From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754654AbYIHRSv (ORCPT ); Mon, 8 Sep 2008 13:18:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752439AbYIHRSm (ORCPT ); Mon, 8 Sep 2008 13:18:42 -0400 Received: from mga11.intel.com ([192.55.52.93]:9141 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752080AbYIHRSl (ORCPT ); Mon, 8 Sep 2008 13:18:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.32,359,1217833200"; d="scan'208";a="377971253" Date: Mon, 8 Sep 2008 10:18:40 -0700 From: Venki Pallipadi To: Ingo Molnar Cc: "Pallipadi, Venkatesh" , "tglx@linutronix.de" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "Li, Shaohua" , Yinghai Lu Subject: Re: [RFC 0/4] Using HPET in MSI mode and setting up per CPU HPET timers Message-ID: <20080908171840.GA31009@linux-os.sc.intel.com> References: <20080906010214.229910000@intel.com> <20080906124234.GG30964@elte.hu> <20080906130353.GA30340@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080906130353.GA30340@elte.hu> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 06, 2008 at 06:03:53AM -0700, Ingo Molnar wrote: > > it crashes two testsystems, the fault on a NULL pointer in hpet init, > with: > > initcall print_all_ICs+0x0/0x520 returned 0 after 26 msecs > calling hpet_late_init+0x0/0x1c0 > BUG: unable to handle kernel NULL pointer dereference at 000000000000008c > IP: [] hpet_late_init+0xfe/0x1c0 > PGD 0 > Oops: 0000 [1] SMP > CPU 0 > Modules linked in: > Pid: 1, comm: swapper Not tainted 2.6.27-rc5 #29725 > RIP: 0010:[] [] hpet_late_init+0xfe/0x1c0 > RSP: 0018:ffff88003fa07dd0 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000 > RDX: ffffc20000000160 RSI: 0000000000000000 RDI: 0000000000000003 > RBP: ffff88003fa07e90 R08: 0000000000000000 R09: ffff88003fa07dd0 > R10: 0000000000000001 R11: 0000000000000000 R12: ffff88003fa07dd0 > R13: 0000000000000002 R14: ffffc20000000000 R15: 000000006f57e511 > FS: 0000000000000000(0000) GS:ffffffff80cf6a80(0000) knlGS:0000000000000000 > CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b > CR2: 000000000000008c CR3: 0000000000201000 CR4: 00000000000006e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process swapper (pid: 1, threadinfo ffff88003fa06000, task ffff88003fa08000) > Stack: 00000000fed00000 ffffc20000000000 0000000100000003 0000000800000002 > 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > Call Trace: > [] ? hpet_late_init+0x0/0x1c0 > [] do_one_initcall+0x45/0x190 > [] ? register_irq_proc+0x19/0xe0 > [] ? early_idt_handler+0x0/0x73 > [] kernel_init+0x14c/0x1b0 > [] ? trace_hardirqs_on_thunk+0x3a/0x3f > [] child_rip+0xa/0x11 > [] ? restore_args+0x0/0x30 > [] ? kernel_init+0x0/0x1b0 > [] ? child_rip+0x0/0x11 > Code: 20 48 83 c1 01 48 39 f1 75 e3 44 89 e8 4c 8b 05 29 29 22 00 31 f6 48 8d 78 01 66 66 90 89 f0 48 8d 04 80 48 c1 e0 05 4a 8d 0c 00 81 8c 00 00 00 08 74 26 8b 81 80 00 00 00 8b 91 88 00 00 00 > RIP [] hpet_late_init+0xfe/0x1c0 > RSP > CR2: 000000000000008c > Kernel panic - not syncing: Fatal exception There was one code path, with CONFIG_PCI_MSI disabled, where we were accessing hpet_devs without initialization. That resulted in the above crash. The change below adds a check for hpet_devs. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Shaohua Li --- arch/x86/kernel/hpet.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) Index: tip/arch/x86/kernel/hpet.c =================================================================== --- tip.orig/arch/x86/kernel/hpet.c 2008-09-08 09:20:00.000000000 -0700 +++ tip/arch/x86/kernel/hpet.c 2008-09-08 09:44:23.000000000 -0700 @@ -124,6 +124,24 @@ EXPORT_SYMBOL_GPL(is_hpet_enabled); * timer 0 and timer 1 in case of RTC emulation. */ #ifdef CONFIG_HPET +static void hpet_reserve_msi_timers(struct hpet_data *hd) +{ + int i; + + if (!hpet_devs) + return; + + for (i = 0; i < hpet_num_timers; i++) { + struct hpet_dev *hdev = &hpet_devs[i]; + + if (!(hdev->flags & HPET_DEV_VALID)) + continue; + + hd->hd_irq[hdev->num] = hdev->irq; + hpet_reserve_timer(hd, hdev->num); + } +} + static void hpet_reserve_platform_timers(unsigned long id) { struct hpet __iomem *hpet = hpet_virt_address; @@ -156,15 +174,7 @@ static void hpet_reserve_platform_timers Tn_INT_ROUTE_CNF_SHIFT; } - for (i = 0; i < nrtimers; i++) { - struct hpet_dev *hdev = &hpet_devs[i]; - - if (!(hdev->flags & HPET_DEV_VALID)) - continue; - - hd.hd_irq[hdev->num] = hdev->irq; - hpet_reserve_timer(&hd, hdev->num); - } + hpet_reserve_msi_timers(&hd); hpet_alloc(&hd);