From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH v8 04/14] eal/pci: Consolidate pci address comparison APIs Date: Wed, 18 Feb 2015 02:02:23 +0100 Message-ID: <1684102.trQSmodf0H@xps13> References: <1423470639-15744-2-git-send-email-mukawa@igel.co.jp> <4367974.mVXCMbsChG@xps13> <54E2DC61.9010804@igel.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev-VfR2kkLFssw@public.gmane.org To: Tetsuya Mukawa Return-path: In-Reply-To: <54E2DC61.9010804-AlSX/UN32fvPDbFq/vQRIQ@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 2015-02-17 15:14, Tetsuya Mukawa: > On 2015/02/17 9:44, Thomas Monjalon wrote: > > 2015-02-16 13:14, Tetsuya Mukawa: > >> @@ -356,13 +342,24 @@ pci_scan_one(int dev_pci_fd, struct pci_conf *conf) > >> } > >> else { > >> struct rte_pci_device *dev2 = NULL; > >> + int ret; > >> > >> TAILQ_FOREACH(dev2, &pci_device_list, next) { > >> - if (pci_addr_comparison(&dev->addr, &dev2->addr)) > >> + ret = eal_compare_pci_addr(&dev->addr, &dev2->addr); > >> + if (ret > 0) > >> continue; > >> - else { > >> + else if (ret < 0) { > >> TAILQ_INSERT_BEFORE(dev2, dev, next); > >> return 0; > >> + } else { /* already registered */ > >> + /* update pt_driver */ > >> + dev2->pt_driver = dev->pt_driver; > >> + dev2->max_vfs = dev->max_vfs; > >> + memmove(dev2->mem_resource, > >> + dev->mem_resource, > >> + sizeof(dev->mem_resource)); > >> + free(dev); > >> + return 0; > > Could you comment this "else part" please? > > PCI device list is allocated when rte_eal_init() is called. At the time, > to fill pci device information, sysfs value is used. > If sysfs values written by kernel device driver will not be changed by > igb_uio, vfio or pci_uio_genereic, above code isn't needed. > But actually above values are changed or added by them. > > Here is a step to cause issue. > 1. Boot linux. > 2. Start DPDK application without any physical NIC ports. > - Here, some sysfs values are read, and store to pci device list. > 3. igb_uio starts managing a port. > - Here, some sysfs values are changed. > 4. Add a NIC port to DPDK application using hotplug functions. > - Here, we need to replace some values. I think that you are showing that something is wrongly designed in these EAL structures. I suggest to try cleaning this mess instead of workarounding. [...] > >> - if (memcmp(&uio_res->pci_addr, &dev->addr, sizeof(dev->addr))) > >> + if (eal_compare_pci_addr(&uio_res->pci_addr, &dev->addr)) > > Why memcmp is not sufficient to compare PCI addresses? > > The only exception I see is endianness for natural sorting. > > Here is the definition. > > struct rte_pci_addr { > uint16_t domain; /**< Device domain */ > uint8_t bus; /**< Device bus */ > uint8_t devid; /**< Device ID */ > uint8_t function; /**< Device function. */ > }; > > But, sizeof(struct rte_pci_addr) will be 6. > If rte_pci_addr is allocated in a function without bzero, last 1 byte > may have some value. > As a result, memcmp may not work. To avoid such a case, I checked like > above. OK thanks. That's the kind of information which is valuable in a commit log.