Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934987AbcKMToi (ORCPT ); Sun, 13 Nov 2016 14:44:38 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:60132 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934208AbcKMToh (ORCPT ); Sun, 13 Nov 2016 14:44:37 -0500 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org EC07F6120D Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=pprakash@codeaurora.org Subject: Re: [PATCH v3] mailbox: PCC: Fix lockdep warning when request PCC channel To: Hoan Tran , "Rafael J. Wysocki" , Jassi Brar References: <1477607684-5314-1-git-send-email-hotran@apm.com> Cc: linux acpi , lkml , Loc Ho , Duc Dang From: "Prakash, Prashanth" Message-ID: <4d6fd670-05d3-914d-b394-0d4cb94b247f@codeaurora.org> Date: Sun, 13 Nov 2016 12:44:33 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7310 Lines: 173 HI Hoan, On 11/9/2016 11:39 PM, Hoan Tran wrote: > Hi All, > > On Thu, Oct 27, 2016 at 3:34 PM, Hoan Tran wrote: >> This patch fixes the lockdep warning below >> >> [ 7.229767] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) >> [ 7.229776] ------------[ cut here ]------------ >> [ 7.229787] WARNING: CPU: 1 PID: 1 at linux-next/kernel/locking/lockdep.c:2876 loc >> kdep_trace_alloc+0xe0/0xf0 >> [ 7.229790] Modules linked in: >> [ 7.229793] >> [ 7.229798] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.8.0-11756-g86c5152 #46 >> ... >> [ 7.229900] Call trace: >> [ 7.229903] Exception stack(0xffff8007da837890 to 0xffff8007da8379c0) >> [ 7.229906] 7880: ffff8007da834000 0001000000000000 >> [ 7.229909] 78a0: ffff8007da837a70 ffff0000081111a0 00000000600000c5 000000000000003d >> [ 7.229912] 78c0: 9374bc6a7f3c7832 0000000000381878 ffff000009db7ab8 000000000000002f >> [ 7.229915] 78e0: ffff00000811aabc ffff000008be2548 ffff8007da837990 ffff00000811adf8 >> [ 7.229918] 7900: ffff8007da834000 00000000024080c0 00000000000000c0 ffff000009021000 >> [ 7.229921] 7920: 0000000000000000 0000000000000000 ffff000008c8f7c8 ffff8007da579810 >> [ 7.229923] 7940: 000000000000002f ffff8007da858000 0000000000000000 0000000000000001 >> [ 7.229926] 7960: 0000000000000001 0000000000000000 ffff00000811a468 0000000000000002 >> [ 7.229929] 7980: 656c62617369645f 0000000000038187 00000000000000ee ffff8007da837850 >> [ 7.229932] 79a0: ffff000009db50c0 ffff000009db569d 0000000000000006 ffff000089db568f >> [ 7.229936] [] lockdep_trace_alloc+0xe0/0xf0 >> [ 7.229940] [] __kmalloc_track_caller+0x50/0x250 >> [ 7.229945] [] devres_alloc_node+0x28/0x60 >> [ 7.229949] [] devm_request_threaded_irq+0x50/0xe0 >> [ 7.229955] [] pcc_mbox_request_channel+0x110/0x170 >> [ 7.229960] [] acpi_cppc_processor_probe+0x264/0x414 >> [ 7.229963] [] __acpi_processor_start+0x28/0xa0 >> [ 7.229966] [] acpi_processor_start+0x44/0x54 >> [ 7.229970] [] driver_probe_device+0x1fc/0x2b0 >> [ 7.229974] [] __driver_attach+0xb4/0xc0 >> [ 7.229977] [] bus_for_each_dev+0x5c/0xa0 >> [ 7.229980] [] driver_attach+0x20/0x30 >> [ 7.229983] [] bus_add_driver+0x110/0x230 >> [ 7.229987] [] driver_register+0x60/0x100 >> [ 7.229991] [] acpi_processor_driver_init+0x2c/0xb0 >> [ 7.229996] [] do_one_initcall+0x38/0x130 >> [ 7.230000] [] kernel_init_freeable+0x210/0x2b4 >> [ 7.230004] [] kernel_init+0x10/0x110 >> [ 7.230007] [] ret_from_fork+0x10/0x50 >> >> It's because the spinlock inside pcc_mbox_request_channel() is >> kept too long. This patch releases spinlock before request_irq() >> and free_irq() to fix this issue as spinlock is only needed to >> protect the channel data. >> >> Signed-off-by: Hoan Tran >> --- >> v3 >> * Free mailbox irq before reset the channel data >> * Free channel if it fails to request the mailbox irq >> >> v2 >> * Release spinlock before request_irq() and free_irq() instead of >> using mutex >> >> >> drivers/mailbox/pcc.c | 70 +++++++++++++++++++++++++-------------------------- >> 1 file changed, 35 insertions(+), 35 deletions(-) >> >> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c >> index 08c87fa..4b2f061 100644 >> --- a/drivers/mailbox/pcc.c >> +++ b/drivers/mailbox/pcc.c >> @@ -224,6 +224,38 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p) >> } >> >> /** >> + * pcc_mbox_free_channel - Clients call this to free their Channel. >> + * >> + * @chan: Pointer to the mailbox channel as returned by >> + * pcc_mbox_request_channel() >> + */ >> +void pcc_mbox_free_channel(struct mbox_chan *chan) >> +{ >> + u32 id = chan - pcc_mbox_channels; >> + unsigned long flags; >> + >> + if (!chan || !chan->cl) >> + return; >> + >> + if (id >= pcc_mbox_ctrl.num_chans) { >> + pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n"); >> + return; >> + } >> + >> + if (pcc_doorbell_irq[id] > 0) >> + devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan); >> + >> + spin_lock_irqsave(&chan->lock, flags); >> + chan->cl = NULL; >> + chan->active_req = NULL; >> + if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) >> + chan->txdone_method = TXDONE_BY_POLL; >> + >> + spin_unlock_irqrestore(&chan->lock, flags); >> +} >> +EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); >> + >> +/** >> * pcc_mbox_request_channel - PCC clients call this function to >> * request a pointer to their PCC subspace, from which they >> * can get the details of communicating with the remote. >> @@ -267,6 +299,8 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, >> if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) >> chan->txdone_method |= TXDONE_BY_ACK; >> >> + spin_unlock_irqrestore(&chan->lock, flags); >> + >> if (pcc_doorbell_irq[subspace_id] > 0) { >> int rc; >> >> @@ -275,50 +309,16 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, >> if (unlikely(rc)) { >> dev_err(dev, "failed to register PCC interrupt %d\n", >> pcc_doorbell_irq[subspace_id]); >> + pcc_mbox_free_channel(chan); >> chan = ERR_PTR(rc); >> } >> } >> >> - spin_unlock_irqrestore(&chan->lock, flags); >> - >> return chan; >> } >> EXPORT_SYMBOL_GPL(pcc_mbox_request_channel); >> >> /** >> - * pcc_mbox_free_channel - Clients call this to free their Channel. >> - * >> - * @chan: Pointer to the mailbox channel as returned by >> - * pcc_mbox_request_channel() >> - */ >> -void pcc_mbox_free_channel(struct mbox_chan *chan) >> -{ >> - u32 id = chan - pcc_mbox_channels; >> - unsigned long flags; >> - >> - if (!chan || !chan->cl) >> - return; >> - >> - if (id >= pcc_mbox_ctrl.num_chans) { >> - pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n"); >> - return; >> - } >> - >> - spin_lock_irqsave(&chan->lock, flags); >> - chan->cl = NULL; >> - chan->active_req = NULL; >> - if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) >> - chan->txdone_method = TXDONE_BY_POLL; >> - >> - if (pcc_doorbell_irq[id] > 0) >> - devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan); >> - >> - spin_unlock_irqrestore(&chan->lock, flags); >> -} >> -EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); Instead of completely relocating an exported function within the file, I think we can just include the "pcc.h" header, which makes it a little easier to review. Otherwise, the control flow looks ok now. -- Thanks, Prashanth