[PATCH] target: Fix se_cmd->state_list leak regression during WRITE failure

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Nicholas A. Bellinger

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Aug 31, 2013, 6:40:07 PM8/31/13
to target-devel, Nicholas Bellinger
From: Nicholas Bellinger <n...@linux-iscsi.org>

This patch addresses a v3.11 specific regression where se_cmd->state_list
was being leaked during a fabric WRITE failure, when the fabric releases
an associated se_cmd descriptor before I/O submission occurs, and normal
fast path callbacks have a chance to call target_remove_from_state_list().

It was manifesting with Poison overwritten messages with iscsi-target
once an ImmediateData payload CRC32C failure occured.

This bug was originally introduced during v3.11-rc1 with the following
commit:

commit 0b66818ac6de67a6125ae203272fb76e79b3a20f
Author: Nicholas Bellinger <n...@linux-iscsi.org>
Date: Thu Jun 6 01:36:41 2013 -0700

target: Drop unnecessary CMD_T_DEV_ACTIVE check from transport_lun_remove_cmd

Signed-off-by: Nicholas Bellinger <n...@linux-iscsi.org>
---
drivers/target/target_core_transport.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 7172d00..d8e49d7 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2134,6 +2134,7 @@ static void transport_write_pending_qf(struct se_cmd *cmd)

int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
{
+ unsigned long flags;
int ret = 0;

if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) {
@@ -2144,6 +2145,16 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
} else {
if (wait_for_tasks)
transport_wait_for_tasks(cmd);
+ /*
+ * Handle WRITE failure case where transport_generic_new_cmd()
+ * has already added se_cmd to state_list, but fabric has
+ * failed command before I/O submission.
+ */
+ if (cmd->state_active) {
+ spin_lock_irqsave(&cmd->t_state_lock, flags);
+ target_remove_from_state_list(cmd);
+ spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+ }

if (cmd->se_lun)
transport_lun_remove_cmd(cmd);
--
1.7.2.5

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