much more complicated if we don't use that process context. I was looking at removing NETLINK_CB(skb).eff_cap but I discovered that connected takes the netlink messages, them from their perfectly good process context, and puts the into a workqueue for reasons that are not apparent to me. Unless I am misreading something we should just be able to remove the work queues and greatly simplify the connector code. Something like: diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c index 537c29a..4c9af0a 100644 --- a/drivers/connector/connector.c +++ b/drivers/connector/connector.c @@ -120,52 +120,28 @@ EXPORT_SYMBOL_GPL(cn_netlink_send); */ static int cn_call_callback(struct sk_buff *skb) { - struct cn_callback_entry *__cbq, *__new_cbq; + struct cn_callback_entry *__cbq; struct cn_dev *dev = &cdev; struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb)); int err = -ENODEV; + void (*callback)(struct cn_msg *req, struct netlink_skb_parms *nsp); + callback = NULL; spin_lock_bh(&dev->cbdev->queue_lock); list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) { if (cn_cb_equal(&__cbq->id.id, &msg->id)) { - if (likely(!work_pending(&__cbq->work) && - __cbq->data.skb == NULL)) { - __cbq->data.skb = skb; - - if (queue_cn_work(__cbq, &__cbq->work)) - err = 0; - else - err = -EINVAL; - } else { - struct cn_callback_data *d; - - err = -ENOMEM; - __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC); - if (__new_cbq) { - d = &__new_cbq->data; - d->skb = skb; - d->callback = __cbq->data.callback; - d->free = __new_cbq; - - __new_cbq->pdev = __cbq->pdev; - - INIT_WORK(&__new_cbq->work, - &cn_queue_wrapper); - - if (queue_cn_work(__new_cbq, - &__new_cbq->work)) - err = 0; - else { - kfree(__new_cbq); - err = -EINVAL; - } - } - } + callback = __cbq->data.callback; + err = 0; break; } } spin_unlock_bh(&dev->cbdev->queue_lock); + if (!err) { + callback(msg, &NETLINK_CB(skb)); + kfree_skb(skb); + } + return err; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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