[SCSI] libiscsi: fix cmds_max setting
Drivers expect that the cmds_max value they pass to the iscsi layer
is the max scsi commands + mgmt tasks. This patch implements that
and fixes some checks for nr cmd limits.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index c1af2aa..c723e60 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -1893,29 +1893,48 @@
*
* This can be used by software iscsi_transports that allocate
* a session per scsi host.
+ *
+ * Callers should set cmds_max to the largest total numer (mgmt + scsi) of
+ * tasks they support. The iscsi layer reserves ISCSI_MGMT_CMDS_MAX tasks
+ * for nop handling and login/logout requests.
*/
struct iscsi_cls_session *
iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
- uint16_t scsi_cmds_max, int cmd_task_size,
+ uint16_t cmds_max, int cmd_task_size,
uint32_t initial_cmdsn, unsigned int id)
{
struct iscsi_session *session;
struct iscsi_cls_session *cls_session;
- int cmd_i, cmds_max;
-
+ int cmd_i, scsi_cmds, total_cmds = cmds_max;
/*
- * The iscsi layer needs some tasks for nop handling and tmfs.
+ * The iscsi layer needs some tasks for nop handling and tmfs,
+ * so the cmds_max must at least be greater than ISCSI_MGMT_CMDS_MAX
+ * + 1 command for scsi IO.
*/
- if (scsi_cmds_max < 1)
- scsi_cmds_max = ISCSI_MGMT_CMDS_MAX;
- if ((scsi_cmds_max + ISCSI_MGMT_CMDS_MAX) >= ISCSI_MGMT_ITT_OFFSET) {
- printk(KERN_ERR "iscsi: invalid can_queue of %d. "
- "can_queue must be less than %d.\n",
- scsi_cmds_max,
- ISCSI_MGMT_ITT_OFFSET - ISCSI_MGMT_CMDS_MAX);
- scsi_cmds_max = ISCSI_DEF_XMIT_CMDS_MAX;
+ if (total_cmds < ISCSI_TOTAL_CMDS_MIN) {
+ printk(KERN_ERR "iscsi: invalid can_queue of %d. can_queue "
+ "must be a power of two that is at least %d.\n",
+ total_cmds, ISCSI_TOTAL_CMDS_MIN);
+ return NULL;
}
- cmds_max = roundup_pow_of_two(scsi_cmds_max + ISCSI_MGMT_CMDS_MAX);
+
+ if (total_cmds > ISCSI_TOTAL_CMDS_MAX) {
+ printk(KERN_ERR "iscsi: invalid can_queue of %d. can_queue "
+ "must be a power of 2 less than or equal to %d.\n",
+ cmds_max, ISCSI_TOTAL_CMDS_MAX);
+ total_cmds = ISCSI_TOTAL_CMDS_MAX;
+ }
+
+ if (!is_power_of_2(total_cmds)) {
+ printk(KERN_ERR "iscsi: invalid can_queue of %d. can_queue "
+ "must be a power of 2.\n", total_cmds);
+ total_cmds = rounddown_pow_of_two(total_cmds);
+ if (total_cmds < ISCSI_TOTAL_CMDS_MIN)
+ return NULL;
+ printk(KERN_INFO "iscsi: Rounding can_queue to %d.\n",
+ total_cmds);
+ }
+ scsi_cmds = total_cmds - ISCSI_MGMT_CMDS_MAX;
cls_session = iscsi_alloc_session(shost, iscsit,
sizeof(struct iscsi_session));
@@ -1928,8 +1947,8 @@
session->fast_abort = 1;
session->lu_reset_timeout = 15;
session->abort_timeout = 10;
- session->scsi_cmds_max = scsi_cmds_max;
- session->cmds_max = cmds_max;
+ session->scsi_cmds_max = scsi_cmds;
+ session->cmds_max = total_cmds;
session->queued_cmdsn = session->cmdsn = initial_cmdsn;
session->exp_cmdsn = initial_cmdsn + 1;
session->max_cmdsn = initial_cmdsn + 1;