On Mon, 2016-02-08 at 15:34 +0100, Hannes Reinecke wrote:
> Track attached SCSI devices and update the 'access_state' field
> whenever an ALUA state change has been detected.
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 45 ++++++++++++++++++++++++++++--
> 1 file changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 51126b78..7bcc075 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -24,6 +24,7 @@
> #include <linux/module.h>
> #include <asm/unaligned.h>
> #include <scsi/scsi.h>
> +#include <scsi/scsi_proto.h>
> #include <scsi/scsi_dbg.h>
> #include <scsi/scsi_eh.h>
> #include <scsi/scsi_dh.h>
> @@ -75,6 +76,7 @@ struct alua_port_group {
> struct kref kref;
> struct rcu_head rcu;
> struct list_head node;
> + struct list_head dh_list;
> unsigned char device_id_str[256];
> int device_id_len;
> int group_id;
> @@ -92,6 +94,7 @@ struct alua_port_group {
> };
>
> struct alua_dh_data {
> + struct list_head node;
> struct alua_port_group *pg;
> int group_id;
> spinlock_t pg_lock;
> @@ -247,6 +250,7 @@ struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
> INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
> INIT_LIST_HEAD(&pg->rtpg_list);
> INIT_LIST_HEAD(&pg->node);
> + INIT_LIST_HEAD(&pg->dh_list);
> spin_lock_init(&pg->lock);
>
> spin_lock(&port_group_lock);
> @@ -328,6 +332,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
> {
> int rel_port = -1, group_id;
> struct alua_port_group *pg, *old_pg = NULL;
> + bool pg_updated;
> + unsigned long flags;
>
> group_id = scsi_vpd_tpg_id(sdev, &rel_port);
> if (group_id < 0) {
> @@ -357,13 +363,25 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
> old_pg = h->pg;
> if (old_pg != pg) {
> /* port group has changed. Update to new port group */
> + if (h->pg) {
> + spin_lock_irqsave(&old_pg->lock, flags);
> + list_del_rcu(&h->node);
> + spin_unlock_irqrestore(&old_pg->lock, flags);
> + }
> rcu_assign_pointer(h->pg, pg);
> + pg_updated = true;
> }
> if (sdev->synchronous_alua)
> pg->flags |= ALUA_SYNC_STPG;
> alua_rtpg_queue(h->pg, sdev, NULL, true);
> spin_unlock(&h->pg_lock);
>
> + if (pg_updated) {
> + spin_lock_irqsave(&pg->lock, flags);
> + list_add_rcu(&h->node, &pg->dh_list);
> + spin_unlock_irqrestore(&pg->lock, flags);
> + }
> +
> if (old_pg)
> kref_put(&old_pg->kref, release_port_group);
>
> @@ -613,8 +631,18 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
> if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
> if ((tmp_pg == pg) ||
> !(tmp_pg->flags & ALUA_PG_RUNNING)) {
> + struct alua_dh_data *h;
> +
> tmp_pg->state = desc[0] & 0x0f;
> tmp_pg->pref = desc[0] >> 7;
> + rcu_read_lock();
> + list_for_each_entry_rcu(h,
> + &tmp_pg->dh_list, node) {
> + /* h->sdev should always be valid */
> + BUG_ON(!h->sdev);
> + h->sdev->access_state = desc[0];
Here you did not mask desc[0] with 0x0f like you did in other places in the code.
> + }
> + rcu_read_unlock();
> }
> if (tmp_pg == pg)
> valid_states = desc[1];
> @@ -646,10 +674,19 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
> pg->interval = 2;
> err = SCSI_DH_RETRY;
> } else {
> + struct alua_dh_data *h;
> +
> /* Transitioning time exceeded, set port to standby */
> err = SCSI_DH_IO;
> pg->state = SCSI_ACCESS_STATE_STANDBY;
> pg->expiry = 0;
> + rcu_read_lock();
> + list_for_each_entry_rcu(h, &pg->dh_list, node) {
> + BUG_ON(!h->sdev);
> + h->sdev->access_state = (pg->state & 0x0f) |
> + (pg->pref << 7);
Since SCSI_ACCESS_STATE_PREFERRED is #defined as 0x80 in scsi_proto.h you
should use | (pg->pref ? SCSI_ACCESS_STATE_PREFERRED : 0) here rather than
just shifting, otherwise you will have a hard to find bug if somebody
changes the constant. (But I would prefer keeping them separate anyway.)
> + }
> + rcu_read_unlock();
> }
> break;
> case SCSI_ACCESS_STATE_OFFLINE:
> @@ -1053,6 +1090,7 @@ static int alua_bus_attach(struct scsi_device *sdev)
> rcu_assign_pointer(h->pg, NULL);
> h->init_error = SCSI_DH_OK;
> h->sdev = sdev;
> + INIT_LIST_HEAD(&h->node);
>
> mutex_init(&h->init_mutex);
> err = alua_initialize(sdev, h);
> @@ -1082,9 +1120,12 @@ static void alua_bus_detach(struct scsi_device *sdev)
> rcu_assign_pointer(h->pg, NULL);
> h->sdev = NULL;
> spin_unlock(&h->pg_lock);
> - if (pg)
> + if (pg) {
> + spin_lock(&pg->lock);
> + list_del_rcu(&h->node);
> + spin_unlock(&pg->lock);
> kref_put(&pg->kref, release_port_group);
> -
> + }
> sdev->handler_data = NULL;
> kfree(h);
> }
Reviewed-by: Ewan D. Milne <emilne@xxxxxxxxxx>
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