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

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

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@suse.com>
> 
> ---
>  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;
>  			}
>  
>