From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id ED729F11 for ; Thu, 17 Jan 2019 03:13:58 +0100 (CET) X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Jan 2019 18:13:57 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,488,1539673200"; d="scan'208";a="110501218" Received: from yexl-server.sh.intel.com (HELO localhost) ([10.67.110.206]) by orsmga008.jf.intel.com with ESMTP; 16 Jan 2019 18:13:56 -0800 Date: Thu, 17 Jan 2019 10:13:54 +0800 From: Ye Xiaolong To: Stephen Hemminger Cc: dev@dpdk.org, Ferruh Yigit Message-ID: <20190117021354.GA47093@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190116105521.0254cdb2@shemminger-XPS-13-9360> User-Agent: Mutt/1.9.4 (2018-02-28) Subject: Re: [dpdk-dev] [PATCH v2] igb_uio: remove out-of-date comment X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: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: Thu, 17 Jan 2019 02:13:59 -0000 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 The comment for igbuio_pci_irqhandler is out of date as the code evolves, 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. Thanks, Xiaolong