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Commit 58256307 authored by Kanigeri, Hari's avatar Kanigeri, Hari Committed by Hari Kanigeri
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OMAP: mailbox: add notification support for multiple readers 

In the current mailbox driver, the mailbox internal pointer for
callback can be directly manipulated by the Users, so a second
User can easily corrupt the first user's callback pointer.
The initial effort to correct this issue can be referred here:
https://patchwork.kernel.org/patch/107520/

Along with fixing the above stated issue, this patch  adds the
flexibility option to register notifications from
multiple readers to the events received on a mailbox instance.
The discussion regarding this can be referred here.
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg30671.html



Signed-off-by: default avatarHari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: default avatarFernando Guzman Lugo <x0095840@ti.com>
Acked-by: default avatarHiroshi Doyu <hiroshi.doyu@nokia.com>
parent a42743c2

arch/arm/plat-omap/include/plat/mailbox.h

+4 −3
Original line number Diff line number Diff line
@@ -46,7 +46,6 @@ struct omap_mbox_queue { 
	struct kfifo		fifo;

	struct work_struct	work;

	struct tasklet_struct	tasklet;

	int	(*callback)(void *);

	struct omap_mbox	*mbox;

	bool full;

};
@@ -58,13 +57,15 @@ struct omap_mbox { 
	struct omap_mbox_ops	*ops;

	struct device		*dev;

	void			*priv;

	int			use_count;

	struct blocking_notifier_head   notifier;

};



int omap_mbox_msg_send(struct omap_mbox *, mbox_msg_t msg);

void omap_mbox_init_seq(struct omap_mbox *);



struct omap_mbox *omap_mbox_get(const char *);

void omap_mbox_put(struct omap_mbox *);

struct omap_mbox *omap_mbox_get(const char *, struct notifier_block *nb);

void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb);



int omap_mbox_register(struct device *parent, struct omap_mbox **);

int omap_mbox_unregister(void);

arch/arm/plat-omap/mailbox.c

+57 −46
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/slab.h>

#include <linux/kfifo.h>

#include <linux/err.h>

#include <linux/notifier.h>



#include <plat/mailbox.h>
@@ -150,8 +151,8 @@ static void mbox_rx_work(struct work_struct *work) 
		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));

		WARN_ON(len != sizeof(msg));



		if (mq->callback)

			mq->callback((void *)msg);

		blocking_notifier_call_chain(&mq->mbox->notifier, len,

								(void *)msg);

		spin_lock_irq(&mq->lock);

		if (mq->full) {

			mq->full = false;
@@ -249,27 +250,24 @@ static int omap_mbox_startup(struct omap_mbox *mbox) 
	int ret = 0;

	struct omap_mbox_queue *mq;



	if (mbox->ops->startup) {

	mutex_lock(&mbox_configured_lock);

		if (!mbox_configured)

	if (!mbox_configured++) {

		if (likely(mbox->ops->startup)) {

			ret = mbox->ops->startup(mbox);



		if (ret) {

			mutex_unlock(&mbox_configured_lock);

			return ret;

		}

		mbox_configured++;

		mutex_unlock(&mbox_configured_lock);

			if (unlikely(ret))

				goto fail_startup;

		} else

			goto fail_startup;

	}



	if (!mbox->use_count++) {

		ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,

							mbox->name, mbox);

	if (ret) {

		printk(KERN_ERR

			"failed to register mailbox interrupt:%d\n", ret);

		if (unlikely(ret)) {

			pr_err("failed to register mailbox interrupt:%d\n",

									ret);

			goto fail_request_irq;

		}



		mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);

		if (!mq) {

			ret = -ENOMEM;
@@ -283,7 +281,9 @@ static int omap_mbox_startup(struct omap_mbox *mbox) 
			goto fail_alloc_rxq;

		}

		mbox->rxq = mq;



		mq->mbox = mbox;

	}

	mutex_unlock(&mbox_configured_lock);

	return 0;



fail_alloc_rxq:
@@ -293,29 +293,34 @@ fail_alloc_txq: 
fail_request_irq:

	if (mbox->ops->shutdown)

		mbox->ops->shutdown(mbox);



	mbox->use_count--;

fail_startup:

	mbox_configured--;

	mutex_unlock(&mbox_configured_lock);

	return ret;

}



static void omap_mbox_fini(struct omap_mbox *mbox)

{

	mutex_lock(&mbox_configured_lock);



	if (!--mbox->use_count) {

		free_irq(mbox->irq, mbox);

		tasklet_kill(&mbox->txq->tasklet);

		flush_work(&mbox->rxq->work);

		mbox_queue_free(mbox->txq);

		mbox_queue_free(mbox->rxq);

	}



	if (mbox->ops->shutdown) {

		mutex_lock(&mbox_configured_lock);

		if (mbox_configured > 0)

			mbox_configured--;

		if (!mbox_configured)

	if (likely(mbox->ops->shutdown)) {

		if (!--mbox_configured)

			mbox->ops->shutdown(mbox);

		mutex_unlock(&mbox_configured_lock);

	}



	mutex_unlock(&mbox_configured_lock);

}



struct omap_mbox *omap_mbox_get(const char *name)

struct omap_mbox *omap_mbox_get(const char *name, struct notifier_block *nb)

{

	struct omap_mbox *mbox;

	int ret;
@@ -334,12 +339,16 @@ struct omap_mbox *omap_mbox_get(const char *name) 
	if (ret)

		return ERR_PTR(-ENODEV);



	if (nb)

		blocking_notifier_chain_register(&mbox->notifier, nb);



	return mbox;

}

EXPORT_SYMBOL(omap_mbox_get);



void omap_mbox_put(struct omap_mbox *mbox)

void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb)

{

	blocking_notifier_chain_unregister(&mbox->notifier, nb);

	omap_mbox_fini(mbox);

}

EXPORT_SYMBOL(omap_mbox_put);
@@ -363,6 +372,8 @@ int omap_mbox_register(struct device *parent, struct omap_mbox **list) 
			ret = PTR_ERR(mbox->dev);

			goto err_out;

		}



		BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);

	}

	return 0;