linux-kernel - [074/146] [SCSI] target: Fix bug with task

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Date:	Wed, 01 Jun 2011 17:00:10 +0900
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Nicholas Bellinger <nab@...ux-iscsi.org>,
	James Bottomley <jbottomley@...allels.com>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [074/146] [SCSI] target: Fix bug with task_sg chained

2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------
 transport_free_dev_tasks release

From: Nicholas Bellinger <nab@...ux-iscsi.org>

commit f436677262a5b524ac87675014c6d4e8ee153029 upstream.

This patch addresses a bug in the target core release path for HW
operation where transport_free_dev_tasks() was incorrectly being called
from transport_lun_remove_cmd() while releasing a se_cmd reference and
calling struct target_core_fabric_ops->queue_data_in().

This would result in a OOPs with HW target mode when the release of
se_task->task_sg[] would happen before pci_unmap_sg() can be called in
HW target mode fabric module code.  This patch addresses the issue by
moving transport_free_dev_tasks() from transport_lun_remove_cmd() into
transport_generic_free_cmd(), and adding TRANSPORT_FREE_CMD_INTR and
transport_generic_free_cmd_intr() to allow se_cmd descriptor release
to happen fromfrom within transport_processing_thread() process context
when release of se_cmd is not possible from HW interrupt context.

Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: James Bottomley <jbottomley@...allels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/target/target_core_transport.c |   13 ++++++++++++-
 include/target/target_core_base.h      |    1 +
 include/target/target_core_transport.h |    1 +
 3 files changed, 14 insertions(+), 1 deletion(-)

--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -765,7 +765,6 @@ static void transport_lun_remove_cmd(str
 	transport_all_task_dev_remove_state(cmd);
 	spin_unlock_irqrestore(&T_TASK(cmd)->t_state_lock, flags);
 
-	transport_free_dev_tasks(cmd);
 
 check_lun:
 	spin_lock_irqsave(&lun->lun_cmd_lock, flags);
@@ -2062,6 +2061,13 @@ int transport_generic_handle_tmr(
 }
 EXPORT_SYMBOL(transport_generic_handle_tmr);
 
+void transport_generic_free_cmd_intr(
+	struct se_cmd *cmd)
+{
+	transport_add_cmd_to_queue(cmd, TRANSPORT_FREE_CMD_INTR);
+}
+EXPORT_SYMBOL(transport_generic_free_cmd_intr);
+
 static int transport_stop_tasks_for_cmd(struct se_cmd *cmd)
 {
 	struct se_task *task, *task_tmp;
@@ -5302,6 +5308,8 @@ void transport_generic_free_cmd(
 		if (wait_for_tasks && cmd->transport_wait_for_tasks)
 			cmd->transport_wait_for_tasks(cmd, 0, 0);
 
+		transport_free_dev_tasks(cmd);
+
 		transport_generic_remove(cmd, release_to_pool,
 				session_reinstatement);
 	}
@@ -6142,6 +6150,9 @@ get_cmd:
 		case TRANSPORT_REMOVE:
 			transport_generic_remove(cmd, 1, 0);
 			break;
+		case TRANSPORT_FREE_CMD_INTR:
+			transport_generic_free_cmd(cmd, 0, 1, 0);
+			break;
 		case TRANSPORT_PROCESS_TMR:
 			transport_generic_do_tmr(cmd);
 			break;
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -98,6 +98,7 @@ enum transport_state_table {
 	TRANSPORT_REMOVE	= 14,
 	TRANSPORT_FREE		= 15,
 	TRANSPORT_NEW_CMD_MAP	= 16,
+	TRANSPORT_FREE_CMD_INTR = 17,
 };
 
 /* Used for struct se_cmd->se_cmd_flags */
--- a/include/target/target_core_transport.h
+++ b/include/target/target_core_transport.h
@@ -170,6 +170,7 @@ extern int transport_generic_handle_cdb_
 extern int transport_generic_handle_data(struct se_cmd *);
 extern void transport_new_cmd_failure(struct se_cmd *);
 extern int transport_generic_handle_tmr(struct se_cmd *);
+extern void transport_generic_free_cmd_intr(struct se_cmd *);
 extern void __transport_stop_task_timer(struct se_task *, unsigned long *);
 extern unsigned char transport_asciihex_to_binaryhex(unsigned char val[2]);
 extern int transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *, u32,


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