Hi Fernando, From: "ext Guzman Lugo, Fernando" <[email protected]> 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 <[email protected]> > 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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
