From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sipsolutions.net (crystal.sipsolutions.net [195.210.38.204]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 75BC267B4E for ; Fri, 9 Jun 2006 21:39:44 +1000 (EST) Subject: Re: pmf_register_irq_client gives sleep with locks held warning From: Johannes Berg To: Benjamin Herrenschmidt In-Reply-To: <1149123574.15446.15.camel@localhost.localdomain> References: <1149020341.5128.7.camel@johannes> <1149123574.15446.15.camel@localhost.localdomain> Content-Type: text/plain Date: Thu, 08 Jun 2006 20:58:17 +0200 Message-Id: <1149793098.11525.34.camel@johannes> Mime-Version: 1.0 Cc: Andrew Morton , linuxppc-dev list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2006-06-01 at 10:59 +1000, Benjamin Herrenschmidt wrote: > This fixes request_irq() potentially called from atomic context. > [...] Sorry, almost forgot about this. I don't think your patch is right, it seems to me that now pmf_unregister_irq_client races against pmf_do_irq: what happens when an interrupt comes in right in the middle of the list_del()? It might actually not do any harm due to the way list_del() and pmf_do_irq() work and the fact that client->handler() must still be prepared to be called... But I'd rather make it explicit. By the way, what do I do when like this I change a patch? Do I rely on your Signed-off-by and simply put mine instead (like I did now)? Anyway, here's a changed patch that illustrates my point. I've tested it and it works and as expected fixes the problem :) --- This fixes request_irq() being called with interrupts disabled in the powermac platform function code when registering the first irq client for a given platform function. Cc: Benjamin Herrenschmidt Signed-off-by: Johannes Berg --- a/arch/powerpc/platforms/powermac/pfunc_core.c +++ b/arch/powerpc/platforms/powermac/pfunc_core.c @@ -11,6 +11,7 @@ #include #include #include #include +#include #include #include @@ -546,6 +547,7 @@ struct pmf_device { static LIST_HEAD(pmf_devices); static spinlock_t pmf_lock = SPIN_LOCK_UNLOCKED; +static DEFINE_MUTEX(pmf_irq_mutex); static void pmf_release_device(struct kref *kref) { @@ -864,16 +866,25 @@ int pmf_register_irq_client(struct devic spin_lock_irqsave(&pmf_lock, flags); func = __pmf_find_function(target, name, PMF_FLAGS_INT_GEN); - if (func == NULL) { - spin_unlock_irqrestore(&pmf_lock, flags); + if (func) + func = pmf_get_function(func); + spin_unlock_irqrestore(&pmf_lock, flags); + if (func == NULL) return -ENODEV; - } + + /* guard against manipulations of list */ + mutex_lock(&pmf_irq_mutex); if (list_empty(&func->irq_clients)) func->dev->handlers->irq_enable(func); + + /* guard against pmf_do_irq while changing list */ + spin_lock_irqsave(&pmf_lock, flags); list_add(&client->link, &func->irq_clients); - client->func = func; spin_unlock_irqrestore(&pmf_lock, flags); + client->func = func; + mutex_unlock(&pmf_irq_mutex); + return 0; } EXPORT_SYMBOL_GPL(pmf_register_irq_client); @@ -885,12 +896,19 @@ void pmf_unregister_irq_client(struct pm BUG_ON(func == NULL); - spin_lock_irqsave(&pmf_lock, flags); + /* guard against manipulations of list */ + mutex_lock(&pmf_irq_mutex); client->func = NULL; + + /* guard against pmf_do_irq while changing list */ + spin_lock_irqsave(&pmf_lock, flags); list_del(&client->link); + spin_unlock_irqrestore(&pmf_lock, flags); + if (list_empty(&func->irq_clients)) func->dev->handlers->irq_disable(func); - spin_unlock_irqrestore(&pmf_lock, flags); + mutex_unlock(&pmf_irq_mutex); + pmf_put_function(func); } EXPORT_SYMBOL_GPL(pmf_unregister_irq_client);