| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 048/173] iscsi-target: Fix mutex_trylock usage in iscsit_increment_maxcmdsn | Date | Mon, 2 Dec 2013 11:10:31 -0800 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: Nicholas Bellinger <nab@linux-iscsi.org>
commit 5e8e6b4b3adebf01a9d97056cbbfd8c44330df99 upstream.
This patch fixes a >= v3.10 regression bug with mutex_trylock() usage within iscsit_increment_maxcmdsn(), that was originally added to allow for a special case where ->cmdsn_mutex was already held from the iscsit_execute_cmd() exception path for ib_isert.
When !mutex_trylock() was occuring under contention during normal RX/TX process context codepaths, the bug was manifesting itself as the following protocol error:
Received CmdSN: 0x000fcbb7 is greater than MaxCmdSN: 0x000fcbb6, protocol error. Received CmdSN: 0x000fcbb8 is greater than MaxCmdSN: 0x000fcbb6, protocol error.
This patch simply avoids the direct ib_isert callback in lio_queue_status() for the special iscsi_execute_cmd() exception cases, that allows the problematic mutex_trylock() usage in iscsit_increment_maxcmdsn() to go away.
Reported-by: Moussa Ba <moussaba@micron.com> Tested-by: Moussa Ba <moussaba@micron.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/target/iscsi/iscsi_target_configfs.c | 5 +++++ drivers/target/iscsi/iscsi_target_device.c | 6 +----- 2 files changed, 6 insertions(+), 5 deletions(-)
--- a/drivers/target/iscsi/iscsi_target_configfs.c +++ b/drivers/target/iscsi/iscsi_target_configfs.c @@ -1650,6 +1650,11 @@ static int lio_queue_status(struct se_cm struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd); cmd->i_state = ISTATE_SEND_STATUS; + + if (cmd->se_cmd.scsi_status || cmd->sense_reason) { + iscsit_add_cmd_to_response_queue(cmd, cmd->conn, cmd->i_state); + return 0; + } cmd->conn->conn_transport->iscsit_queue_status(cmd->conn, cmd); return 0; --- a/drivers/target/iscsi/iscsi_target_device.c +++ b/drivers/target/iscsi/iscsi_target_device.c @@ -60,11 +60,7 @@ void iscsit_increment_maxcmdsn(struct is cmd->maxcmdsn_inc = 1; - if (!mutex_trylock(&sess->cmdsn_mutex)) { - sess->max_cmd_sn += 1; - pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn); - return; - } + mutex_lock(&sess->cmdsn_mutex); sess->max_cmd_sn += 1; pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn); mutex_unlock(&sess->cmdsn_mutex);
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