[SCSI] libsas: close error handling vs sas_ata_task_done() race

Since sas_ata does not implement ->freeze(), completions for scmds and
internal commands can still arrive concurrent with
ata_scsi_cmd_error_handler() and sas_ata_post_internal() respectively.
By the time either of those is called libata has committed to completing
the qc, and the ATA_PFLAG_FROZEN flag tells sas_ata_task_done() it has
lost the race.

In the sas_ata_post_internal() case we take on the additional
responsibility of freeing the sas_task to close the race with
sas_ata_task_done() freeing the the task while sas_ata_post_internal()
is in the process of invoking ->lldd_abort_task().

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 0 insertions, 44 deletions

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 15533a17eb97..ba5876ccd29a 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -957,49 +957,6 @@ void sas_shutdown_queue(struct sas_ha_struct *sas_ha)
 }
 
 /*
- * Call the LLDD task abort routine directly.  This function is intended for
- * use by upper layers that need to tell the LLDD to abort a task.
- */
-int __sas_task_abort(struct sas_task *task)
-{
-        struct sas_internal *si =
-                to_sas_internal(task->dev->port->ha->core.shost->transportt);
-        unsigned long flags;
-        int res;
-
-        spin_lock_irqsave(&task->task_state_lock, flags);
-        if (task->task_state_flags & SAS_TASK_STATE_ABORTED ||
-            task->task_state_flags & SAS_TASK_STATE_DONE) {
-                spin_unlock_irqrestore(&task->task_state_lock, flags);
-                SAS_DPRINTK("%s: Task %p already finished.\n", __func__,
-                            task);
-                return 0;
-        }
-        task->task_state_flags |= SAS_TASK_STATE_ABORTED;
-        spin_unlock_irqrestore(&task->task_state_lock, flags);
-
-        if (!si->dft->lldd_abort_task)
-                return -ENODEV;
-
-        res = si->dft->lldd_abort_task(task);
-
-        spin_lock_irqsave(&task->task_state_lock, flags);
-        if ((task->task_state_flags & SAS_TASK_STATE_DONE) ||
-            (res == TMF_RESP_FUNC_COMPLETE))
-        {
-                spin_unlock_irqrestore(&task->task_state_lock, flags);
-                task->task_done(task);
-                return 0;
-        }
-
-        if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
-                task->task_state_flags &= ~SAS_TASK_STATE_ABORTED;
-        spin_unlock_irqrestore(&task->task_state_lock, flags);
-
-        return -EAGAIN;
-}
-
-/*
  * Tell an upper layer that it needs to initiate an abort for a given task.
  * This should only ever be called by an LLDD.
  */
@@ -1097,7 +1054,6 @@ EXPORT_SYMBOL_GPL(sas_slave_configure);
 EXPORT_SYMBOL_GPL(sas_change_queue_depth);
 EXPORT_SYMBOL_GPL(sas_change_queue_type);
 EXPORT_SYMBOL_GPL(sas_bios_param);
-EXPORT_SYMBOL_GPL(__sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_phy_reset);
 EXPORT_SYMBOL_GPL(sas_phy_enable);