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Thu, 24 Jun 2021 22:40:47 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1lwY1b-00GbQ7-0w; Thu, 24 Jun 2021 22:40:44 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 45373613A9; Thu, 24 Jun 2021 22:40:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624574442; bh=2RVF0pPWJN9bsOvwEQ1wuKz8hUlipUgiYt0DkqZHZtU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=C07/XAF2fa67lKOB++qXyN0IRjAQX8HJ2L0BsJLlxgNNyjMCsl3m0tSFsLFA5xvqs RuJA/oxtWcJjtIhCFOGLQ0blYbayFGWQ5i0aotk9lcH/REAfA35SSMGLuGNwDYgkHU L0vY+sXoGTmF22zybs787DZkfceg+CGDn/Z4jQe2NjdWipqh0uaOHQzDcCTwmYXtiZ tOXfqBi7Sk/rL2iEDA+IVSOY7dzCq7RtxERD8QvQHfiaoF3XwlzucUapiVpKCGqc0G nS1JnsB7pu9yK+lEoi/5OS/OwRCuxUSc51hLyCBnXzi4JKdZjWPRoPV9btzF2rYi1e hxt46bcoGnE3g== Date: Thu, 24 Jun 2021 17:40:40 -0500 From: Bjorn Helgaas To: Javier Martinez Canillas Cc: linux-kernel@vger.kernel.org, Peter Robinson , Shawn Lin , Bjorn Helgaas , Heiko Stuebner , Lorenzo Pieralisi , Rob Herring , linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-rockchip@lists.infradead.org, Michal Simek , Ley Foon Tan , rfi@lists.rocketboards.org, Jingoo Han , Thierry Reding , Jonathan Hunter , linux-tegra@vger.kernel.org Subject: Re: [PATCH v2] PCI: rockchip: Avoid accessing PCIe registers with clocks gated Message-ID: <20210624224040.GA3567297@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210608080409.1729276-1-javierm@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210624_154043_168624_F20CF6B5 X-CRM114-Status: GOOD ( 38.32 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org [+cc Michal, Ley Foon, Jingoo, Thierry, Jonathan] On Tue, Jun 08, 2021 at 10:04:09AM +0200, Javier Martinez Canillas wrote: > IRQ handlers that are registered for shared interrupts can be called at > any time after have been registered using the request_irq() function. > > It's up to drivers to ensure that's always safe for these to be called. > > Both the "pcie-sys" and "pcie-client" interrupts are shared, but since > their handlers are registered very early in the probe function, an error > later can lead to these handlers being executed before all the required > resources have been properly setup. > > For example, the rockchip_pcie_read() function used by these IRQ handlers > expects that some PCIe clocks will already be enabled, otherwise trying > to access the PCIe registers causes the read to hang and never return. > > The CONFIG_DEBUG_SHIRQ option tests if drivers are able to cope with their > shared interrupt handlers being called, by generating a spurious interrupt > just before a shared interrupt handler is unregistered. > > But this means that if the option is enabled, any error in the probe path > of this driver could lead to one of the IRQ handlers to be executed. I'm not an IRQ expert, but I think this is an issue regardless of CONFIG_DEBUG_SHIRQ, isn't it? Anything used by an IRQ handler should be initialized before the handler is registered. CONFIG_DEBUG_SHIRQ is just a way to help find latent problems. > In a rockpro64 board, the following sequence of events happens: > > 1) "pcie-sys" IRQ is requested and its handler registered. > 2) "pcie-client" IRQ is requested and its handler registered. > 3) probe later fails due readl_poll_timeout() returning a timeout. > 4) the "pcie-sys" IRQ is unregistered. > 5) CONFIG_DEBUG_SHIRQ triggers a spurious interrupt. > 6) "pcie-client" IRQ handler is called for this spurious interrupt. > 7) IRQ handler tries to read PCIE_CLIENT_INT_STATUS with clocks gated. > 8) the machine hangs because rockchip_pcie_read() call never returns. > > To avoid cases like this, the handlers don't have to be registered until > very late in the probe function, once all the resources have been setup. > > So let's just move all the IRQ init before the pci_host_probe() call, that > will prevent issues like this