From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755947Ab0CJAKX (ORCPT ); Tue, 9 Mar 2010 19:10:23 -0500 Received: from smtp-out.google.com ([216.239.33.17]:43550 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754989Ab0CJAKV (ORCPT ); Tue, 9 Mar 2010 19:10:21 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:to:cc:subject:date:message-id:x-mailer:x-system-of-record; b=RRdT3XrKGLUDRGftxV3HpJV855gYM7XS1NojPWy2wtcqSVJ4I67+l9fr4KNBcwFBB E1UqNFdKETHr8qrzcJPDw== From: y@google.com Cc: android-kernel@googlegroups.com, Chunqiu Wang , Mike Chan , Tony Lindgren , Russell King , Rajendra Nayak , Tero Kristo , Kalle Jokiniemi , Jouni Hogander , Kevin Hilman , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] omap: resource: Add per-resource mutex for OMAP resource framework Date: Tue, 9 Mar 2010 16:09:12 -0800 Message-Id: <1268179753-4063-1-git-send-email-y> X-Mailer: git-send-email 1.6.6.2 X-System-Of-Record: true To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chunqiu Wang Current OMAP resource fwk uses a global res_mutex for resource_request and resource_release calls for all the available resources.It may cause dead lock if resource_request/resource_release is called recursively. For current OMAP3 VDD1/VDD2 resource, the change_level implementation is mach-omap2/resource34xx.c/set_opp(), when using resource_release to remove vdd1 constraint, this function may call resource_release again to release Vdd2 constrait if target vdd1 level is less than OPP3. in this scenario, the global res_mutex down operation will be called again, this will cause the second down operation hang there. To fix the problem, per-resource mutex is added to avoid hangup when resource_request/resource_release is called recursively. Signed-off-by: Chunqiu Wang Signed-off-by: Mike Chan --- arch/arm/plat-omap/include/plat/resource.h | 2 ++ arch/arm/plat-omap/resource.c | 21 ++++++++++----------- 2 files changed, 12 insertions(+), 11 deletions(-) diff --git a/arch/arm/plat-omap/include/plat/resource.h b/arch/arm/plat-omap/include/plat/resource.h index 9acebcc..b5aff1f 100644 --- a/arch/arm/plat-omap/include/plat/resource.h +++ b/arch/arm/plat-omap/include/plat/resource.h @@ -54,6 +54,8 @@ struct shared_resource { /* Shared resource operations */ struct shared_resource_ops *ops; struct list_head node; + /* Protect each resource */ + struct mutex resource_mutex; }; struct shared_resource_ops { diff --git a/arch/arm/plat-omap/resource.c b/arch/arm/plat-omap/resource.c index f1cdecf..0a7b79b 100644 --- a/arch/arm/plat-omap/resource.c +++ b/arch/arm/plat-omap/resource.c @@ -277,6 +277,7 @@ int resource_register(struct shared_resource *resp) } INIT_LIST_HEAD(&resp->users_list); + mutex_init(&resp->resource_mutex); /* Add the resource to the resource list */ list_add(&resp->node, &res_list); @@ -339,14 +340,13 @@ int resource_request(const char *name, struct device *dev, struct users_list *user; int found = 0, ret = 0; - down(&res_mutex); - resp = _resource_lookup(name); + resp = resource_lookup(name); if (!resp) { printk(KERN_ERR "resource_request: Invalid resource name\n"); - ret = -EINVAL; - goto res_unlock; + return -EINVAL; } + mutex_lock(&resp->resource_mutex); /* Call the resource specific validate function */ if (resp->ops->validate_level) { ret = resp->ops->validate_level(resp, level); @@ -375,7 +375,7 @@ int resource_request(const char *name, struct device *dev, user->level = level; res_unlock: - up(&res_mutex); + mutex_unlock(&resp->resource_mutex); /* * Recompute and set the current level for the resource. * NOTE: update_resource level moved out of spin_lock, as it may call @@ -406,14 +406,13 @@ int resource_release(const char *name, struct device *dev) struct users_list *user; int found = 0, ret = 0; - down(&res_mutex); - resp = _resource_lookup(name); + resp = resource_lookup(name); if (!resp) { printk(KERN_ERR "resource_release: Invalid resource name\n"); - ret = -EINVAL; - goto res_unlock; + return -EINVAL; } + mutex_lock(&resp->resource_mutex); list_for_each_entry(user, &resp->users_list, node) { if (user->dev == dev) { found = 1; @@ -434,7 +433,7 @@ int resource_release(const char *name, struct device *dev) /* Recompute and set the current level for the resource */ ret = update_resource_level(resp); res_unlock: - up(&res_mutex); + mutex_unlock(&resp->resource_mutex); return ret; } EXPORT_SYMBOL(resource_release); @@ -458,7 +457,7 @@ int resource_get_level(const char *name) up(&res_mutex); return -EINVAL; } - ret = resp->curr_level; + ret = resp->curr_level; up(&res_mutex); return ret; } -- 1.6.6.2