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: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Fernando Guzman Lugo <x0095840@ti.com>
Acked-by: Hiroshi Doyu <hiroshi.doyu@nokia.com>
diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index cc58b44..459b319 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -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 @@
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;
@@ -249,41 +250,40 @@
int ret = 0;
struct omap_mbox_queue *mq;
- if (mbox->ops->startup) {
- mutex_lock(&mbox_configured_lock);
- if (!mbox_configured)
+ mutex_lock(&mbox_configured_lock);
+ if (!mbox_configured++) {
+ if (likely(mbox->ops->startup)) {
ret = mbox->ops->startup(mbox);
+ if (unlikely(ret))
+ goto fail_startup;
+ } else
+ goto fail_startup;
+ }
- if (ret) {
- mutex_unlock(&mbox_configured_lock);
- return ret;
+ if (!mbox->use_count++) {
+ ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
+ mbox->name, mbox);
+ if (unlikely(ret)) {
+ pr_err("failed to register mailbox interrupt:%d\n",
+ ret);
+ goto fail_request_irq;
}
- mbox_configured++;
- mutex_unlock(&mbox_configured_lock);
- }
+ mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
+ if (!mq) {
+ ret = -ENOMEM;
+ goto fail_alloc_txq;
+ }
+ mbox->txq = mq;
- 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);
- goto fail_request_irq;
+ mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
+ if (!mq) {
+ ret = -ENOMEM;
+ goto fail_alloc_rxq;
+ }
+ mbox->rxq = mq;
+ mq->mbox = mbox;
}
-
- mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
- if (!mq) {
- ret = -ENOMEM;
- goto fail_alloc_txq;
- }
- mbox->txq = mq;
-
- mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
- if (!mq) {
- ret = -ENOMEM;
- goto fail_alloc_rxq;
- }
- mbox->rxq = mq;
-
+ mutex_unlock(&mbox_configured_lock);
return 0;
fail_alloc_rxq:
@@ -293,29 +293,34 @@
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)
{
- 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);
+ mutex_lock(&mbox_configured_lock);
- if (mbox->ops->shutdown) {
- mutex_lock(&mbox_configured_lock);
- if (mbox_configured > 0)
- mbox_configured--;
- if (!mbox_configured)
- mbox->ops->shutdown(mbox);
- mutex_unlock(&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 (likely(mbox->ops->shutdown)) {
+ if (!--mbox_configured)
+ mbox->ops->shutdown(mbox);
+ }
+
+ 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 @@
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 @@
ret = PTR_ERR(mbox->dev);
goto err_out;
}
+
+ BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
}
return 0;