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SubjectRe: [PATCH 20/23] xen-pcifront: Xen PCI frontend driver.
>>> On 12.10.10 at 17:44, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -40,6 +40,21 @@ config PCI_STUB
>
> When in doubt, say N.
>
> +config XEN_PCIDEV_FRONTEND
> + tristate "Xen PCI Frontend"
> + depends on PCI && X86 && XEN
> + select HOTPLUG
> + select PCI_XEN
> + default y
> + help
> + The PCI device frontend driver allows the kernel to import
> arbitrary
> + PCI devices from a PCI backend to support PCI driver domains.
> +
> +config XEN_PCIDEV_FE_DEBUG
> + bool
> + depends on PCI_DEBUG
> + default n

A bool without prompt, (pointlessly) defaulting to 'n', and without
getting selected anywhere has no way to get set to 'y'...

> +
> config HT_IRQ
> bool "Interrupts on hypertransport devices"
> default y
> --- /dev/null
> +++ b/drivers/pci/xen-pcifront.c
> @@ -0,0 +1,1157 @@
> +/*
> + * Xen PCI Frontend.
> + *
> + * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
> + */
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/mm.h>
> +#include <xen/xenbus.h>
> +#include <xen/events.h>
> +#include <xen/grant_table.h>
> +#include <xen/page.h>
> +#include <linux/spinlock.h>
> +#include <linux/pci.h>
> +#include <linux/msi.h>
> +#include <xen/xenbus.h>
> +#include <xen/interface/io/pciif.h>
> +#include <asm/xen/pci.h>
> +#include <linux/interrupt.h>
> +#include <asm/atomic.h>
> +#include <linux/workqueue.h>
> +#include <linux/bitops.h>
> +#include <linux/time.h>
> +
> +
> +#ifndef __init_refok
> +#define __init_refok
> +#endif

???

> +
> +#define INVALID_GRANT_REF (0)
> +#define INVALID_EVTCHN (-1)
> +
> +
> +struct pci_bus_entry {
> + struct list_head list;
> + struct pci_bus *bus;
> +};
> +
> +#define _PDEVB_op_active (0)
> +#define PDEVB_op_active (1 << (_PDEVB_op_active))
> +
> +struct pcifront_device {
> + struct xenbus_device *xdev;
> + struct list_head root_buses;
> +
> + int evtchn;
> + int gnt_ref;
> +
> + int irq;
> +
> + /* Lock this when doing any operations in sh_info */
> + spinlock_t sh_info_lock;
> + struct xen_pci_sharedinfo *sh_info;
> + struct work_struct op_work;
> + unsigned long flags;
> +
> +};
> +
> +struct pcifront_sd {
> + int domain;
> + struct pcifront_device *pdev;
> +};
> +
> +static inline struct pcifront_device *
> +pcifront_get_pdev(struct pcifront_sd *sd)
> +{
> + return sd->pdev;
> +}
> +
> +static inline void pcifront_init_sd(struct pcifront_sd *sd,
> + unsigned int domain, unsigned int bus,
> + struct pcifront_device *pdev)
> +{
> + sd->domain = domain;
> + sd->pdev = pdev;
> +}
> +
> +static inline void pcifront_setup_root_resources(struct pci_bus *bus,
> + struct pcifront_sd *sd)
> +{
> +}

???

> +
> +
> +DEFINE_SPINLOCK(pcifront_dev_lock);

static?

>...
> +void pcifront_do_aer(struct work_struct *data)

static?

>...
> +irqreturn_t pcifront_handler_aer(int irq, void *dev)

static?

>...
> +int pcifront_connect(struct pcifront_device *pdev)

static?

>...
> +void pcifront_disconnect(struct pcifront_device *pdev)

static?

>...
> +static void free_pdev(struct pcifront_device *pdev)
> +{
> + dev_dbg(&pdev->xdev->dev, "freeing pdev @ 0x%p\n", pdev);
> +
> + pcifront_free_roots(pdev);
> +
> + /*For PCIE_AER error handling job*/
> + flush_scheduled_work();

if (pdev->irq > 0)
> + unbind_from_irqhandler(pdev->irq, pdev);
> +
> + if (pdev->evtchn != INVALID_EVTCHN)
> + xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
> +
> + if (pdev->gnt_ref != INVALID_GRANT_REF)
> + gnttab_end_foreign_access(pdev->gnt_ref, 0 /* r/w page */,
> + (unsigned long)pdev->sh_info);

else
free_page((unsigned long)pdev->sh_info);

> +
> + dev_set_drvdata(&pdev->xdev->dev, NULL);
> +
> + kfree(pdev);
> +}
> +
> +static int pcifront_publish_info(struct pcifront_device *pdev)
> +{
> + int err = 0;
> + struct xenbus_transaction trans;
> +
> + err = xenbus_grant_ring(pdev->xdev, virt_to_mfn(pdev->sh_info));
> + if (err < 0)
> + goto out;
> +
> + pdev->gnt_ref = err;
> +
> + err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
> + if (err)
> + goto out;
> +
> + err = bind_evtchn_to_irqhandler(pdev->evtchn, pcifront_handler_aer,
> + 0, "pcifront", pdev);
> + if (err < 0) {
> + xenbus_free_evtchn(pdev->xdev, pdev->evtchn);

You're leaking the grant ref here. I think it's better to not do any
cleanup here, and instead call free_pdev() on error in
pcifront_xenbus_probe() (see below).

> + xenbus_dev_fatal(pdev->xdev, err, "Failed to bind evtchn to "
> + "irqhandler.\n");
> + return err;
> + }
> + pdev->irq = err;
>...
> +static int __devinit pcifront_try_connect(struct pcifront_device *pdev)
> +{
> + int err = -EFAULT;
> + int i, num_roots, len;
> + char str[64];
> + unsigned int domain, bus;
> +

The original code had a per-device lock here and in subsequent
functions. Is this being dropped due to implicit serialization through
only running in the context of the single xenbus thread?

>...
> +static int pcifront_xenbus_probe(struct xenbus_device *xdev,
> + const struct xenbus_device_id *id)
> +{
> + int err = 0;
> + struct pcifront_device *pdev = alloc_pdev(xdev);
> +
> + if (pdev == NULL) {
> + err = -ENOMEM;
> + xenbus_dev_fatal(xdev, err,
> + "Error allocating pcifront_device struct");
> + goto out;
> + }
> +
> + err = pcifront_publish_info(pdev);

if (err)
free_pdev(pdev);
> +
> +out:
> + return err;
> +}
>...

Jan


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