omap: mailbox: convert rwlocks to spinlock

rwlocks are slower and have potential starvation issues
therefore spinlocks are generally preferred.

see also: http://lwn.net/Articles/364583/

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Kanigeri Hari <h-kanigeri2@ti.com>
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>

diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index c340216..fafe47b 100644 (file)
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -31,7 +31,7 @@
 
 static struct workqueue_struct *mboxd;
 static struct omap_mbox *mboxes;
-static DEFINE_RWLOCK(mboxes_lock);
+static DEFINE_SPINLOCK(mboxes_lock);
 static bool rq_full;
 
 static int mbox_configured;
@@ -341,14 +341,14 @@ struct omap_mbox *omap_mbox_get(const char *name)
        struct omap_mbox *mbox;
        int ret;
 
-       read_lock(&mboxes_lock);
+       spin_lock(&mboxes_lock);
        mbox = *(find_mboxes(name));
        if (mbox == NULL) {
-               read_unlock(&mboxes_lock);
+               spin_unlock(&mboxes_lock);
                return ERR_PTR(-ENOENT);
        }
 
-       read_unlock(&mboxes_lock);
+       spin_unlock(&mboxes_lock);
 
        ret = omap_mbox_startup(mbox);
        if (ret)
@@ -374,15 +374,15 @@ int omap_mbox_register(struct device *parent, struct omap_mbox *mbox)
        if (mbox->next)
                return -EBUSY;
 
-       write_lock(&mboxes_lock);
+       spin_lock(&mboxes_lock);
        tmp = find_mboxes(mbox->name);
        if (*tmp) {
                ret = -EBUSY;
-               write_unlock(&mboxes_lock);
+               spin_unlock(&mboxes_lock);
                goto err_find;
        }
        *tmp = mbox;
-       write_unlock(&mboxes_lock);
+       spin_unlock(&mboxes_lock);
 
        return 0;
 
@@ -395,18 +395,18 @@ int omap_mbox_unregister(struct omap_mbox *mbox)
 {
        struct omap_mbox **tmp;
 
-       write_lock(&mboxes_lock);
+       spin_lock(&mboxes_lock);
        tmp = &mboxes;
        while (*tmp) {
                if (mbox == *tmp) {
                        *tmp = mbox->next;
                        mbox->next = NULL;
-                       write_unlock(&mboxes_lock);
+                       spin_unlock(&mboxes_lock);
                        return 0;
                }
                tmp = &(*tmp)->next;
        }
-       write_unlock(&mboxes_lock);
+       spin_unlock(&mboxes_lock);
 
        return -EINVAL;
 }