[SCSI] target: Fix bug with task_sg chained transport_free_dev_tasks release

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@linux-iscsi.org>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <jbottomley@parallels.com>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 1d3b5b2f0dbc..561ac99def5a 100644
--- 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 */
diff --git a/include/target/target_core_transport.h b/include/target/target_core_transport.h
index 59aa464f6ee2..24a1c6cb83c3 100644
--- a/include/target/target_core_transport.h
+++ b/include/target/target_core_transport.h
@@ -172,6 +172,7 @@ extern int transport_generic_handle_cdb_map(struct se_cmd *);
 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,