git: 444aff36738a - stable/13 - cam: Permit non-pollable sims.

[John Baldwin]

The branch stable/13 has been updated by jhb:

URL: https://cgit.FreeBSD.org/src/commit/?id=444aff36738a98235306aa002d3dfe74cc475765

commit 444aff36738a98235306aa002d3dfe74cc475765
Author:     John Baldwin <jhb at FreeBSD.org>
AuthorDate: 2021-02-11 21:49:43 +0000
Commit:     John Baldwin <jhb at FreeBSD.org>
CommitDate: 2021-03-22 20:36:09 +0000

    cam: Permit non-pollable sims.
    
    Some CAM sim drivers do not support polling (notably iscsi(4)).
    Rather than using a no-op poll routine that always times out requests,
    permit a SIM to set a NULL poll callback.  cam_periph_runccb() will
    fail polled requests non-pollable sims immediately as if they had
    timed out.
    
    Sponsored by:   Chelsio
    
    (cherry picked from commit 447b3557a9cc5f00a301be8404339f21a9a0faa8)
    (cherry picked from commit e6405c8c37335a42a187a9d2470025b57347b1b5)
---
 sys/cam/cam_periph.c | 6 +++++-
 sys/cam/cam_sim.h    | 6 ++++++
 sys/cam/cam_xpt.c    | 5 +++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/sys/cam/cam_periph.c b/sys/cam/cam_periph.c
index 92f7c33cbc75..98b9264f1069 100644
--- a/sys/cam/cam_periph.c
+++ b/sys/cam/cam_periph.c
@@ -54,6 +54,7 @@ __FBSDID("$FreeBSD$");
 #include <cam/cam_ccb.h>
 #include <cam/cam_queue.h>
 #include <cam/cam_xpt_periph.h>
+#include <cam/cam_xpt_internal.h>
 #include <cam/cam_periph.h>
 #include <cam/cam_debug.h>
 #include <cam/cam_sim.h>
@@ -1247,7 +1248,10 @@ cam_periph_runccb(union ccb *ccb,
 	 * in the do loop below.
 	 */
 	if (must_poll) {
-		timeout = xpt_poll_setup(ccb);
+		if (cam_sim_pollable(ccb->ccb_h.path->bus->sim))
+			timeout = xpt_poll_setup(ccb);
+		else
+			timeout = 0;
 	}
 
 	if (timeout == 0) {
diff --git a/sys/cam/cam_sim.h b/sys/cam/cam_sim.h
index 589d2bd1f16d..a1595a51fadb 100644
--- a/sys/cam/cam_sim.h
+++ b/sys/cam/cam_sim.h
@@ -142,5 +142,11 @@ cam_sim_bus(const struct cam_sim *sim)
 	return (sim->bus_id);
 }
 
+static __inline bool
+cam_sim_pollable(const struct cam_sim *sim)
+{
+	return (sim->sim_poll != NULL);
+}
+
 #endif /* _KERNEL */
 #endif /* _CAM_CAM_SIM_H */
diff --git a/sys/cam/cam_xpt.c b/sys/cam/cam_xpt.c
index d71b8ef81240..9cfee80a6049 100644
--- a/sys/cam/cam_xpt.c
+++ b/sys/cam/cam_xpt.c
@@ -3181,6 +3181,7 @@ xpt_sim_poll(struct cam_sim *sim)
 {
 	struct mtx *mtx;
 
+	KASSERT(cam_sim_pollable(sim), ("%s: non-pollable sim", __func__));
 	mtx = sim->mtx;
 	if (mtx)
 		mtx_lock(mtx);
@@ -3203,6 +3204,8 @@ xpt_poll_setup(union ccb *start_ccb)
 	devq = sim->devq;
 	dev = start_ccb->ccb_h.path->device;
 
+	KASSERT(cam_sim_pollable(sim), ("%s: non-pollable sim", __func__));
+
 	/*
 	 * Steal an opening so that no other queued requests
 	 * can get it before us while we simulate interrupts.
@@ -3226,6 +3229,8 @@ void
 xpt_pollwait(union ccb *start_ccb, uint32_t timeout)
 {
 
+	KASSERT(cam_sim_pollable(start_ccb->ccb_h.path->bus->sim),
+	    ("%s: non-pollable sim", __func__));
 	while (--timeout > 0) {
 		xpt_sim_poll(start_ccb->ccb_h.path->bus->sim);
 		if ((start_ccb->ccb_h.status & CAM_STATUS_MASK)