Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757655Ab3EHRva (ORCPT ); Wed, 8 May 2013 13:51:30 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41099 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757286Ab3EHRv2 (ORCPT ); Wed, 8 May 2013 13:51:28 -0400 Date: Wed, 08 May 2013 19:51:29 +0200 Message-ID: From: Takashi Iwai To: Ming Lei Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH 1/3] firmware: Avoid superfluous usermodehelper lock In-Reply-To: References: <1367996197-32748-1-git-send-email-tiwai@suse.de> <1367996197-32748-2-git-send-email-tiwai@suse.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.2 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6365 Lines: 195 At Wed, 08 May 2013 18:37:01 +0200, Takashi Iwai wrote: > > At Wed, 08 May 2013 18:21:11 +0200, > Takashi Iwai wrote: > > > > At Wed, 8 May 2013 23:52:02 +0800, > > Ming Lei wrote: > > > > > > On Wed, May 8, 2013 at 2:56 PM, Takashi Iwai wrote: > > > > When a firmware file can be loaded directly, there is no good reason > > > > to lock usermodehelper. It's needed only when the direct fw load > > > > fails and falls back to the user-mode helper. > > > > > > I remembered that we discussed the problem before, :-) > > > > > > Some crazy drivers might call request_firmware inside resume callback > > > (for example, USB devices might be rebind in resume), with > > > usermodehelper_read_lock, we can find the mistake easily and log it. > > > > > > I am wondering if it is good to remove the usermodehelper lock. > > > > > > Could you let us know any benefit to do it? > > > > Well, the question is whether usermodehelper lock is really an > > appropriate stuff for *checking* the availability of direct fs > > access. I find it doesn't fit well any longer, in the situation where > > no actual user-space call is needed. Though, I'm not quite sure which > > lock or flag can be used instead... > > In other words, the first patch is no essential part of the fix. > I can revisit the second patch without this one and resend if > preferred. FWIW, below is the revised patch. It's alone without the patch 1 in the previous series. Takashi --- From: Takashi Iwai Subject: [PATCH v2] firmware: Avoid deadlock of usermodehelper lock at shutdown When a system goes to reboot/shutdown, it tries to disable the usermode helper via usermodehelper_disable(). This might be blocked when a driver tries to load a firmware beforehand and it's stuck by some reason. In this patch, the firmware class driver registers a reboot notifier so that it can abort all pending f/w bufs. Also enable a flag for avoiding the call of usermodehelper after the reboot/shutdown starts. Signed-off-by: Takashi Iwai --- drivers/base/firmware_class.c | 40 +++++++++++++++++++++++++++++++++------- 1 file changed, 33 insertions(+), 7 deletions(-) diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 4b1f926..972e535 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -27,6 +27,7 @@ #include #include #include +#include #include @@ -171,6 +172,7 @@ static struct firmware_buf *__allocate_fw_buf(const char *fw_name, strcpy(buf->fw_id, fw_name); buf->fwc = fwc; init_completion(&buf->completion); + INIT_LIST_HEAD(&buf->list); pr_debug("%s: fw-%s buf=%p\n", __func__, fw_name, buf); @@ -446,10 +448,9 @@ static struct firmware_priv *to_firmware_priv(struct device *dev) return container_of(dev, struct firmware_priv, dev); } -static void fw_load_abort(struct firmware_priv *fw_priv) +static void fw_load_abort(struct firmware_buf *buf) { - struct firmware_buf *buf = fw_priv->buf; - + list_del_init(&buf->list); set_bit(FW_STATUS_ABORT, &buf->status); complete_all(&buf->completion); } @@ -457,6 +458,24 @@ static void fw_load_abort(struct firmware_priv *fw_priv) #define is_fw_load_aborted(buf) \ test_bit(FW_STATUS_ABORT, &(buf)->status) +static LIST_HEAD(pending_fw_head); + +/* reboot notifier for avoid deadlock with usermode_lock */ +static int fw_shutdown_notify(struct notifier_block *unused1, + unsigned long unused2, void *unused3) +{ + mutex_lock(&fw_lock); + while (!list_empty(&pending_fw_head)) + fw_load_abort(list_first_entry(&pending_fw_head, + struct firmware_buf, list)); + mutex_unlock(&fw_lock); + return NOTIFY_DONE; +} + +static struct notifier_block fw_shutdown_nb = { + .notifier_call = fw_shutdown_notify, +}; + static ssize_t firmware_timeout_show(struct class *class, struct class_attribute *attr, char *buf) @@ -604,6 +623,7 @@ static ssize_t firmware_loading_store(struct device *dev, * is completed. * */ fw_map_pages_buf(fw_buf); + list_del_init(&fw_buf->list); complete_all(&fw_buf->completion); break; } @@ -612,7 +632,7 @@ static ssize_t firmware_loading_store(struct device *dev, dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading); /* fallthrough */ case -1: - fw_load_abort(fw_priv); + fw_load_abort(fw_buf); break; } out: @@ -680,7 +700,7 @@ static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size) new_pages = kmalloc(new_array_size * sizeof(void *), GFP_KERNEL); if (!new_pages) { - fw_load_abort(fw_priv); + fw_load_abort(buf); return -ENOMEM; } memcpy(new_pages, buf->pages, @@ -697,7 +717,7 @@ static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size) alloc_page(GFP_KERNEL | __GFP_HIGHMEM); if (!buf->pages[buf->nr_pages]) { - fw_load_abort(fw_priv); + fw_load_abort(buf); return -ENOMEM; } buf->nr_pages++; @@ -781,7 +801,7 @@ static void firmware_class_timeout_work(struct work_struct *work) mutex_unlock(&fw_lock); return; } - fw_load_abort(fw_priv); + fw_load_abort(fw_priv->buf); mutex_unlock(&fw_lock); } @@ -857,6 +877,10 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent, kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD); } + mutex_lock(&fw_lock); + list_add(&buf->list, &pending_fw_head); + mutex_unlock(&fw_lock); + wait_for_completion(&buf->completion); cancel_delayed_work_sync(&fw_priv->timeout_work); @@ -1517,6 +1541,7 @@ static int __init firmware_class_init(void) { fw_cache_init(); #ifdef CONFIG_FW_LOADER_USER_HELPER + register_reboot_notifier(&fw_shutdown_nb); return class_register(&firmware_class); #else return 0; @@ -1530,6 +1555,7 @@ static void __exit firmware_class_exit(void) unregister_pm_notifier(&fw_cache.pm_notify); #endif #ifdef CONFIG_FW_LOADER_USER_HELPER + unregister_reboot_notifier(&fw_shutdown_nb); class_unregister(&firmware_class); #endif } -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/