[PATCH 5.14 008/849] scsi: core: Avoid leaving shost->last_reset with stale value if EH does not run

Greg Kroah-Hartman
2021-11-15T21:31:50Z

From: Ewan D. Milne <emilne@redhat.com>

commit 5ae17501bc62a49b0b193dcce003f16375f16654 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/hosts.c | 1 +
drivers/scsi/scsi_error.c | 25 +++++++++++++++++++++++++
drivers/scsi/scsi_lib.c | 1 +
include/scsi/scsi_cmnd.h | 2 +-
include/scsi/scsi_host.h | 1 +
5 files changed, 29 insertions(+), 1 deletion(-)

--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -388,6 +388,7 @@ struct Scsi_Host *scsi_host_alloc(struct
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);
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -135,6 +135,23 @@ static bool scsi_eh_should_retry_cmd(str
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.
@@ -152,6 +169,7 @@ scmd_eh_abort_handler(struct work_struct
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,
@@ -175,12 +193,14 @@ scmd_eh_abort_handler(struct work_struct
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;
}
@@ -193,6 +213,9 @@ scmd_eh_abort_handler(struct work_struct
}
}

+ 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);
}

@@ -223,6 +246,8 @@ scsi_abort_command(struct scsi_cmnd *scm
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;
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1136,6 +1136,7 @@ void scsi_init_command(struct scsi_devic
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;
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -68,7 +68,7 @@ struct scsi_pointer {
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;
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -556,6 +556,7 @@ 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