Re: [Qemu-devel] [PATCH v3 1/4] Add Error **errp for xen_host_pci_device_get()

[Eric Blake]

On 01/05/2016 07:39 PM, Cao jin wrote:
> To catch the error msg. Also modify the caller
> 
> Signed-off-by: Cao jin <address@hidden>
> ---
>  hw/xen/xen-host-pci-device.c | 106 
> +++++++++++++++++++++++++------------------
>  hw/xen/xen-host-pci-device.h |   5 +-
>  hw/xen/xen_pt.c              |  12 +++--
>  3 files changed, 71 insertions(+), 52 deletions(-)
> 
> diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
> index 7d8a023..952cae0 100644
> --- a/hw/xen/xen-host-pci-device.c
> +++ b/hw/xen/xen-host-pci-device.c
> @@ -49,7 +49,7 @@ static int xen_host_pci_sysfs_path(const XenHostPCIDevice 
> *d,
>  
>  /* This size should be enough to read the first 7 lines of a resource file */
>  #define XEN_HOST_PCI_RESOURCE_BUFFER_SIZE 400
> -static int xen_host_pci_get_resource(XenHostPCIDevice *d)
> +static void xen_host_pci_get_resource(XenHostPCIDevice *d, Error **errp)
>  {
>      int i, rc, fd;
>      char path[PATH_MAX];
> @@ -60,23 +60,24 @@ static int xen_host_pci_get_resource(XenHostPCIDevice *d)
>  
>      rc = xen_host_pci_sysfs_path(d, "resource", path, sizeof (path));
>      if (rc) {
> -        return rc;
> +        error_setg_errno(errp, errno, "snprintf err");

Are you sure that errno is relevant?  And "snprintf err" doesn't seem to
be the correct message, as there is no snprintf in the line above.

> +        return;
>      }
> +
>      fd = open(path, O_RDONLY);
>      if (fd == -1) {
> -        XEN_HOST_PCI_LOG("Error: Can't open %s: %s\n", path, 
> strerror(errno));
> -        return -errno;
> +        error_setg_errno(errp, errno, "open %s err", path);

Please use error_setg_file_open() for reporting open() failures.

> @@ -129,20 +130,20 @@ static int xen_host_pci_get_resource(XenHostPCIDevice 
> *d)
>              d->rom.bus_flags = flags & IORESOURCE_BITS;
>          }
>      }
> +
>      if (i != PCI_NUM_REGIONS) {
>          /* Invalid format or input to short */
> -        rc = -ENODEV;
> +        error_setg(errp, "Invalid format or input to short: %s", buf);

s/to/too/ (and might as well fix the same typo in the comment while at it)


> @@ -152,47 +153,52 @@ static int xen_host_pci_get_value(XenHostPCIDevice *d, 
> const char *name,
>  
>      rc = xen_host_pci_sysfs_path(d, name, path, sizeof (path));
>      if (rc) {
> -        return rc;
> +        error_setg_errno(errp, errno, "snprintf err");
> +        return;
>      }
> +
>      fd = open(path, O_RDONLY);
>      if (fd == -1) {
> -        XEN_HOST_PCI_LOG("Error: Can't open %s: %s\n", path, 
> strerror(errno));
> -        return -errno;
> +        error_setg_errno(errp, errno, "open %s err", path);

Same comments as above.

> +        return;
>      }
> +
>      do {
>          rc = read(fd, &buf, sizeof (buf) - 1);
>          if (rc < 0 && errno != EINTR) {
> -            rc = -errno;
> +            error_setg_errno(errp, errno, "read err");
>              goto out;
>          }
>      } while (rc < 0);
> +
>      buf[rc] = 0;
>      value = strtol(buf, &endptr, base);
>      if (endptr == buf || *endptr != '\n') {
> -        rc = -1;
> +        error_setg(errp, "format invalid: %s", buf);
>      } else if ((value == LONG_MIN || value == LONG_MAX) && errno == ERANGE) {
> -        rc = -errno;
> +        error_setg_errno(errp, errno, "strtol err");

This is pre-existing invalid use of strtol (the value of errno is not
guaranteed to be ERANGE on overflow; and the only correct way to safely
check errno after strtol() is to first prime it to 0 prior to calling
strtol).  Better would be to use qemu_strtol() (preferably as a separate
patch), so that you don't even have to worry about using strtol()
incorrectly.

> +static void xen_host_pci_config_open(XenHostPCIDevice *d, Error **errp)
>  {
>      char path[PATH_MAX];
>      int rc;
>  
>      rc = xen_host_pci_sysfs_path(d, "config", path, sizeof (path));

May want to delete the space before ( while touching the code in this
vicinity.

>      if (rc) {
> -        return rc;
> +        error_setg_errno(errp, errno, "snprintf err");

Another suspect message.


> +void xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
> +                            uint8_t bus, uint8_t dev, uint8_t func,
> +                            Error **errp)
>  {
>      unsigned int v;
> -    int rc = 0;
> +    Error *local_err = NULL;

These days, naming the local variable 'err' is more common than 'local_err'.

> @@ -774,11 +775,12 @@ static int xen_pt_initfn(PCIDevice *d)
>                 s->hostaddr.bus, s->hostaddr.slot, s->hostaddr.function,
>                 s->dev.devfn);
>  
> -    rc = xen_host_pci_device_get(&s->real_device,
> -                                 s->hostaddr.domain, s->hostaddr.bus,
> -                                 s->hostaddr.slot, s->hostaddr.function);
> -    if (rc) {
> -        XEN_PT_ERR(d, "Failed to \"open\" the real pci device. rc: %i\n", 
> rc);
> +    xen_host_pci_device_get(&s->real_device,
> +                            s->hostaddr.domain, s->hostaddr.bus,
> +                            s->hostaddr.slot, s->hostaddr.function,
> +                            &local_err);
> +    if (local_err) {
> +        XEN_PT_ERR(d, "Failed to \"open\" the real pci device.\n");

Leaks local_err.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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