From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by dpdk.org (Postfix) with ESMTP id D1D28239 for ; Tue, 22 Jan 2019 02:52:42 +0100 (CET) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Jan 2019 17:52:41 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,504,1539673200"; d="scan'208";a="127790459" Received: from yexl-server.sh.intel.com (HELO localhost) ([10.67.110.206]) by orsmga002.jf.intel.com with ESMTP; 21 Jan 2019 17:52:40 -0800 Date: Tue, 22 Jan 2019 09:52:19 +0800 From: Ye Xiaolong To: Stephen Hemminger Cc: dev@dpdk.org, Ferruh Yigit Message-ID: <20190122015219.GA88690@intel.com> References: <20190115154626.34516-1-xiaolong.ye@intel.com> <20190116003452.37403-1-xiaolong.ye@intel.com> <20190115173822.25a4a979@shemminger-XPS-13-9360> <20190116074836.GB39571@intel.com> <20190116105521.0254cdb2@shemminger-XPS-13-9360> <20190117021354.GA47093@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190117021354.GA47093@intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Subject: Re: [dpdk-dev] [PATCH v2] igb_uio: remove out-of-date comment X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Jan 2019 01:52:43 -0000 Hi, Stephen On 01/17, Ye Xiaolong wrote: >On 01/16, Stephen Hemminger wrote: >>On Wed, 16 Jan 2019 15:48:36 +0800 >>Ye Xiaolong wrote: >> >>> Hi, Stephen >>> >>> On 01/15, Stephen Hemminger wrote: >>> >On Wed, 16 Jan 2019 08:34:52 +0800 >>> >Xiaolong Ye wrote: >>> > >>> >> The comment for igbuio_pci_irqhandler is out of date as the code evolves, >>> >> remove it to avoid misleading. >>> >> >>> >> Signed-off-by: Xiaolong Ye >>> >> --- >>> >> kernel/linux/igb_uio/igb_uio.c | 4 ---- >>> >> 1 file changed, 4 deletions(-) >>> >> >>> >> diff --git a/kernel/linux/igb_uio/igb_uio.c b/kernel/linux/igb_uio/igb_uio.c >>> >> index 3cf394bdf..d6ac51e79 100644 >>> >> --- a/kernel/linux/igb_uio/igb_uio.c >>> >> +++ b/kernel/linux/igb_uio/igb_uio.c >>> >> @@ -185,10 +185,6 @@ igbuio_pci_irqcontrol(struct uio_info *info, s32 irq_state) >>> >> return 0; >>> >> } >>> >> >>> >> -/** >>> >> - * This is interrupt handler which will check if the interrupt is for the right device. >>> >> - * If yes, disable it here and will be enable later. >>> >> - */ >>> >> static irqreturn_t >>> >> igbuio_pci_irqhandler(int irq, void *dev_id) >>> >> { >>> > >>> >The comment is partially correct; if you look at the legacy case. >>> > >>> >Maybe better to move the comment to pci_check_and_mask_intx in compat.h? >>> >I see there is another incorrect comment there. >>> > >>> >>> As I tried to understand pci_check_and_mask_intx behavior, I noticed that it >>> was introduced by commit 399a3f0d ("igb_uio: fix IRQ mode handling"), and it >>> was derived from igbuio_set_interrupt_mask, however there were two parameters >>> in igbuio_set_interrupt_mask as below: >>> >>> static int >>> igbuio_set_interrupt_mask(struct rte_uio_pci_dev *udev, int32_t state) >>> >>> while the pci_check_and_mask_intx only has 1 parameter, >>> >>> static bool pci_check_and_mask_intx(struct pci_dev *pdev) >>> >>> but in its function body it still use the "state" accorrding to commit 399a3f0d >>> >>> +static bool pci_check_and_mask_intx(struct pci_dev *pdev) >>> { >>> - /* Some function names changes between 3.2.0 and 3.3.0... */ >>> -#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 3, 0) >>> - pci_unblock_user_cfg_access(pdev); >>> -#else >>> - pci_cfg_access_unlock(pdev); >>> -#endif >>> + bool