From: Lee Duncan lduncan@suse.com
[ Upstream commit fe0a8a95e7134d0b44cd407bc0085b9ba8d8fe31 ]
iSCSI NOPs are sometimes "lost", mistakenly sent to the user-land iscsid daemon instead of handled in the kernel, as they should be, resulting in a message from the daemon like:
iscsid: Got nop in, but kernel supports nop handling.
This can occur because of the new forward- and back-locks, and the fact that an iSCSI NOP response can occur before processing of the NOP send is complete. This can result in "conn->ping_task" being NULL in iscsi_nop_out_rsp(), when the pointer is actually in the process of being set.
To work around this, we add a new state to the "ping_task" pointer. In addition to NULL (not assigned) and a pointer (assigned), we add the state "being set", which is signaled with an INVALID pointer (using "-1").
Link: https://lore.kernel.org/r/20201106193317.16993-1-leeman.duncan@gmail.com Reviewed-by: Mike Christie michael.christie@oracle.com Signed-off-by: Lee Duncan lduncan@suse.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/libiscsi.c | 23 +++++++++++++++-------- include/scsi/libiscsi.h | 3 +++ 2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c index ec356e035c5f..9a4a4f154bc6 100644 --- a/drivers/scsi/libiscsi.c +++ b/drivers/scsi/libiscsi.c @@ -577,8 +577,8 @@ static void iscsi_complete_task(struct iscsi_task *task, int state) if (conn->task == task) conn->task = NULL;
- if (conn->ping_task == task) - conn->ping_task = NULL; + if (READ_ONCE(conn->ping_task) == task) + WRITE_ONCE(conn->ping_task, NULL);
/* release get from queueing */ __iscsi_put_task(task); @@ -787,6 +787,9 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr, task->conn->session->age); }
+ if (unlikely(READ_ONCE(conn->ping_task) == INVALID_SCSI_TASK)) + WRITE_ONCE(conn->ping_task, task); + if (!ihost->workq) { if (iscsi_prep_mgmt_task(conn, task)) goto free_task; @@ -997,8 +1000,11 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr) struct iscsi_nopout hdr; struct iscsi_task *task;
- if (!rhdr && conn->ping_task) - return -EINVAL; + if (!rhdr) { + if (READ_ONCE(conn->ping_task)) + return -EINVAL; + WRITE_ONCE(conn->ping_task, INVALID_SCSI_TASK); + }
memset(&hdr, 0, sizeof(struct iscsi_nopout)); hdr.opcode = ISCSI_OP_NOOP_OUT | ISCSI_OP_IMMEDIATE; @@ -1013,11 +1019,12 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0); if (!task) { + if (!rhdr) + WRITE_ONCE(conn->ping_task, NULL); iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n"); return -EIO; } else if (!rhdr) { /* only track our nops */ - conn->ping_task = task; conn->last_ping = jiffies; }
@@ -1040,7 +1047,7 @@ static int iscsi_nop_out_rsp(struct iscsi_task *task, struct iscsi_conn *conn = task->conn; int rc = 0;
- if (conn->ping_task != task) { + if (READ_ONCE(conn->ping_task) != task) { /* * If this is not in response to one of our * nops then it must be from userspace. @@ -1984,7 +1991,7 @@ static void iscsi_start_tx(struct iscsi_conn *conn) */ static int iscsi_has_ping_timed_out(struct iscsi_conn *conn) { - if (conn->ping_task && + if (READ_ONCE(conn->ping_task) && time_before_eq(conn->last_recv + (conn->recv_timeout * HZ) + (conn->ping_timeout * HZ), jiffies)) return 1; @@ -2119,7 +2126,7 @@ enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc) * Checking the transport already or nop from a cmd timeout still * running */ - if (conn->ping_task) { + if (READ_ONCE(conn->ping_task)) { task->have_checked_conn = true; rc = BLK_EH_RESET_TIMER; goto done; diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h index e03b9244499e..8e146aa623cf 100644 --- a/include/scsi/libiscsi.h +++ b/include/scsi/libiscsi.h @@ -145,6 +145,9 @@ struct iscsi_task { void *dd_data; /* driver/transport data */ };
+/* invalid scsi_task pointer */ +#define INVALID_SCSI_TASK (struct iscsi_task *)-1l + static inline int iscsi_task_has_unsol_data(struct iscsi_task *task) { return task->unsol_r2t.data_length > task->unsol_r2t.sent;