FAILED: patch "[PATCH] target: Fix LUN_RESET active TMR descriptor handling" failed to apply to 3.14-stable tree

PATCH [email protected] 1 participant 1 message Mar 1, 2016

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2016-03-01 21:51 UTC #0 lore raw

The patch below does not apply to the 3.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From a6d9bb1c9605cd4f44e2d8290dc4d0e88f20292d Mon Sep 17 00:00:00 2001

From: Nicholas Bellinger <[email protected]>
Date: Mon, 11 Jan 2016 21:53:05 -0800
Subject: [PATCH] target: Fix LUN_RESET active TMR descriptor handling

This patch fixes a NULL pointer se_cmd->cmd_kref < 0 refcount bug during TMR LUN_RESET with active TMRs, triggered during se_cmd + se_tmr_req descriptor shutdown + release via core_tmr_drain_tmr_list().

To address this bug, go ahead and obtain a local kref_get_unless_zero(&se_cmd->cmd_kref) for active I/O to set CMD_T_ABORTED, and transport_wait_for_tasks() followed by the final target_put_sess_cmd() to drop the local ->cmd_kref.

Also add two new checks within target_tmr_work() to avoid CMD_T_ABORTED -> TFO->queue_tm_rsp() callbacks ahead of invoking the backend -> fabric put in transport_cmd_check_stop_to_fabric().

For good measure, also change core_tmr_release_req() to use list_del_init() ahead of se_tmr_req memory free.

Reviewed-by Quinn Tran <[email protected]>

Cc Himanshu Madhani <[email protected]>

Cc Sagi Grimberg <[email protected]>

Cc Christoph Hellwig <[email protected]>

Cc Hannes Reinecke <[email protected]>

Cc Andy Grover <[email protected]>

Cc Mike Christie <[email protected]>

Cc [email protected] # 3.10+

Signed-off-by Nicholas Bellinger <[email protected]>

drivers/target/target_core_tmr.c +21 -1

index fb3decc28589..072af07bd2ff 100644
@@ -68,7 +68,7 @@ void core_tmr_release_req(struct se_tmr_req *tmr)
 
 	if (dev) {
 		spin_lock_irqsave(&dev->se_tmr_lock, flags);
-		list_del(&tmr->tmr_list);
+		list_del_init(&tmr->tmr_list);
 		spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
 	}

@@ -194,9 +194,11 @@ static void core_tmr_drain_tmr_list(
 	struct list_head *preempt_and_abort_list)
 {
 	LIST_HEAD(drain_tmr_list);
+	struct se_session *sess;
 	struct se_tmr_req *tmr_p, *tmr_pp;
 	struct se_cmd *cmd;
 	unsigned long flags;
+	bool rc;
 	/*
 	 * Release all pending and outgoing TMRs aside from the received
 	 * LUN_RESET tmr..

@@ -222,17 +224,31 @@ static void core_tmr_drain_tmr_list(
 		if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))
 			continue;
 
+		sess = cmd->se_sess;
+		if (WARN_ON_ONCE(!sess))
+			continue;
+
+		spin_lock(&sess->sess_cmd_lock);
 		spin_lock(&cmd->t_state_lock);
 		if (!(cmd->transport_state & CMD_T_ACTIVE)) {
 			spin_unlock(&cmd->t_state_lock);
+			spin_unlock(&sess->sess_cmd_lock);
 			continue;
 		}
 		if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {
 			spin_unlock(&cmd->t_state_lock);
+			spin_unlock(&sess->sess_cmd_lock);
 			continue;
 		}
+		cmd->transport_state |= CMD_T_ABORTED;
 		spin_unlock(&cmd->t_state_lock);
 
+		rc = kref_get_unless_zero(&cmd->cmd_kref);
+		spin_unlock(&sess->sess_cmd_lock);
+		if (!rc) {
+			printk("LUN_RESET TMR: non-zero kref_get_unless_zero\n");
+			continue;
+		}
 		list_move_tail(&tmr_p->tmr_list, &drain_tmr_list);
 	}
 	spin_unlock_irqrestore(&dev->se_tmr_lock, flags);

@@ -246,7 +262,11 @@ static void core_tmr_drain_tmr_list(
 			(preempt_and_abort_list) ? "Preempt" : "", tmr_p,
 			tmr_p->function, tmr_p->response, cmd->t_state);
 
+		cancel_work_sync(&cmd->work);
+		transport_wait_for_tasks(cmd);
+
 		transport_cmd_finish_abort(cmd, 1);
+		target_put_sess_cmd(cmd);
 	}
 }

drivers/target/target_core_transport.c +17 -0

index af52f8bd8954..94e372af9e28 100644
@@ -2900,8 +2900,17 @@ static void target_tmr_work(struct work_struct *work)
 	struct se_cmd *cmd = container_of(work, struct se_cmd, work);
 	struct se_device *dev = cmd->se_dev;
 	struct se_tmr_req *tmr = cmd->se_tmr_req;
+	unsigned long flags;
 	int ret;
 
+	spin_lock_irqsave(&cmd->t_state_lock, flags);
+	if (cmd->transport_state & CMD_T_ABORTED) {
+		tmr->response = TMR_FUNCTION_REJECTED;
+		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+		goto check_stop;
+	}
+	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
 	switch (tmr->function) {
 	case TMR_ABORT_TASK:
 		core_tmr_abort_task(dev, tmr, cmd->se_sess);

@@ -2934,9 +2943,17 @@ static void target_tmr_work(struct work_struct *work)
 		break;
 	}
 
+	spin_lock_irqsave(&cmd->t_state_lock, flags);
+	if (cmd->transport_state & CMD_T_ABORTED) {
+		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+		goto check_stop;
+	}
 	cmd->t_state = TRANSPORT_ISTATE_PROCESSING;
+	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
 	cmd->se_tfo->queue_tm_rsp(cmd);
 
+check_stop:
 	transport_cmd_check_stop_to_fabric(cmd);
 }