IB/ipath: Head of Line blocking vs forward progress of user apps
There's a conflict between our need to quiesce PSM-based applications
to avoid HoL blocking when the IB link goes down and the apps' desire
to remain running so that their quiescence timout mechanism can keep
running.
The compromise is to STOP the processes for a fixed period of time and
then alternate between CONT and STOP until the link is again active.
If there are poor interactions with subnet manager configuration at a
given site, the interval can be adjusted via a module paramter.
Signed-off-by: John Gregor <john.gregor@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_diag.c b/drivers/infiniband/hw/ipath/ipath_diag.c
index 4137c77..96a1c41 100644
--- a/drivers/infiniband/hw/ipath/ipath_diag.c
+++ b/drivers/infiniband/hw/ipath/ipath_diag.c
@@ -330,6 +330,7 @@
struct ipath_devdata *dd;
ssize_t ret = 0;
u64 val;
+ u32 l_state, lt_state; /* LinkState, LinkTrainingState */
if (count != sizeof(dp)) {
ret = -EINVAL;
@@ -396,10 +397,17 @@
ret = -ENODEV;
goto bail;
}
- /* Check link state, but not if we have custom PBC */
- val = dd->ipath_lastibcstat & IPATH_IBSTATE_MASK;
- if (!dp.pbc_wd && val != IPATH_IBSTATE_INIT &&
- val != IPATH_IBSTATE_ARM && val != IPATH_IBSTATE_ACTIVE) {
+ /*
+ * Want to skip check for l_state if using custom PBC,
+ * because we might be trying to force an SM packet out.
+ * first-cut, skip _all_ state checking in that case.
+ */
+ val = ipath_ib_state(dd, dd->ipath_lastibcstat);
+ lt_state = ipath_ib_linktrstate(dd, dd->ipath_lastibcstat);
+ l_state = ipath_ib_linkstate(dd, dd->ipath_lastibcstat);
+ if (!dp.pbc_wd && (lt_state != INFINIPATH_IBCS_LT_STATE_LINKUP ||
+ (val != dd->ib_init && val != dd->ib_arm &&
+ val != dd->ib_active))) {
ipath_cdbg(VERBOSE, "unit %u not ready (state %llx)\n",
dd->ipath_unit, (unsigned long long) val);
ret = -EINVAL;
@@ -438,6 +446,8 @@
ret = -EBUSY;
goto bail;
}
+ /* disarm it just to be extra sure */
+ ipath_disarm_piobufs(dd, pbufn, 1);
plen >>= 2; /* in dwords */
