From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753807Ab3KTAFL (ORCPT ); Tue, 19 Nov 2013 19:05:11 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:52659 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753783Ab3KTAFF (ORCPT ); Tue, 19 Nov 2013 19:05:05 -0500 From: "Rafael J. Wysocki" To: shuah.kh@samsung.com Cc: Greg KH , len.brown@intel.com, pavel@ucw.cz, anton@enomsg.org, dwmw2@infradead.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, shuahkhan@gmail.com Subject: Re: [PATCH 2/2] power: Change device_wakeup_enable() to WARN_ON on null dev_name(dev) Date: Wed, 20 Nov 2013 01:17:44 +0100 Message-ID: <8369024.IvrLpoEn0X@vostro.rjw.lan> User-Agent: KMail/4.10.5 (Linux/3.12.0-rc6+; KDE/4.10.5; x86_64; ; ) In-Reply-To: <3131384.OBt4qgLdzO@vostro.rjw.lan> References: <528BF9DB.6050308@samsung.com> <3131384.OBt4qgLdzO@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, November 20, 2013 01:12:17 AM Rafael J. Wysocki wrote: > On Tuesday, November 19, 2013 04:52:59 PM Shuah Khan wrote: > > On 11/19/2013 04:56 PM, Rafael J. Wysocki wrote: > > > On Tuesday, November 19, 2013 03:14:01 PM Greg KH wrote: > > >> On Tue, Nov 19, 2013 at 09:05:46AM -0700, Shuah Khan wrote: > > >>> device_wakeup_enable() uses dev_name(dev) as the wakeup source name. > > >>> When it gets called with a device with its name not yet set, ws structure > > >>> with ws->name = NULL gets created. > > >>> > > >>> When kernel is booted with wakeup_source_activate enabled, it will panic > > >>> when the trace point code tries to dereferences ws->name. > > >>> > > >>> Change device_wakeup_enable() to WARN_ON on dev_name(dev) null condition > > >>> to detect driver bugs that result in calling device_wakeup_enable() before > > >>> device is fully initialized with its name in device_wakeup_enable(). > > >>> > > >>> This change without the power_supply_register() fix will result in early > > >>> boot panics when AC Adapter and Battery device drivers try to register > > >>> wakeup source. > > >>> > > >>> The following panic resulted from power_supply_register() registering > > >>> wakeup source with a null device name. > > >>> > > >>> [ 819.769934] device: 'BAT1': device_add > > >>> [ 819.770078] PM: Adding info for No Bus:BAT1 > > >>> [ 819.770235] BUG: unable to handle kernel NULL pointer dereference at (null) > > >>> [ 819.770435] IP: [] skip_spaces+0x30/0x30 > > >>> [ 819.770572] PGD 3efd90067 PUD 3eff61067 PMD 0 > > >>> [ 819.770716] Oops: 0000 [#1] SMP > > >>> [ 819.770829] Modules linked in: arc4 iwldvm mac80211 x86_pkg_temp_thermal coretemp kvm_intel joydev i915 kvm uvcvideo ghash_clmulni_intel videobuf2_vmalloc aesni_intel videobuf2_memops videobuf2_core aes_x86_64 ablk_helper cryptd videodev iwlwifi lrw rfcomm gf128mul glue_helper bnep btusb media bluetooth parport_pc hid_generic ppdev snd_hda_codec_hdmi drm_kms_helper snd_hda_codec_realtek cfg80211 drm tpm_infineon samsung_laptop snd_hda_intel usbhid snd_hda_codec hid snd_hwdep snd_pcm microcode snd_page_alloc snd_timer psmouse i2c_algo_bit lpc_ich tpm_tis video wmi mac_hid serio_raw ext2 lp parport r8169 mii > > >>> [ 819.771802] CPU: 0 PID: 2167 Comm: bash Not tainted 3.12.0+ #25 > > >>> [ 819.771876] Hardware name: SAMSUNG ELECTRONICS CO., LTD. 900X3C/900X3D/900X4C/900X4D/SAMSUNG_NP1234567890, BIOS P03AAC 07/12/2012 > > >>> [ 819.772022] task: ffff88002e6ddcc0 ti: ffff8804015ca000 task.ti: ffff8804015ca000 > > >>> [ 819.772119] RIP: 0010:[] [] skip_spaces+0x30/0x30 > > >>> [ 819.772242] RSP: 0018:ffff8804015cbc70 EFLAGS: 00010046 > > >>> [ 819.772310] RAX: 0000000000000003 RBX: ffff88040cfd6d40 RCX: 0000000000000018 > > >>> [ 819.772397] RDX: 0000000000020001 RSI: 0000000000000000 RDI: 0000000000000000 > > >>> [ 819.772484] RBP: ffff8804015cbcc0 R08: 0000000000000000 R09: ffff8803f0768d40 > > >>> [ 819.772570] R10: ffffea001033b800 R11: 0000000000000000 R12: ffffffff81c519c0 > > >>> [ 819.772656] R13: 0000000000020001 R14: 0000000000000000 R15: 0000000000020001 > > >>> [ 819.772744] FS: 00007ff98309b740(0000) GS:ffff88041f200000(0000) knlGS:0000000000000000 > > >>> [ 819.772845] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > >>> [ 819.772917] CR2: 0000000000000000 CR3: 00000003f59dc000 CR4: 00000000001407f0 > > >>> [ 819.773001] Stack: > > >>> [ 819.773030] ffffffff81114003 ffff8804015cbcb0 0000000000000000 0000000000000046 > > >>> [ 819.773146] ffff880409757a18 ffff8803f065a160 0000000000000000 0000000000020001 > > >>> [ 819.773273] 0000000000000000 0000000000000000 ffff8804015cbce8 ffffffff8143e388 > > >>> [ 819.773387] Call Trace: > > >>> [ 819.773434] [] ? ftrace_raw_event_wakeup_source+0x43/0xe0 > > >>> [ 819.773520] [] wakeup_source_report_event+0xb8/0xd0 > > >>> [ 819.773595] [] __pm_stay_awake+0x2d/0x50 > > >>> [ 819.773724] [] power_supply_changed+0x3c/0x90 > > >>> [ 819.773795] [] power_supply_register+0x18c/0x250 > > >>> [ 819.773869] [] sysfs_add_battery+0x61/0x7b > > >>> [ 819.773935] [] battery_notify+0x37/0x3f > > >>> [ 819.774001] [] notifier_call_chain+0x4c/0x70 > > >>> [ 819.774071] [] __blocking_notifier_call_chain+0x4d/0x70 > > >>> [ 819.774149] [] blocking_notifier_call_chain+0x16/0x20 > > >>> [ 819.774227] [] pm_notifier_call_chain+0x1a/0x40 > > >>> [ 819.774316] [] hibernate+0x66/0x1c0 > > >>> [ 819.774407] [] state_store+0x71/0xa0 > > >>> [ 819.774507] [] kobj_attr_store+0xf/0x20 > > >>> [ 819.774613] [] sysfs_write_file+0x128/0x1c0 > > >>> [ 819.774735] [] vfs_write+0xbd/0x1e0 > > >>> [ 819.774841] [] SyS_write+0x49/0xa0 > > >>> [ 819.774939] [] system_call_fastpath+0x16/0x1b > > >>> [ 819.775055] Code: 89 f8 48 89 e5 f6 82 c0 a6 84 81 20 74 15 0f 1f 44 00 00 48 83 c0 01 0f b6 10 f6 82 c0 a6 84 81 20 75 f0 5d c3 66 0f 1f 44 00 00 <80> 3f 00 55 48 89 e5 74 15 48 89 f8 0f 1f 40 00 48 83 c0 01 80 > > >>> [ 819.775760] RIP [] skip_spaces+0x30/0x30 > > >>> [ 819.775881] RSP > > >>> [ 819.775949] CR2: 0000000000000000 > > >>> [ 819.794175] ---[ end trace c4ef25127039952e ]--- > > >>> > > >>> Signed-off-by: Shuah Khan > > >>> --- > > >>> drivers/base/power/wakeup.c | 3 +++ > > >>> 1 file changed, 3 insertions(+) > > >>> > > >>> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c > > >>> index 2d56f41..a605f0d 100644 > > >>> --- a/drivers/base/power/wakeup.c > > >>> +++ b/drivers/base/power/wakeup.c > > >>> @@ -223,6 +223,9 @@ int device_wakeup_enable(struct device *dev) > > >>> if (!dev || !dev->power.can_wakeup) > > >>> return -EINVAL; > > >>> > > >>> + if (WARN_ON(!dev_name(dev))) > > >>> + return -EINVAL; > > >>> + > > >>> ws = wakeup_source_register(dev_name(dev)); > > >> > > >> Shouldn't wakeup_source_register() just handle a NULL for a name better? > > > > > > In fact, it does. > > > > > > The bug is in wakeup_source_activate() and that's because it passes ws->name > > > to trace_wakeup_source_activate() which then doesn't bother to check it against > > > NULL. > > > > > > So the solution here is to check ws->name before attempting to pass > > > it to trace_wakeup_source_activate() in wakeup_source_activate(). It is > > > actually valid to have a wakeup source with a NULL name and it shouldn't > > > blow up like this. > > > > > > Thanks, > > > Rafael > > > > > > > Rafael beat me to it. Yes adding the following to > > DECLARE_EVENT_CLASS(wakeup_source, should take care of the problem: > > > > > > const char *tmp_i = name ? name : "ws no name"; Well, please use something like "(no name)" here. > > > > __assign_str(name, tmp_i); > > > > should make trace_wakeup_source_activate() not blow up. I did consider > > this as one of the fixes to the oops. Would you rather see this fix > > instead of this change to device_wakeup_enable()? > > Obviously, I would. :-) > > As I said, it should be possible to register a wakeup source without a name. > > Also please find the commit that added trace_wakeup_source_activate() to > wakeup_source_activate() and add a Fixes: tag for it to the patch. Thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.