[PATCH v6 14/33] target: Avoid that target drivers hang if a command is aborted

From: Bart Van Assche <bart.vanassche@sandisk.com>
To: "Nicholas A . Bellinger" <nab@linux-iscsi.org>
Cc: <target-devel@vger.kernel.org>,
	Bart Van Assche <bart.vanassche@sandisk.com>,
	<stable@vger.kernel.org>
Subject: [PATCH v6 14/33] target: Avoid that target drivers hang if a command is aborted
Date: Tue, 14 Feb 2017 16:25:53 -0800	[thread overview]
Message-ID: <20170215002612.14566-15-bart.vanassche@sandisk.com> (raw)
In-Reply-To: <20170215002612.14566-1-bart.vanassche@sandisk.com>

For several target drivers (e.g. ib_srpt and ib_isert) sleeping inside
transport_generic_free_cmd() causes RDMA completion processing to stall.
Hence only sleep inside this function if the (iSCSI) target driver
requires this.

This patch avoids that messages similar to the following appear in the
kernel log:

INFO: task kworker/u25:0:1013 blocked for more than 480 seconds.
      Tainted: G        W       4.10.0-rc7-dbg+ #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u25:0   D    0  1013      2 0x00000000
Workqueue: ib-comp-wq ib_cq_poll_work [ib_core]
Call Trace:
 __schedule+0x2da/0xb00
 schedule+0x38/0x90
 schedule_timeout+0x2fe/0x640
 wait_for_completion+0xfe/0x160
 transport_generic_free_cmd+0x2e/0x80 [target_core_mod]
 srpt_send_done+0x59/0x9f [ib_srpt]
 __ib_process_cq+0x4b/0xd0 [ib_core]
 ib_cq_poll_work+0x1b/0x60 [ib_core]
 process_one_work+0x208/0x6a0
 worker_thread+0x49/0x4a0
 kthread+0x107/0x140
 ret_from_fork+0x2e/0x40

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: <stable@vger.kernel.org>
---
 drivers/target/target_core_transport.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 2ed9721a7202..ab1c493a9a16 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2504,15 +2504,13 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
 	int ret = 0;
 	bool aborted = false, tas = false;
 
-	if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) {
-		if (wait_for_tasks && (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
-			target_wait_free_cmd(cmd, &aborted, &tas);
+	if (wait_for_tasks)
+		target_wait_free_cmd(cmd, &aborted, &tas);
 
+	if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) {
 		if (!aborted || tas)
 			ret = transport_put_cmd(cmd);
 	} else {
-		if (wait_for_tasks)
-			target_wait_free_cmd(cmd, &aborted, &tas);
 		/*
 		 * Handle WRITE failure case where transport_generic_new_cmd()
 		 * has already added se_cmd to state_list, but fabric has
@@ -2535,7 +2533,6 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
 	 */
 	if (aborted) {
 		pr_debug("Detected CMD_T_ABORTED for ITT: %llu\n", cmd->tag);
-		wait_for_completion(&cmd->cmd_wait_comp);
 		cmd->se_tfo->release_cmd(cmd);
 		ret = 1;
 	}
-- 
2.11.0
