The conn_send_pdu API is evil in that it returns a pointer to a
iscsi_task, but that task might have been freed already so you can't
touch it. This patch splits the task allocation and transmission, so
functions like iscsi_send_nopout can access the task before its sent and
do whatever book keeping is needed before it's sent.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/scsi/libiscsi.c | 85 ++++++++++++++++++++++++++++++-----------
include/scsi/libiscsi.h | 3 --
2 files changed, 62 insertions(+), 26 deletions(-)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index cde389225059..a165d4d10cea 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -695,12 +695,18 @@ static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
return 0;
}
+/**
+ * iscsi_alloc_mgmt_task - allocate and setup a mgmt task.
+ * @conn: iscsi conn that the task will be sent on.
+ * @hdr: iscsi pdu that will be sent.
+ * @data: buffer for data segment if needed.
+ * @data_size: length of data in bytes.
+ */
static struct iscsi_task *
-__iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
+iscsi_alloc_mgmt_task(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
char *data, uint32_t data_size)
{
struct iscsi_session *session = conn->session;
- struct iscsi_host *ihost = shost_priv(session->host);
uint8_t opcode = hdr->opcode & ISCSI_OPCODE_MASK;
struct iscsi_task *task;
itt_t itt;
@@ -780,28 +786,57 @@ __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);
+ return task;
+
+free_task:
+ iscsi_put_task(task);
+ return NULL;
+}
+
+/**
+ * iscsi_send_mgmt_task - Send task created with iscsi_alloc_mgmt_task.
+ * @task: iscsi task to send.
+ *
+ * On failure this returns a non-zero error code, and the driver must free
+ * the task with iscsi_put_task;
+ */
+static int iscsi_send_mgmt_task(struct iscsi_task *task)
+{
+ struct iscsi_conn *conn = task->conn;
+ struct iscsi_session *session = conn->session;
+ struct iscsi_host *ihost = shost_priv(conn->session->host);
+ int rc = 0;
if (!ihost->workq) {
- if (iscsi_prep_mgmt_task(conn, task))
- goto free_task;
+ rc = iscsi_prep_mgmt_task(conn, task);
+ if (rc)
+ return rc;
- if (session->tt->xmit_task(task))
- goto free_task;
+ rc = session->tt->xmit_task(task);
+ if (rc)
+ return rc;
} else {
list_add_tail(&task->running, &conn->mgmtqueue);
iscsi_conn_queue_xmit(conn);
}
- return task;
+ return 0;
+}
-free_task:
- /* regular RX path uses back_lock */
- spin_lock(&session->back_lock);
- __iscsi_put_task(task);
- spin_unlock(&session->back_lock);
- return NULL;
+static int __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
+ char *data, uint32_t data_size)
+{
+ struct iscsi_task *task;
+ int rc;
+
+ task = iscsi_alloc_mgmt_task(conn, hdr, data, data_size);
+ if (!task)
+ return -ENOMEM;
+
+ rc = iscsi_send_mgmt_task(task);
+ if (rc)
+ iscsi_put_task(task);
+ return rc;
}
int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
@@ -812,7 +847,7 @@ int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
int err = 0;
spin_lock_bh(&session->frwd_lock);
- if (!__iscsi_conn_send_pdu(conn, hdr, data, data_size))
+ if (__iscsi_conn_send_pdu(conn, hdr, data, data_size))
err = -EPERM;
spin_unlock_bh(&session->frwd_lock);
return err;
@@ -985,7 +1020,6 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
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));
@@ -999,10 +1033,18 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
} else
hdr.ttt = RESERVED_ITT;
- task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
- if (!task) {
+ task = iscsi_alloc_mgmt_task(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
+ if (!task)
+ return -ENOMEM;
+
+ if (!rhdr)
+ WRITE_ONCE(conn->ping_task, task);
+
+ if (iscsi_send_mgmt_task(task)) {
if (!rhdr)
WRITE_ONCE(conn->ping_task, NULL);
+ iscsi_put_task(task);
+
iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n");
return -EIO;
} else if (!rhdr) {
@@ -1869,11 +1911,8 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
__must_hold(&session->frwd_lock)
{
struct iscsi_session *session = conn->session;
- struct iscsi_task *task;
- task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr,
- NULL, 0);
- if (!task) {
+ if (__iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr, NULL, 0)) {
spin_unlock_bh(&session->frwd_lock);
iscsi_conn_printk(KERN_ERR, conn, "Could not send TMF.\n");
iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 9032a214104c..412722f44747 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -134,9 +134,6 @@ 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;
