Hi Fernando,
From: "ext Guzman Lugo, Fernando" <x0095840@xxxxxx>
Subject: [PATCH 5/6] Mailbox: sleeping function called from invalid context fix
Date: Sat, 13 Feb 2010 02:42:16 +0100
> From e06b2716824f225747c4dc83ed2623d0160ae132 Mon Sep 17 00:00:00 2001
> From: Fernando Guzman Lugo <x0095840@xxxxxx>
> Date: Fri, 29 Jan 2010 17:12:24 -0600
> Subject: [PATCH] Mailbox: sleeping function called from invalid context fix
>
> This patch fixes this bug:
> BUG: sleeping function called from invalid context
> Inside omap2_mbox_startup is called clk_get_sys that can sleep,
> therefore omap2_mbox_startup can sleep but it is call in an atomic
> context . So the spinlock is change for a semaphore.
"mboxes_lock" is used to maintain the global list of mailbox
instances, which belong to a single mailbox H/W module, but they are
logical channels from S/W perspective. Both "->ops->startup()" and
"->ops->shutdown()" are being executed against the above single H/W
module, and a mailbox H/W module is totally __independent__ of the
registration of logical mailboxes, which are (un)registered with
"omap_mbox_(un)register()". IOW, a mbox instance can be registered at
anytime(before/after) H/W initialization. This H/W initialization is
taken care of by "mbox_configured" variable. So I might think that the
right solution is to introduce a new mutex lock __just for__ h/w
configuration as below:
Modified arch/arm/plat-omap/mailbox.c
diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index 8e90633..19530de 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -32,6 +32,7 @@ static struct omap_mbox *mboxes;
static DEFINE_RWLOCK(mboxes_lock);
static int mbox_configured;
+static DEFINE_MUTEX(mbox_configured_lock);
/* Mailbox FIFO handle functions */
static inline mbox_msg_t mbox_fifo_read(struct omap_mbox *mbox)
@@ -247,16 +248,16 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
struct omap_mbox_queue *mq;
if (likely(mbox->ops->startup)) {
- write_lock(&mboxes_lock);
+ mutex_lock(&mbox_configured_lock);
if (!mbox_configured)
ret = mbox->ops->startup(mbox);
if (unlikely(ret)) {
- write_unlock(&mboxes_lock);
+ mutex_unlock(&mbox_configured_lock);
return ret;
}
mbox_configured++;
- write_unlock(&mboxes_lock);
+ mutex_unlock(&mbox_configured_lock);
}
ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
@@ -302,12 +303,12 @@ static void omap_mbox_fini(struct omap_mbox *mbox)
free_irq(mbox->irq, mbox);
if (unlikely(mbox->ops->shutdown)) {
- write_lock(&mboxes_lock);
+ mutex_lock(&mbox_configured_lock);
if (mbox_configured > 0)
mbox_configured--;
if (!mbox_configured)
mbox->ops->shutdown(mbox);
- write_unlock(&mboxes_lock);
+ mutex_unlock(&mbox_configured_lock);
}
}
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
