Re: [PATCH 14/20] scsi_dh_alua: update all port states

[Hannes Reinecke]

On 12/30/2015 02:23 PM, Christoph Hellwig wrote:

On Tue, Dec 08, 2015 at 08:37:34AM +0100, Hannes Reinecke wrote:

When we read in the target port group state we should be
updating all affected port groups, otherwise we risk
running out of sync.


Why would we ever have multiple alua_port_group structures for the
same port that we'd need to iterate here?


That is the whole point :-)
The index into the port_group structure is the tuple
(LUN ID, group ID), where each tuple corresponds to a different/separate 
port group state.
So for each LUN ID we will have at least two port_group structures, the 
states of which will be returned per call to REPORT TARGET PORT GROUPS.
And as the other paths might be unavailable we might not be able to 
execute REPORT TARGET PORT GROUPS at all. So we need to update it here.


Cheers,

Hannes
--
Dr. Hannes Reinecke   zSeries & Storage
h...@suse.de  +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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Re: [PATCH 14/20] scsi_dh_alua: update all port states

[Christoph Hellwig]

On Tue, Dec 08, 2015 at 08:37:34AM +0100, Hannes Reinecke wrote:
> When we read in the target port group state we should be
> updating all affected port groups, otherwise we risk
> running out of sync.

Why would we ever have multiple alua_port_group structures for the
same port that we'd need to iterate here?
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[PATCH 14/20] scsi_dh_alua: update all port states

[Hannes Reinecke]

When we read in the target port group state we should be
updating all affected port groups, otherwise we risk
running out of sync.

Signed-off-by: Hannes Reinecke 
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 31 +-
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
b/drivers/scsi/device_handler/scsi_dh_alua.c
index 04a3a543..6ddbb88 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -499,11 +499,13 @@ static int alua_check_sense(struct scsi_device *sdev,
 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 {
struct scsi_sense_hdr sense_hdr;
+   struct alua_port_group *tmp_pg;
int len, k, off, valid_states = 0, bufflen = ALUA_RTPG_SIZE;
-   unsigned char *ucp, *buff;
+   unsigned char *desc, *buff;
unsigned err, retval;
unsigned int tpg_desc_tbl_off;
unsigned char orig_transition_tmo;
+   unsigned long flags;
 
if (!pg->expiry) {
unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
@@ -605,16 +607,27 @@ static int alua_rtpg(struct scsi_device *sdev, struct 
alua_port_group *pg)
else
tpg_desc_tbl_off = 4;
 
-   for (k = tpg_desc_tbl_off, ucp = buff + tpg_desc_tbl_off;
+   for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 k < len;
-k += off, ucp += off) {
-
-   if (pg->group_id == get_unaligned_be16([2])) {
-   pg->state = ucp[0] & 0x0f;
-   pg->pref = ucp[0] >> 7;
-   valid_states = ucp[1];
+k += off, desc += off) {
+   u16 group_id = get_unaligned_be16([2]);
+
+   spin_lock_irqsave(_group_lock, flags);
+   list_for_each_entry(tmp_pg, _group_list, node) {
+   if (tmp_pg->group_id != group_id)
+   continue;
+   if (tmp_pg->device_id_len != pg->device_id_len)
+   continue;
+   if (strncmp(tmp_pg->device_id_str, pg->device_id_str,
+   tmp_pg->device_id_len))
+   continue;
+   tmp_pg->state = desc[0] & 0x0f;
+   tmp_pg->pref = desc[0] >> 7;
+   if (tmp_pg == pg)
+   valid_states = desc[1];
}
-   off = 8 + (ucp[7] * 4);
+   spin_unlock_irqrestore(_group_lock, flags);
+   off = 8 + (desc[7] * 4);
}
 
sdev_printk(KERN_INFO, sdev,
-- 
1.8.5.6

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