Re: [Xen-devel] [PATCH] xen-pciback: support wild cards in slot specifications

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Sep 18, 2012 at 12:29:03PM +0100, Jan Beulich wrote:
> Particularly for hiding sets of SR-IOV devices, specifying them all
> individually is rather cumbersome. Therefore, allow function and slot
> numbers to be replaced by a wildcard character ('*').
> 
> Unfortunately this gets complicated by the in-kernel sscanf()
> implementation not being really standard conformant - matching of
> plain text tails cannot be checked by the caller (a patch to overcome
> this will be sent shortly, and a follow-up patch for simplifying the
> code is planned to be sent when that fixed went upstream).

applied for 3.7
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> ---
>  drivers/xen/xen-pciback/pci_stub.c |   89 
> ++++++++++++++++++++++++++++++++++---
>  1 file changed, 82 insertions(+), 7 deletions(-)
> 
> --- 3.6-rc6/drivers/xen/xen-pciback/pci_stub.c
> +++ 3.6-rc6-xen-pciback-wildcard/drivers/xen/xen-pciback/pci_stub.c
> @@ -897,17 +897,41 @@ static inline int str_to_slot(const char
>                             int *slot, int *func)
>  {
>       int err;
> +     char wc = '*';
>  
>       err = sscanf(buf, " %x:%x:%x.%x", domain, bus, slot, func);
> -     if (err == 4)
> +     switch (err) {
> +     case 3:
> +             *func = -1;
> +             err = sscanf(buf, " %x:%x:%x.%c", domain, bus, slot, &wc);
> +             break;
> +     case 2:
> +             *slot = *func = -1;
> +             err = sscanf(buf, " %x:%x:*.%c", domain, bus, &wc);
> +             if (err >= 2)
> +                     ++err;
> +             break;
> +     }
> +     if (err == 4 && wc == '*')
>               return 0;
>       else if (err < 0)
>               return -EINVAL;
>  
>       /* try again without domain */
>       *domain = 0;
> +     wc = '*';
>       err = sscanf(buf, " %x:%x.%x", bus, slot, func);
> -     if (err == 3)
> +     switch (err) {
> +     case 2:
> +             *func = -1;
> +             err = sscanf(buf, " %x:%x.%c", bus, slot, &wc);
> +             break;
> +     case 1:
> +             *slot = *func = -1;
> +             err = sscanf(buf, " %x:*.%c", bus, &wc) + 1;
> +             break;
> +     }
> +     if (err == 3 && wc == '*')
>               return 0;
>  
>       return -EINVAL;
> @@ -930,6 +954,19 @@ static int pcistub_device_id_add(int dom
>  {
>       struct pcistub_device_id *pci_dev_id;
>       unsigned long flags;
> +     int rc = 0;
> +
> +     if (slot < 0) {
> +             for (slot = 0; !rc && slot < 32; ++slot)
> +                     rc = pcistub_device_id_add(domain, bus, slot, func);
> +             return rc;
> +     }
> +
> +     if (func < 0) {
> +             for (func = 0; !rc && func < 8; ++func)
> +                     rc = pcistub_device_id_add(domain, bus, slot, func);
> +             return rc;
> +     }
>  
>       pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_KERNEL);
>       if (!pci_dev_id)
> @@ -952,15 +989,15 @@ static int pcistub_device_id_add(int dom
>  static int pcistub_device_id_remove(int domain, int bus, int slot, int func)
>  {
>       struct pcistub_device_id *pci_dev_id, *t;
> -     int devfn = PCI_DEVFN(slot, func);
>       int err = -ENOENT;
>       unsigned long flags;
>  
>       spin_lock_irqsave(&device_ids_lock, flags);
>       list_for_each_entry_safe(pci_dev_id, t, &pcistub_device_ids,
>                                slot_list) {
> -             if (pci_dev_id->domain == domain
> -                 && pci_dev_id->bus == bus && pci_dev_id->devfn == devfn) {
> +             if (pci_dev_id->domain == domain && pci_dev_id->bus == bus
> +                 && (slot < 0 || PCI_SLOT(pci_dev_id->devfn) == slot)
> +                 && (func < 0 || PCI_FUNC(pci_dev_id->devfn) == func)) {
>                       /* Don't break; here because it's possible the same
>                        * slot could be in the list more than once
>                        */
> @@ -1216,6 +1253,10 @@ static ssize_t permissive_add(struct dev
>       err = str_to_slot(buf, &domain, &bus, &slot, &func);
>       if (err)
>               goto out;
> +     if (slot < 0 || func < 0) {
> +             err = -EINVAL;
> +             goto out;
> +     }
>       psdev = pcistub_device_find(domain, bus, slot, func);
>       if (!psdev) {
>               err = -ENODEV;
> @@ -1297,17 +1338,51 @@ static int __init pcistub_init(void)
>  
>       if (pci_devs_to_hide && *pci_devs_to_hide) {
>               do {
> +                     char wc = '*';
> +
>                       parsed = 0;
>  
>                       err = sscanf(pci_devs_to_hide + pos,
>                                    " (%x:%x:%x.%x) %n",
>                                    &domain, &bus, &slot, &func, &parsed);
> -                     if (err != 4) {
> +                     switch (err) {
> +                     case 3:
> +                             func = -1;
> +                             err = sscanf(pci_devs_to_hide + pos,
> +                                          " (%x:%x:%x.%c) %n",
> +                                          &domain, &bus, &slot, &wc,
> +                                          &parsed);
> +                             break;
> +                     case 2:
> +                             slot = func = -1;
> +                             err = sscanf(pci_devs_to_hide + pos,
> +                                          " (%x:%x:*.%c) %n",
> +                                          &domain, &bus, &wc, &parsed) + 1;
> +                             break;
> +                     }
> +
> +                     if (err != 4 || wc != '*') {
>                               domain = 0;
> +                             wc = '*';
>                               err = sscanf(pci_devs_to_hide + pos,
>                                            " (%x:%x.%x) %n",
>                                            &bus, &slot, &func, &parsed);
> -                             if (err != 3)
> +                             switch (err) {
> +                             case 2:
> +                                     func = -1;
> +                                     err = sscanf(pci_devs_to_hide + pos,
> +                                                  " (%x:%x.%c) %n",
> +                                                  &bus, &slot, &wc,
> +                                                  &parsed);
> +                                     break;
> +                             case 1:
> +                                     slot = func = -1;
> +                                     err = sscanf(pci_devs_to_hide + pos,
> +                                                  " (%x:*.%c) %n",
> +                                                  &bus, &wc, &parsed) + 1;
> +                                     break;
> +                             }
> +                             if (err != 3 || wc != '*')
>                                       goto parse_error;
>                       }
>  
> 

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