pending; >>> + uint32_t status; >>> + >>> + pci_block_user_cfg_access(dev); >>> + pci_read_config_dword(pdev, PCI_COMMAND, &status); >>> + >>> + /* interrupt is not ours, goes to out */ >>> + pending = (((status >> 16) & PCI_STATUS_INTERRUPT) != 0); >>> + if (pending) { >>> + uint16_t old, new; >>> + >>> + old = status; >>> + if (state != 0) <=========================== state still in use >>> + new = old & (~PCI_COMMAND_INTX_DISABLE); >>> + else >>> + new = old | PCI_COMMAND_INTX_DISABLE; >>> + >>> + if (old != new) >>> + pci_write_config_word(pdev, PCI_COMMAND, new); >>> + } >>> + pci_unblock_user_cfg_access(dev); >>> + >>> + return pending; >>> >>> and later this was fixed as a typo in commit 5b2f8137 ("igb_uio: fix typos for >>> kernel older than 3.3") which seems not correct. >>> >>> old = status; >>> - if (state != 0) >>> + if (status != 0) >>> >>> I feel like that pci_check_and_mask_intx still needs two parameters from code >>> point of view, please correct me if I was wrong or miss anything, or you think >>> it's sensible, I'll cook a patch for it. >>> >>> Thanks, >>> Xiaolong >> >>This code is copy of upstream kernel function, you should look at that. > >Thanks, just checked the kernel version of pci_check_and_mask_intx, and it is a >wrap of pci_check_and_set_intx_mask(pdev, true). > > > bool pci_check_and_mask_intx(struct pci_dev *dev) > { > return pci_check_and_set_intx_mask(dev, true); > } > > > static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask) > { > struct pci_bus *bus = dev->bus; > ... > origcmd = cmd_status_dword; > newcmd = origcmd & ~PCI_COMMAND_INTX_DISABLE; > if (mask) > newcmd |= PCI_COMMAND_INTX_DISABLE; > if (newcmd != origcmd) > bus->ops->write(bus, dev->devfn, PCI_COMMAND, 2, newcmd); > > done: > raw_spin_unlock_irqrestore(&pci_lock, flags); > > return mask_updated; > } > >if mask is set to ture, PCI_COMMAND_INTX_DISABLE will be set in newcmd. > >And current dpdk version doesn't align with it: > > static bool pci_check_and_mask_intx(struct pci_dev *pdev) > { > bool pending; > uint32_t status; > > pci_block_user_cfg_access(pdev); > pci_read_config_dword(pdev, PCI_COMMAND, &status); > > /* interrupt is not ours, goes to out */ > pending = (((status >> 16) & PCI_STATUS_INTERRUPT) != 0); > if (pending) { > uint16_t old, new; > > old = status; > if (status != 0) > new = old & (~PCI_COMMAND_INTX_DISABLE); > else > new = old | PCI_COMMAND_INTX_DISABLE; > > if (old != new) > pci_write_config_word(pdev, PCI_COMMAND, new); > } > pci_unblock_user_cfg_access(pdev); > > return pending; > } > >In this code, if the interrupt is triggered by this device, both pending and >status will not be 0, so the PCI_COMMAND_INTX_DISABLE will be cleared for new. > >To align the behavior with upstream kernel, we may need change like: > >diff --git a/kernel/linux/igb_uio/compat.h b/kernel/linux/igb_uio/compat.h >index 8dbb896ae..a78c97f91 100644 >--- a/kernel/linux/igb_uio/compat.h >+++ b/kernel/linux/igb_uio/compat.h >@@ -107,10 +107,7 @@ static bool pci_check_and_mask_intx(struct pci_dev *pdev) > uint16_t old, new; > > old = status; >- if (status != 0) >- new = old & (~PCI_COMMAND_INTX_DISABLE); >- else >- new = old | PCI_COMMAND_INTX_DISABLE; >+ new = old | PCI_COMMAND_INTX_DISABLE; > > if (old != new) > pci_write_config_word(pdev, PCI_COMMAND, new); > > >Please correct me if I was wrong. Does my above fix make any sense? Thanks, Xiaolong > >Thanks, >Xiaolong