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scsi: libiscsi: Improve conn_send_pdu API 

The conn_send_pdu API is evil in that it returns a pointer to an
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 bookkeeping is needed before it is sent.

Link: https://lore.kernel.org/r/20220616224557.115234-10-michael.christie@oracle.com
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Mike Christie 2022-06-16 17:45:57 -05:00 committed by Martin K. Petersen
parent 6d626150d6
commit 6e637b723d
2 changed files with 62 additions and 26 deletions
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85
drivers/scsi/libiscsi.c
View File

@ -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;
@ -781,28 +787,57 @@ __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,
@ -813,7 +848,7 @@ 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;
@ -986,7 +1021,6 @@ 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));
@ -1000,10 +1034,18 @@ 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) {
@ -1874,11 +1916,8 @@ 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);

3
include/scsi/libiscsi.h
View File

@ -135,9 +135,6 @@ 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;