Re: [ofa-general][PATCH 4/4] SRP fail-over faster

Vu Pham
2009-10-22T23:17:43Z

[-- Attachment #1: Type: text/plain, Size: 1278 bytes --]

Bart Van Assche wrote:
>
>>
>> +static void srp_event_handler(struct ib_event_handler *handler,
>> + struct ib_event *event)
>> +{
>> + struct srp_device *srp_dev =
>> + ib_get_client_data(event->device, &srp_client);
>> + struct srp_host *host, *tmp_host;
>> + struct srp_target_port *target, *tmp_target;
>> +
>> + if (!srp_dev || srp_dev->dev != event->device)
>> + return;
>> +
>> + printk(KERN_WARNING PFX "ASYNC event= %d on device= %s\n",
>> + event->event, srp_dev->dev->name);
>> +
>> + switch (event->event) {
>> + case IB_EVENT_PORT_ERR:
>> + list_for_each_entry_safe(host, tmp_host,
>> + &srp_dev->dev_list, list) {
>> + if (event->element.port_num == host->port) {
>> + spin_lock(&host->target_lock);
>>
>
> Can srp_remove_work() be executed concurrently with
> srp_event_handler() ? In that case the above code isn't safe and the
> spin_lock(&host->target_lock) should be moved to just before
> list_for_each_entry_safe(). The current implementation can trigger
> reading deallocated memory.
>
>
Here is the updated patch to address the race

[-- Attachment #2: srp_4_async_event_handler.patch --]
[-- Type: text/plain, Size: 4754 bytes --]

Handling async local port events: port error, active, lid change...
Upon local port err, it will set up timer device_loss_timeout seconds to
reconnect. If local port active and there is timer, it will delete the timer

Signed-off-by: Vu Pham <vu-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

drivers/infiniband/ulp/srp/ib_srp.c | 85 +++++++++++++++++++++++++++++++++++
drivers/infiniband/ulp/srp/ib_srp.h | 2 +
2 files changed, 87 insertions(+), 0 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 12404d5..88dbc17 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -2058,6 +2058,81 @@ free_host:
return NULL;
}

+static void srp_event_handler(struct ib_event_handler *handler,
+ struct ib_event *event)
+{
+ struct srp_device *srp_dev =
+ ib_get_client_data(event->device, &srp_client);
+ struct srp_host *host, *tmp_host;
+ struct srp_target_port *target, *tmp_target;
+
+ if (!srp_dev || srp_dev->dev != event->device)
+ return;
+
+ printk(KERN_WARNING PFX "ASYNC event= %d on device= %s\n",
+ event->event, srp_dev->dev->name);
+
+ switch (event->event) {
+ case IB_EVENT_PORT_ERR:
+ spin_lock(&srp_dev->dev_lock);
+ list_for_each_entry_safe(host, tmp_host,
+ &srp_dev->dev_list, list) {
+ if (event->element.port_num == host->port) {
+ spin_lock(&host->target_lock);
+ list_for_each_entry_safe(target, tmp_target,
+ &host->target_list, list) {
+ unsigned long flags;
+
+ spin_lock_irqsave(target->scsi_host->host_lock,
+ flags);
+ if (!target->qp_in_error &&
+ target->state == SRP_TARGET_LIVE)
+ srp_qp_err_add_timer(target,
+ target->device_loss_timeout);
+ spin_unlock_irqrestore(target->scsi_host->host_lock,
+ flags);
+ }
+ spin_unlock(&host->target_lock);
+ }
+ }
+ spin_unlock(&srp_dev->dev_lock);
+ break;
+ case IB_EVENT_PORT_ACTIVE:
+ case IB_EVENT_LID_CHANGE:
+ case IB_EVENT_PKEY_CHANGE:
+ case IB_EVENT_SM_CHANGE:
+ spin_lock(&srp_dev->dev_lock);
+ list_for_each_entry_safe(host, tmp_host, &srp_dev->dev_list,
+ list) {
+ if (event->element.port_num == host->port) {
+ spin_lock(&host->target_lock);
+ list_for_each_entry_safe(target, tmp_target,
+ &host->target_list, list) {
+ unsigned long flags;
+
+ spin_lock_irqsave(target->scsi_host->host_lock,
+ flags);
+ if (timer_pending(&target->qp_err_timer)
+ && !target->qp_in_error) {
+ shost_printk(KERN_WARNING PFX,
+ target->scsi_host,
+ "delete qp_in_err timer\n");
+ del_timer(&target->qp_err_timer);
+ }
+ spin_unlock_irqrestore(target->scsi_host->host_lock,
+ flags);
+ }
+ spin_unlock(&host->target_lock);
+ }
+ }
+ spin_unlock(&srp_dev->dev_lock);
+ break;
+ default:
+ break;
+ }
+
+}
+
static void srp_add_one(struct ib_device *device)
{
struct srp_device *srp_dev;
@@ -2090,6 +2165,7 @@ static void srp_add_one(struct ib_device *device)
srp_dev->fmr_page_mask = ~((u64) srp_dev->fmr_page_size - 1);

INIT_LIST_HEAD(&srp_dev->dev_list);
+ spin_lock_init(&srp_dev->dev_lock);

srp_dev->dev = device;
srp_dev->pd = ib_alloc_pd(device);
@@ -2103,6 +2179,11 @@ static void srp_add_one(struct ib_device *device)
if (IS_ERR(srp_dev->mr))
goto err_pd;

+ INIT_IB_EVENT_HANDLER(&srp_dev->event_handler, srp_dev->dev,
+ srp_event_handler);
+ if (ib_register_event_handler(&srp_dev->event_handler))
+ goto err_pd;
+
memset(&fmr_param, 0, sizeof fmr_param);
fmr_param.pool_size = SRP_FMR_POOL_SIZE;
fmr_param.dirty_watermark = SRP_FMR_DIRTY_SIZE;
@@ -2154,6 +2235,9 @@ static void srp_remove_one(struct ib_device *device)

srp_dev = ib_get_client_data(device, &srp_client);

+ ib_unregister_event_handler(&srp_dev->event_handler);
+
+ spin_lock(&srp_dev->dev_lock);
list_for_each_entry_safe(host, tmp_host, &srp_dev->dev_list, list) {
device_unregister(&host->dev);
/*
@@ -2193,6 +2277,7 @@ static void srp_remove_one(struct ib_device *device)

kfree(host);
}
+ spin_unlock(&srp_dev->dev_lock);

if (srp_dev->fmr_pool)
ib_destroy_fmr_pool(srp_dev->fmr_pool);
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index daa4bf7..74d1f09 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -86,8 +86,10 @@ enum srp_request_type {
struct srp_device {
struct list_head dev_list;
struct ib_device *dev;
+ spinlock_t dev_lock;
struct ib_pd *pd;
struct ib_mr *mr;
+ struct ib_event_handler event_handler;
struct ib_fmr_pool *fmr_pool;
int fmr_page_shift;
int fmr_page_size;