and seems to be the correct thing to do too. Previously we registered rockchip_pcie_subsys_irq_handler() and rockchip_pcie_client_irq_handler() before the PCIe clocks were enabled. That's a problem because they depend on those clocks being enabled, and your patch fixes that. rockchip_pcie_legacy_int_handler() depends on rockchip->irq_domain, which isn't initialized until rockchip_pcie_init_irq_domain(). Previously we registered rockchip_pcie_legacy_int_handler() as the handler for the "legacy" IRQ before rockchip_pcie_init_irq_domain(). I think you patch *also* fixes that problem, right? I think this is also an issue with the following other drivers. They all set the handler to something that uses an IRQ domain before they actually initialize the domain: # nwl -------------------------------------------------------------- nwl_pcie_probe nwl_pcie_parse_dt pcie->irq_intx = platform_get_irq_byname(pdev, "intx") irq_set_chained_handler_and_data(pcie->irq_intx, nwl_pcie_leg_handler) nwl_pcie_bridge_init devm_request_irq nwl_pcie_init_irq_domain pcie->legacy_irq_domain = irq_domain_add_linear() nwl_pcie_leg_handler irq_find_mapping(pcie->legacy_irq_domain) # altera -------------------------------------------------------------- altera_pcie_probe altera_pcie_parse_dt irq_set_chained_handler_and_data(altera_pcie_isr) altera_pcie_init_irq_domain pcie->irq_domain = irq_domain_add_linear() altera_pcie_isr irq_find_mapping(pcie->irq_domain) # ks -------------------------------------------------------------- ks_pcie_config_legacy_irq irq_set_chained_handler_and_data(ks_pcie_legacy_irq_handler) ks_pcie->legacy_irq_domain = irq_domain_add_linear() ks_pcie_legacy_irq_handler ks_pcie_handle_legacy_irqirq_linear_revmap(ks_pcie->legacy_irq_domain) # tegra -------------------------------------------------------------- tegra_pcie_msi_setup if (IS_ENABLED(CONFIG_PCI_MSI)) { tegra_allocate_domains parent = irq_domain_create_linear() msi->domain = pci_msi_create_irq_domain(parent) } irq_set_chained_handler_and_data(tegra_pcie_msi_irq) tegra_pcie_msi_irq irq_find_mapping(msi->domain->parent) Tegra is a little wierd because the IS_ENABLED(CONFIG_PCI_MSI) only covers the IRQ domain alloc; it doesn't cover setting the handler. So if CONFIG_PCI_MSI is not set, we don't alloc the IRQ domain, but we still set a handler that *uses* the IRQ domain. That seems somewhat broken. > Reported-by: Peter Robinson > Signed-off-by: Javier Martinez Canillas > Acked-by: Shawn Lin > --- > > Changes in v2: > - Add missing word in the commit message. > - Include Shawn Lin's Acked-by tag. > > drivers/pci/controller/pcie-rockchip-host.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c > index f1d08a1b159..78d04ac29cd 100644 > --- a/drivers/pci/controller/pcie-rockchip-host.c > +++ b/drivers/pci/controller/pcie-rockchip-host.c > @@ -592,10 +592,6 @@ static int rockchip_pcie_parse_host_dt(struct rockchip_pcie *rockchip) > if (err) > return err; > > - err = rockchip_pcie_setup_irq(rockchip); > - if (err) > - return err; > - > rockchip->vpcie12v = devm_regulator_get_optional(dev, "vpcie12v"); > if (IS_ERR(rockchip->vpcie12v)) { > if (PTR_ERR(rockchip->vpcie12v) != -ENODEV) > @@ -973,8 +969,6 @@ static int rockchip_pcie_probe(struct platform_device *pdev) > if (err) > goto err_vpcie; > > - rockchip_pcie_enable_interrupts(rockchip); > - > err = rockchip_pcie_init_irq_domain(rockchip); > if (err < 0) > goto err_deinit_port; > @@ -992,6 +986,12 @@ static int rockchip_pcie_probe(struct platform_device *pdev) > bridge->sysdata = rockchip; > bridge->ops = &rockchip_pcie_ops; > > + err = rockchip_pcie_setup_irq(rockchip); > + if (err) > + goto err_remove_irq_domain; > + > + rockchip_pcie_enable_interrupts(rockchip); > + > err = pci_host_probe(bridge); > if (err < 0) > goto err_remove_irq_domain; > -- > 2.31.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel