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Subject[PATCH v2] libsas: Don't give scsi_cmnds to the EH if they never made it to the SAS LLDD or have already returned
On a system with many SAS targets, it appears possible that a scsi_cmnd
can time out without ever making it to the SAS LLDD or at the same time
that a completion is occurring. In both of these cases, telling the
LLDD to abort the sas_task makes no sense because the LLDD won't know
about the sas_task; what we really want to do is to increase the timer.
Note that this involves creating another sas_task bit to indicate
whether or not the task has been sent to the LLDD; I could have
implemented this by slightly redefining SAS_TASK_STATE_PENDING, but
this way seems cleaner.

This second version amends the aic94xx portion to set the
TASK_AT_INITIATOR flag for all sas_tasks that were passed to
lldd_execute_task.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---

drivers/scsi/aic94xx/aic94xx_task.c | 9 +++++++++
drivers/scsi/aic94xx/aic94xx_tmf.c | 4 +++-
drivers/scsi/libsas/sas_scsi_host.c | 7 +++++++
include/scsi/libsas.h | 1 +
4 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/drivers/scsi/aic94xx/aic94xx_task.c b/drivers/scsi/aic94xx/aic94xx_task.c
index d202ed5..e2ad5be 100644
--- a/drivers/scsi/aic94xx/aic94xx_task.c
+++ b/drivers/scsi/aic94xx/aic94xx_task.c
@@ -349,6 +349,7 @@ Again:

spin_lock_irqsave(&task->task_state_lock, flags);
task->task_state_flags &= ~SAS_TASK_STATE_PENDING;
+ task->task_state_flags &= ~SAS_TASK_AT_INITIATOR;
task->task_state_flags |= SAS_TASK_STATE_DONE;
if (unlikely((task->task_state_flags & SAS_TASK_STATE_ABORTED))) {
spin_unlock_irqrestore(&task->task_state_lock, flags);
@@ -557,6 +558,7 @@ int asd_execute_task(struct sas_task *ta
struct sas_task *t = task;
struct asd_ascb *ascb = NULL, *a;
struct asd_ha_struct *asd_ha = task->dev->port->ha->lldd_ha;
+ unsigned long flags;

res = asd_can_queue(asd_ha, num);
if (res)
@@ -599,6 +601,10 @@ int asd_execute_task(struct sas_task *ta
}
if (res)
goto out_err_unmap;
+
+ spin_lock_irqsave(&t->task_state_lock, flags);
+ t->task_state_flags |= SAS_TASK_AT_INITIATOR;
+ spin_unlock_irqrestore(&t->task_state_lock, flags);
}
list_del_init(&alist);

@@ -617,6 +623,9 @@ out_err_unmap:
if (a == b)
break;
t = a->uldd_task;
+ spin_lock_irqsave(&t->task_state_lock, flags);
+ t->task_state_flags &= ~SAS_TASK_AT_INITIATOR;
+ spin_unlock_irqrestore(&t->task_state_lock, flags);
switch (t->task_proto) {
case SATA_PROTO:
case SAS_PROTO_STP:
diff --git a/drivers/scsi/aic94xx/aic94xx_tmf.c b/drivers/scsi/aic94xx/aic94xx_tmf.c
index 6123438..686cea1 100644
--- a/drivers/scsi/aic94xx/aic94xx_tmf.c
+++ b/drivers/scsi/aic94xx/aic94xx_tmf.c
@@ -345,7 +345,7 @@ static inline int asd_clear_nexus(struct
int asd_abort_task(struct sas_task *task)
{
struct asd_ascb *tascb = task->lldd_task;
- struct asd_ha_struct *asd_ha = tascb->ha;
+ struct asd_ha_struct *asd_ha;
int res = 1;
unsigned long flags;
struct asd_ascb *ascb = NULL;
@@ -360,6 +360,8 @@ int asd_abort_task(struct sas_task *task
}
spin_unlock_irqrestore(&task->task_state_lock, flags);

+ asd_ha = tascb->ha;
+
ascb = asd_ascb_alloc_list(asd_ha, &res, GFP_KERNEL);
if (!ascb)
return -ENOMEM;
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index e064aac..c3fc8d6 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -542,6 +542,13 @@ enum scsi_eh_timer_return sas_scsi_timed
cmd, task);
return EH_HANDLED;
}
+ if (!(task->task_state_flags & SAS_TASK_AT_INITIATOR)) {
+ spin_unlock_irqrestore(&task->task_state_lock, flags);
+ SAS_DPRINTK("command 0x%p, task 0x%p, not at initiator: "
+ "EH_RESET_TIMER\n",
+ cmd, task);
+ return EH_RESET_TIMER;
+ }
task->task_state_flags |= SAS_TASK_STATE_ABORTED;
spin_unlock_irqrestore(&task->task_state_lock, flags);

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index c4a8af1..33b72ae 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -538,6 +538,7 @@ #define SAS_TASK_STATE_PENDING 1
#define SAS_TASK_STATE_DONE 2
#define SAS_TASK_STATE_ABORTED 4
#define SAS_TASK_INITIATOR_ABORTED 8
+#define SAS_TASK_AT_INITIATOR 16

static inline struct sas_task *sas_alloc_task(gfp_t flags)
{
-
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