linux-kernel - Re: [PATCH 2/2] shpchp: Rename duplicate slot name N as N-1, N-2, N-M...

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Date:	Thu, 31 Jul 2008 19:32:43 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	Alex Chiang <achiang@...com>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Matthew Wilcox <matthew@....cx>,
	Pierre Ossman <drzeus-list@...eus.cx>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org
Subject: Re: [PATCH 2/2] shpchp: Rename duplicate slot name N as N-1, N-2,
 N-M...

Tested-by & Acked-by: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>

Thnaks,
Kenji Kaneshige


Alex Chiang wrote:
> Commit ef0ff95f136f0f2d035667af5d18b824609de320 introduces the
> shpchp_slot_with_bus module parameter, which was intended to help
> work around broken firmware that assigns the same name to multiple
> slots.
> 
> Commit b3bd307c628af2f0a581c42d5d7e4bcdbbf64b6a tells the user to
> use the above parameter in the event of a name collision.
> 
> This approach is sub-optimal because it requires too much work from
> the user.
> 
> Instead, let's rename the slot on behalf of the user. If firmware
> assigns the name N to multiple slots, then:
> 
>         The first registered slot is assigned N
>         The second registered slot is assigned N-1
>         The third registered slot is assigned N-2
>         The Mth registered slot becomes N-M
> 
> In the event we overflow the slot->name parameter, we report an
> error to the user.
> 
> Signed-off-by: Alex Chiang <achiang@...com>
> ---
>  drivers/pci/hotplug/shpchp_core.c |   34 +++++++++++++++-------------------
>  1 files changed, 15 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/shpchp_core.c b/drivers/pci/hotplug/shpchp_core.c
> index a8cbd03..cc38615 100644
> --- a/drivers/pci/hotplug/shpchp_core.c
> +++ b/drivers/pci/hotplug/shpchp_core.c
> @@ -39,7 +39,6 @@
>  int shpchp_debug;
>  int shpchp_poll_mode;
>  int shpchp_poll_time;
> -static int shpchp_slot_with_bus;
>  struct workqueue_struct *shpchp_wq;
>  
>  #define DRIVER_VERSION	"0.4"
> @@ -53,11 +52,9 @@ MODULE_LICENSE("GPL");
>  module_param(shpchp_debug, bool, 0644);
>  module_param(shpchp_poll_mode, bool, 0644);
>  module_param(shpchp_poll_time, int, 0644);
> -module_param(shpchp_slot_with_bus, bool, 0644);
>  MODULE_PARM_DESC(shpchp_debug, "Debugging mode enabled or not");
>  MODULE_PARM_DESC(shpchp_poll_mode, "Using polling mechanism for hot-plug events or not");
>  MODULE_PARM_DESC(shpchp_poll_time, "Polling mechanism frequency, in seconds");
> -MODULE_PARM_DESC(shpchp_slot_with_bus, "Use bus number in the slot name");
>  
>  #define SHPC_MODULE_NAME "shpchp"
>  
> @@ -99,23 +96,13 @@ static void release_slot(struct hotplug_slot *hotplug_slot)
>  	kfree(slot);
>  }
>  
> -static void make_slot_name(struct slot *slot)
> -{
> -	if (shpchp_slot_with_bus)
> -		snprintf(slot->hotplug_slot->name, SLOT_NAME_SIZE, "%04d_%04d",
> -			 slot->bus, slot->number);
> -	else
> -		snprintf(slot->hotplug_slot->name, SLOT_NAME_SIZE, "%d",
> -			 slot->number);
> -}
> -
>  static int init_slots(struct controller *ctrl)
>  {
>  	struct slot *slot;
>  	struct hotplug_slot *hotplug_slot;
>  	struct hotplug_slot_info *info;
>  	int retval = -ENOMEM;
> -	int i;
> +	int i, len, dup = 1;
>  
>  	for (i = 0; i < ctrl->num_slots; i++) {
>  		slot = kzalloc(sizeof(*slot), GFP_KERNEL);
> @@ -146,7 +133,7 @@ static int init_slots(struct controller *ctrl)
>  		/* register this slot with the hotplug pci core */
>  		hotplug_slot->private = slot;
>  		hotplug_slot->release = &release_slot;
> -		make_slot_name(slot);
> +		snprintf(slot->name, SLOT_NAME_SIZE, "%d", slot->number);
>  		hotplug_slot->ops = &shpchp_hotplug_slot_ops;
>  
>  		get_power_status(hotplug_slot, &info->power_status);
> @@ -157,14 +144,23 @@ static int init_slots(struct controller *ctrl)
>  		dbg("Registering bus=%x dev=%x hp_slot=%x sun=%x "
>  		    "slot_device_offset=%x\n", slot->bus, slot->device,
>  		    slot->hp_slot, slot->number, ctrl->slot_device_offset);
> +duplicate_name:
>  		retval = pci_hp_register(slot->hotplug_slot,
>  				ctrl->pci_dev->subordinate, slot->device);
>  		if (retval) {
> +			/*
> +			 * If slot N already exists, we'll try to create
> +			 * slot N-1, N-2 ... N-M, until we overflow.
> +			 */
> +			if (retval == -EEXIST) {
> +				len = snprintf(slot->name, SLOT_NAME_SIZE,
> +					       "%d-%d", slot->number, dup++);
> +				if (len < SLOT_NAME_SIZE)
> +					goto duplicate_name;
> +				else
> +					err("duplicate slot name overflow\n");
> +			}
>  			err("pci_hp_register failed with error %d\n", retval);
> -			if (retval == -EEXIST)
> -				err("Failed to register slot because of name "
> -                                    "collision. Try \'shpchp_slot_with_bus\' "
> -				    "module option.\n");
>  			goto error_info;
>  		}
>  


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