commit: fd3a9025c0349bc9b01d627529f54e6e1e389015
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date: Wed, 27 Feb 2013 17:53:52 -0800
Subject: iscsi-target: Fix immediate queue starvation regression with DATAIN
This patch addresses a v3.5+ regression in iscsi-target where TX thread
process context -> handle_response_queue() execution is allowed to run
unbounded while servicing constant outgoing flow of ISTATE_SEND_DATAIN
response state.
This ends up preventing memory release of StatSN acknowledged commands
in a timely manner when under heavy large block streaming DATAIN
workloads.
The regression bug was initially introduced with:
commit 6f3c0e69a9c20441bdc6d3b2d18b83b244384ec6
Author: Andy Grover <agrover@xxxxxxxxxx>
Date: Tue Apr 3 15:51:09 2012 -0700
target/iscsi: Refactor target_tx_thread immediate+response queue loops
Go ahead and follow original iscsi_target_tx_thread() logic and check
to break for immediate queue processing after each DataIN Sequence and/or
Response PDU has been sent.
Reported-by: Benjamin ESTRABAUD <be@xxxxxxxxxx>
Cc: Andy Grover <agrover@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/iscsi/iscsi_target.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 23a98e6..af77396 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -3583,6 +3583,10 @@ check_rsp_state:
spin_lock_bh(&cmd->istate_lock);
cmd->i_state = ISTATE_SENT_STATUS;
spin_unlock_bh(&cmd->istate_lock);
+
+ if (atomic_read(&conn->check_immediate_queue))
+ return 1;
+
continue;
} else if (ret == 2) {
/* Still must send status,
@@ -3672,7 +3676,7 @@ check_rsp_state:
}
if (atomic_read(&conn->check_immediate_queue))
- break;
+ return 1;
}
return 0;
@@ -3716,12 +3720,15 @@ restart:
signal_pending(current))
goto transport_err;
+get_immediate:
ret = handle_immediate_queue(conn);
if (ret < 0)
goto transport_err;
ret = handle_response_queue(conn);
- if (ret == -EAGAIN)
+ if (ret == 1)
+ goto get_immediate;
+ else if (ret == -EAGAIN)
goto restart;
else if (ret < 0)
goto transport_err;
--
1.7.10.4
--
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