On 05/02/16 16:50, Boris Ostrovsky wrote:
>
>
> On 02/05/2016 08:21 AM, Juergen Gross wrote:
>> When adding more than one LUN to a frontend a warning for a failed
>> assignment is issued in dom0 for each already existing LUN. Avoid this
>> warning.
>
> Aren't you just factoring out the check? The warning is still printed
> for each scsiback_add_translation_entry() invocation, no?
I don't call scsiback_add_translation_entry() in the critical case.
>
>
>>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
>> ---
>> drivers/xen/xen-scsiback.c | 65
>> ++++++++++++++++++++++++++--------------------
>> 1 file changed, 37 insertions(+), 28 deletions(-)
>>
>> diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
>> index 51387d7..69de879 100644
>> --- a/drivers/xen/xen-scsiback.c
>> +++ b/drivers/xen/xen-scsiback.c
>> @@ -849,15 +849,31 @@ static int scsiback_map(struct vscsibk_info *info)
>> }
>> /*
>> + Check for a translation entry being present
>> +*/
>> +static struct v2p_entry *scsiback_chk_translation_entry(
>> + struct vscsibk_info *info, struct ids_tuple *v)
>> +{
>> + struct list_head *head = &(info->v2p_entry_lists);
>> + struct v2p_entry *entry;
>> +
>> + list_for_each_entry(entry, head, l)
>> + if ((entry->v.chn == v->chn) &&
>> + (entry->v.tgt == v->tgt) &&
>> + (entry->v.lun == v->lun))
>> + return entry;
>> +
>> + return NULL;
>> +}
>> +
>> +/*
>> Add a new translation entry
>> */
>> static int scsiback_add_translation_entry(struct vscsibk_info *info,
>> char *phy, struct ids_tuple *v)
>> {
>> int err = 0;
>> - struct v2p_entry *entry;
>> struct v2p_entry *new;
>> - struct list_head *head = &(info->v2p_entry_lists);
>> unsigned long flags;
>> char *lunp;
>> unsigned long long unpacked_lun;
>> @@ -917,15 +933,10 @@ static int scsiback_add_translation_entry(struct
>> vscsibk_info *info,
>> spin_lock_irqsave(&info->v2p_lock, flags);
>> /* Check double assignment to identical virtual ID */
>> - list_for_each_entry(entry, head, l) {
>> - if ((entry->v.chn == v->chn) &&
>> - (entry->v.tgt == v->tgt) &&
>> - (entry->v.lun == v->lun)) {
>> - pr_warn("Virtual ID is already used. Assignment was not
>> performed.\n");
>> - err = -EEXIST;
>> - goto out;
>> - }
>> -
>> + if (scsiback_chk_translation_entry(info, v)) {
>> + pr_warn("Virtual ID is already used. Assignment was not
>> performed.\n");
>> + err = -EEXIST;
>> + goto out;
>> }
>> /* Create a new translation entry and add to the list */
>> @@ -933,7 +944,7 @@ static int scsiback_add_translation_entry(struct
>> vscsibk_info *info,
>> new->v = *v;
>> new->tpg = tpg;
>> new->lun = unpacked_lun;
>> - list_add_tail(&new->l, head);
>> + list_add_tail(&new->l, &info->v2p_entry_lists);
>> out:
>> spin_unlock_irqrestore(&info->v2p_lock, flags);
>> @@ -962,33 +973,31 @@ static int scsiback_del_translation_entry(struct
>> vscsibk_info *info,
>> struct ids_tuple *v)
>> {
>> struct v2p_entry *entry;
>> - struct list_head *head = &(info->v2p_entry_lists);
>> unsigned long flags;
>> spin_lock_irqsave(&info->v2p_lock, flags);
>> /* Find out the translation entry specified */
>> - list_for_each_entry(entry, head, l) {
>> - if ((entry->v.chn == v->chn) &&
>> - (entry->v.tgt == v->tgt) &&
>> - (entry->v.lun == v->lun)) {
>> - goto found;
>> - }
>> - }
>> -
>> - spin_unlock_irqrestore(&info->v2p_lock, flags);
>> - return 1;
>> -
>> -found:
>> - /* Delete the translation entry specfied */
>> - __scsiback_del_translation_entry(entry);
>> + entry = scsiback_chk_translation_entry(info, v);
>> + if (entry)
>> + __scsiback_del_translation_entry(entry);
>> spin_unlock_irqrestore(&info->v2p_lock, flags);
>> - return 0;
>> + return entry == NULL;
>
> Might be better to return -ENOENT instead of 1 above and -EEXISTS if
> entry!=NULL, given that this returns an int.
I just didn't want to change more than necessary. In case it is
okay to do some cleanup as well I'd rather change the return type
to "bool".
Juergen
>
> -boris
>
>> }
>> static void scsiback_do_add_lun(struct vscsibk_info *info, const
>> char *state,
>> char *phy, struct ids_tuple *vir, int try)
>> {
>> + struct v2p_entry *entry;
>> + unsigned long flags;
>> +
>> + if (try) {
>> + spin_lock_irqsave(&info->v2p_lock, flags);
>> + entry = scsiback_chk_translation_entry(info, vir);
>> + spin_unlock_irqrestore(&info->v2p_lock, flags);
>> + if (entry)
>> + return;
>> + }
>> if (!scsiback_add_translation_entry(info, phy, vir)) {
>> if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
>> "%d", XenbusStateInitialised)) {
>
>
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