scsi: core: Avoid leaving shost->last_reset with stale value if EH does not run

The changes to issue the abort from the scmd->abort_work instead of the EH
thread introduced a problem if eh_deadline is used.  If aborting the
command(s) is successful, and there are never any scmds added to the
shost->eh_cmd_q, there is no code path which will reset the ->last_reset
value back to zero.

The effect of this is that after a successful abort with no EH thread
activity, a subsequent timeout, perhaps a long time later, might
immediately be considered past a user-set eh_deadline time, and the host
will be reset with no attempt at recovery.

Fix this by resetting ->last_reset back to zero in scmd_eh_abort_handler()
if it is determined that the EH thread will not run to do this.

Thanks to Gopinath Marappan for investigating this problem.

Link: https://lore.kernel.org/r/20211029194311.17504-2-emilne@redhat.com
Fixes: e494f6a72839 ("[SCSI] improved eh timeout handler")
Cc: stable@vger.kernel.org
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 17aef936bc9063f09fb69b530727cf2e02ff70b5..2cb7163e24cc6f21c458d36d52c17f7f6123cc74 100644 (file)
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -387,6 +387,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
        shost->shost_state = SHOST_CREATED;
        INIT_LIST_HEAD(&shost->__devices);
        INIT_LIST_HEAD(&shost->__targets);
+       INIT_LIST_HEAD(&shost->eh_abort_list);
        INIT_LIST_HEAD(&shost->eh_cmd_q);
        INIT_LIST_HEAD(&shost->starved_list);
        init_waitqueue_head(&shost->host_wait);

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 3de03925550e51ebc357f97c1d3a17ad3e255b0f..bdf782d9cb86f30d28bf712b98d927603f28c1de 100644 (file)
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -133,6 +133,23 @@ static bool scsi_eh_should_retry_cmd(struct scsi_cmnd *cmd)
        return true;
 }
 
+static void scsi_eh_complete_abort(struct scsi_cmnd *scmd, struct Scsi_Host *shost)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(shost->host_lock, flags);
+       list_del_init(&scmd->eh_entry);
+       /*
+        * If the abort succeeds, and there is no further
+        * EH action, clear the ->last_reset time.
+        */
+       if (list_empty(&shost->eh_abort_list) &&
+           list_empty(&shost->eh_cmd_q))
+               if (shost->eh_deadline != -1)
+                       shost->last_reset = 0;
+       spin_unlock_irqrestore(shost->host_lock, flags);
+}
+
 /**
  * scmd_eh_abort_handler - Handle command aborts
  * @work:      command to be aborted.
@@ -150,6 +167,7 @@ scmd_eh_abort_handler(struct work_struct *work)
                container_of(work, struct scsi_cmnd, abort_work.work);
        struct scsi_device *sdev = scmd->device;
        enum scsi_disposition rtn;
+       unsigned long flags;
 
        if (scsi_host_eh_past_deadline(sdev->host)) {
                SCSI_LOG_ERROR_RECOVERY(3,
@@ -173,12 +191,14 @@ scmd_eh_abort_handler(struct work_struct *work)
                                SCSI_LOG_ERROR_RECOVERY(3,
                                        scmd_printk(KERN_WARNING, scmd,
                                                    "retry aborted command\n"));
+                               scsi_eh_complete_abort(scmd, sdev->host);
                                scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
                                return;
                        } else {
                                SCSI_LOG_ERROR_RECOVERY(3,
                                        scmd_printk(KERN_WARNING, scmd,
                                                    "finish aborted command\n"));
+                               scsi_eh_complete_abort(scmd, sdev->host);
                                scsi_finish_command(scmd);
                                return;
                        }
@@ -191,6 +211,9 @@ scmd_eh_abort_handler(struct work_struct *work)
                }
        }
 
+       spin_lock_irqsave(sdev->host->host_lock, flags);
+       list_del_init(&scmd->eh_entry);
+       spin_unlock_irqrestore(sdev->host->host_lock, flags);
        scsi_eh_scmd_add(scmd);
 }
 
@@ -221,6 +244,8 @@ scsi_abort_command(struct scsi_cmnd *scmd)
        spin_lock_irqsave(shost->host_lock, flags);
        if (shost->eh_deadline != -1 && !shost->last_reset)
                shost->last_reset = jiffies;
+       BUG_ON(!list_empty(&scmd->eh_entry));
+       list_add_tail(&scmd->eh_entry, &shost->eh_abort_list);
        spin_unlock_irqrestore(shost->host_lock, flags);
 
        scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED;

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index d0b7c6dc74f88f15a577e504f54519f514f31ce0..c851c05d6091e5613d4205554fddcb4c6f8f89b9 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1143,6 +1143,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
        cmd->sense_buffer = buf;
        cmd->prot_sdb = prot;
        cmd->flags = flags;
+       INIT_LIST_HEAD(&cmd->eh_entry);
        INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
        cmd->jiffies_at_alloc = jiffies_at_alloc;
        cmd->retries = retries;

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 7958a604f979dd91e879434d033dafb8dceebb03..29ac40cf1aaeebebd61432de478ecb0c155d72a3 100644 (file)
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -73,7 +73,7 @@ enum scsi_cmnd_submitter {
 struct scsi_cmnd {
        struct scsi_request req;
        struct scsi_device *device;
-       struct list_head eh_entry; /* entry for the host eh_cmd_q */
+       struct list_head eh_entry; /* entry for the host eh_abort_list/eh_cmd_q */
        struct delayed_work abort_work;
 
        struct rcu_head rcu;

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index ae715959f886abf722bd8602c35c083ec2e09740..ebe059badba0e53405c4142532b0ed600adf9dc1 100644 (file)
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -551,6 +551,7 @@ struct Scsi_Host {
 
        struct mutex            scan_mutex;/* serialize scanning activity */
 
+       struct list_head        eh_abort_list;
        struct list_head        eh_cmd_q;
        struct task_struct    * ehandler;  /* Error recovery thread. */
        struct completion     * eh_action; /* Wait for specific actions on the