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authorLee Duncan <lduncan@suse.com>2020-11-06 11:33:17 -0800
committerMartin K. Petersen <martin.petersen@oracle.com>2020-11-16 22:32:50 -0500
commitfe0a8a95e7134d0b44cd407bc0085b9ba8d8fe31 (patch)
treedb4b4dc891d17476e89cc1b9194406a9bd325357 /drivers/scsi
parent2e6f11a797a24d1e2141a214a6dd6dfbe709f55d (diff)
downloadlinux-fe0a8a95e7134d0b44cd407bc0085b9ba8d8fe31.tar.bz2
scsi: libiscsi: Fix NOP race condition
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>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/libiscsi.c23
1 files changed, 15 insertions, 8 deletions
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 1e9c3171fa9f..f9314f1393fb 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -533,8 +533,8 @@ 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);
@@ -738,6 +738,9 @@ __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;
@@ -941,8 +944,11 @@ 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;
@@ -957,11 +963,12 @@ 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;
}
@@ -984,7 +991,7 @@ 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.
@@ -1923,7 +1930,7 @@ 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;
@@ -2058,7 +2065,7 @@ 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;