[PATCH 6/7] omap:mailbox-add notification support for multiple readers
Hari Kanigeri
h-kanigeri2 at ti.com
Thu Oct 14 22:13:27 EDT 2010
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 at ti.com>
Signed-off-by: Fernando Guzman Lugo <x0095840 at ti.com>
---
arch/arm/plat-omap/include/plat/mailbox.h | 9 ++-
arch/arm/plat-omap/mailbox.c | 102 ++++++++++++++++-------------
2 files changed, 62 insertions(+), 49 deletions(-)
diff --git a/arch/arm/plat-omap/include/plat/mailbox.h b/arch/arm/plat-omap/include/plat/mailbox.h
index 13f2ef3..4c35654 100644
--- a/arch/arm/plat-omap/include/plat/mailbox.h
+++ b/arch/arm/plat-omap/include/plat/mailbox.h
@@ -8,6 +8,7 @@
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kfifo.h>
+#include <linux/notifier.h>
typedef u32 mbox_msg_t;
struct omap_mbox;
@@ -46,7 +47,6 @@ 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 +58,16 @@ 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);
diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index 1727548..35956f5 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 @@ 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);
if (mq->full) {
mq->full = false;
omap_mbox_enable_irq(mq->mbox, IRQ_RX);
@@ -202,7 +203,7 @@ nomem:
static irqreturn_t mbox_interrupt(int irq, void *p)
{
- struct omap_mbox *mbox = p;
+ int i;
for (i = 0; mboxes[i]; i++) {
struct omap_mbox *mbox = mboxes[i];
@@ -252,41 +253,39 @@ 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)
+ mutex_lock(&mbox_configured_lock);
+ if (!mbox_configured++) {
+ if (likely(mbox->ops->startup)) {
ret = mbox->ops->startup(mbox);
-
- if (ret) {
- mutex_unlock(&mbox_configured_lock);
- return ret;
+ if (unlikely(ret))
+ goto fail_startup;
}
- mbox_configured++;
- mutex_unlock(&mbox_configured_lock);
}
- 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, NULL, mbox_tx_tasklet);
- if (!mq) {
- ret = -ENOMEM;
- goto fail_alloc_txq;
- }
- mbox->txq = mq;
+ 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;
+ }
+ 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;
+ mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
+ if (!mq) {
+ ret = -ENOMEM;
+ goto fail_alloc_rxq;
+ }
+ mbox->rxq = mq;
+ mq->mbox = mbox;
}
- mbox->rxq = mq;
-
+ mutex_unlock(&mbox_configured_lock);
return 0;
fail_alloc_rxq:
@@ -296,29 +295,36 @@ 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)
{
- 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)
+ mutex_lock(&mbox_configured_lock);
+
+ if (!--mbox->use_count) {
+ 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) {
+ free_irq(mbox->irq, mbox);
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;
@@ -336,13 +342,16 @@ struct omap_mbox *omap_mbox_get(const char *name)
ret = omap_mbox_startup(mbox);
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);
@@ -366,6 +375,7 @@ 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;
--
1.7.0
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