Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933380AbbHZUg2 (ORCPT ); Wed, 26 Aug 2015 16:36:28 -0400 Received: from mail-la0-f48.google.com ([209.85.215.48]:36712 "EHLO mail-la0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752695AbbHZUg0 convert rfc822-to-8bit (ORCPT ); Wed, 26 Aug 2015 16:36:26 -0400 MIME-Version: 1.0 In-Reply-To: <20150826202429.GV14625@saruman.tx.rr.com> References: <20150825195830.GH27534@saruman.tx.rr.com> <20150826193820.GT14625@saruman.tx.rr.com> <20150826200300.GU14625@saruman.tx.rr.com> <20150826202429.GV14625@saruman.tx.rr.com> Date: Wed, 26 Aug 2015 17:36:24 -0300 Message-ID: Subject: Re: CONFIG_DEBUG_SHIRQ and PM From: Ezequiel Garcia To: Felipe Balbi Cc: Ingo Molnar , Tony Lindgren , Linux OMAP Mailing List , Linux Kernel Mailing List , Linux ARM Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2335 Lines: 67 On 26 August 2015 at 17:24, Felipe Balbi wrote: [..] >> >> static irqreturn_t tw68_irq(int irq, void *dev_id) >> { >> struct tw68_dev *dev = dev_id; >> u32 status, orig; >> int loop; >> >> status = orig = tw_readl(TW68_INTSTAT) & dev->pci_irqmask; > > Now try to read that register when your clock is gated. That's the > problem I'm talking about. Everything about the handler is functioning > correctly; however clocks are gated in ->remove() and free_irq() is > only called *AFTER* ->remove() has returned. > Yeah, it's pretty clear you are talking about clocks here. That's why I said "read won't stall" in the next paragraph. >> [etc] >> } >> >> The IRQ handler accesses the device struct and then >> reads through PCI. So if you use devm_request_irq >> you need to make sure the device struct is still allocated >> after remove(), and the PCI read won't stall or crash. > > dude, that's not the problem I'm talking about. I still have my > private_data around, what I don't have is: > > _ _ > __ _ ___| | ___ ___| | __ > / _` | / __| |/ _ \ / __| |/ / > | (_| | | (__| | (_) | (__| < > \__,_| \___|_|\___/ \___|_|\_\ > > Yes, *you* may have your private data around and have a clock gated, others (the tw68 for instance) may have its region released and unmapped. And yet others may have $whatever resource released in the remove() and assume it's available in the IRQ handler. I honestly can't think why using request_irq / free_irq to solve this is a workaround. >> Interestingly, tw68 uses devm_request_irq with IRQF_SHARED :-) >> >> Still, I don't think that's a good idea, since it relies on >> the IRQ being freed *before* the device struct. > > that's not an issue at all. If you're using devm_request_irq() you're > likely using devm_kzalloc() for the device struct anyway. Also, you > called devm_kzalloc() before devm_request_irq() so IRQ *will* be freed > before your private data; there's nothing wrong there. > -- Ezequiel García, VanguardiaSur www.vanguardiasur.com.ar -- 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/