Re: [PATCH v2] scsi: libsas: defer ata device eh commands to libata

[John Garry]

On 07/03/2018 09:18, Jack Wang wrote:
2018-03-07 8:47 GMT+01:00 Jason Yan <yanai...@huawei.com>:
When ata device doing EH, some commands still attached with tasks are not
passed to libata when abort failed or recover failed, so libata did not
handle these commands. After these commands done, sas task is freed, but
ata qc is not freed. This will cause ata qc leak and trigger a warning
like below:
WARNING: CPU: 0 PID: 28512 at drivers/ata/libata-eh.c:4037
ata_eh_finish+0xb4/0xcc
CPU: 0 PID: 28512 Comm: kworker/u32:2 Tainted: G     W  OE 4.14.0#1
......
Call trace:
[<ffff0000088b7bd0>] ata_eh_finish+0xb4/0xcc
[<ffff0000088b8420>] ata_do_eh+0xc4/0xd8
[<ffff0000088b8478>] ata_std_error_handler+0x44/0x8c
[<ffff0000088b8068>] ata_scsi_port_error_handler+0x480/0x694
[<ffff000008875fc4>] async_sas_ata_eh+0x4c/0x80
[<ffff0000080f6be8>] async_run_entry_fn+0x4c/0x170
[<ffff0000080ebd70>] process_one_work+0x144/0x390
[<ffff0000080ec100>] worker_thread+0x144/0x418
[<ffff0000080f2c98>] kthread+0x10c/0x138
[<ffff0000080855dc>] ret_from_fork+0x10/0x18

If ata qc leaked too many, ata tag allocation will fail and io blocked
for ever.

As suggested by Dan Williams, defer ata device commands to libata and
merge sas_eh_finish_cmd() with sas_eh_defer_cmd(). libata will handle
ata qcs correctly after this.

Signed-off-by: Jason Yan <yanai...@huawei.com>
CC: Xiaofei Tan <tanxiao...@huawei.com>
CC: John Garry <john.ga...@huawei.com>
CC: Dan Williams <dan.j.willi...@intel.com>
Hi Jason,

Would be good if you add the Fixes tag, so distribution could pick it up easily.
And wasn't the idea to delete sas_eh_finish_cmd instead of sas_eh_defer_cmd?

The problem was that we need to defer any ATA command. So the solution 
was to just delete sas_eh_defer_cmd() and make sas_eh_finish_cmd() do 
what needs to be done for either ATA or non-ATA task.

Thanks,
John



Thanks,
Jack
---
 drivers/scsi/libsas/sas_scsi_host.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/drivers/scsi/libsas/sas_scsi_host.c 
b/drivers/scsi/libsas/sas_scsi_host.c
index 6de9681ace82..fd76436b289c 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -223,6 +223,7 @@ int sas_queuecommand(struct Scsi_Host *host, struct 
scsi_cmnd *cmd)
 static void sas_eh_finish_cmd(struct scsi_cmnd *cmd)
 {
        struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(cmd->device->host);
+       struct domain_device *dev = cmd_to_domain_dev(cmd);
        struct sas_task *task = TO_SAS_TASK(cmd);

        /* At this point, we only get called following an actual abort
@@ -231,6 +232,11 @@ static void sas_eh_finish_cmd(struct scsi_cmnd *cmd)
         */
        sas_end_task(cmd, task);

+       if (dev_is_sata(dev)) {
+               list_move_tail(&cmd->eh_entry, &sas_ha->eh_ata_q);
+               return;
+       }
+
        /* now finish the command and move it on to the error
         * handler done list, this also takes it off the
         * error handler pending list.
@@ -238,22 +244,6 @@ static void sas_eh_finish_cmd(struct scsi_cmnd *cmd)
        scsi_eh_finish_cmd(cmd, &sas_ha->eh_done_q);
 }

-static void sas_eh_defer_cmd(struct scsi_cmnd *cmd)
-{
-       struct domain_device *dev = cmd_to_domain_dev(cmd);
-       struct sas_ha_struct *ha = dev->port->ha;
-       struct sas_task *task = TO_SAS_TASK(cmd);
-
-       if (!dev_is_sata(dev)) {
-               sas_eh_finish_cmd(cmd);
-               return;
-       }
-
-       /* report the timeout to libata */
-       sas_end_task(cmd, task);
-       list_move_tail(&cmd->eh_entry, &ha->eh_ata_q);
-}
-
 static void sas_scsi_clear_queue_lu(struct list_head *error_q, struct 
scsi_cmnd *my_cmd)
 {
        struct scsi_cmnd *cmd, *n;
@@ -261,7 +251,7 @@ static void sas_scsi_clear_queue_lu(struct list_head 
*error_q, struct scsi_cmnd
        list_for_each_entry_safe(cmd, n, error_q, eh_entry) {
                if (cmd->device->sdev_target == my_cmd->device->sdev_target &&
                    cmd->device->lun == my_cmd->device->lun)
-                       sas_eh_defer_cmd(cmd);
+                       sas_eh_finish_cmd(cmd);
        }
 }

@@ -631,12 +621,12 @@ static void sas_eh_handle_sas_errors(struct Scsi_Host 
*shost, struct list_head *
                case TASK_IS_DONE:
                        SAS_DPRINTK("%s: task 0x%p is done\n", __func__,
                                    task);
-                       sas_eh_defer_cmd(cmd);
+                       sas_eh_finish_cmd(cmd);
                        continue;
                case TASK_IS_ABORTED:
                        SAS_DPRINTK("%s: task 0x%p is aborted\n",
                                    __func__, task);
-                       sas_eh_defer_cmd(cmd);
+                       sas_eh_finish_cmd(cmd);
                        continue;
                case TASK_IS_AT_LU:
                        SAS_DPRINTK("task 0x%p is at LU: lu recover\n", task);
@@ -647,7 +637,7 @@ static void sas_eh_handle_sas_errors(struct Scsi_Host 
*shost, struct list_head *
                                            "recovered\n",
                                            SAS_ADDR(task->dev),
                                            cmd->device->lun);
-                               sas_eh_defer_cmd(cmd);
+                               sas_eh_finish_cmd(cmd);
                                sas_scsi_clear_queue_lu(work_q, cmd);
                                goto Again;
                        }
--
2.13.6


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