Module Name: src
Committed By: jdolecek
Date: Tue Apr 14 13:10:43 UTC 2020
Modified Files:
src/sys/arch/xen/xen: xbd_xenbus.c
Log Message:
use single pre-allocated buffer for unaligned I/O - it's rare and not
performance critical path, it's more important to ensure it will succeed
eventually; also return EAGAIN rather than ENOMEM, so the I/O will be
retried by dk_start() when previous I/O finishes
fix yet another leak on the xengnt_grant_access() fail path in
xbd_diskstart() - this time the unalign buffer
To generate a diff of this commit:
cvs rdiff -u -r1.110 -r1.111 src/sys/arch/xen/xen/xbd_xenbus.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/xen/xen/xbd_xenbus.c
diff -u src/sys/arch/xen/xen/xbd_xenbus.c:1.110 src/sys/arch/xen/xen/xbd_xenbus.c:1.111
--- src/sys/arch/xen/xen/xbd_xenbus.c:1.110 Tue Apr 14 13:02:40 2020
+++ src/sys/arch/xen/xen/xbd_xenbus.c Tue Apr 14 13:10:43 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: xbd_xenbus.c,v 1.110 2020/04/14 13:02:40 jdolecek Exp $ */
+/* $NetBSD: xbd_xenbus.c,v 1.111 2020/04/14 13:10:43 jdolecek Exp $ */
/*
* Copyright (c) 2006 Manuel Bouyer.
@@ -50,7 +50,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xbd_xenbus.c,v 1.110 2020/04/14 13:02:40 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xbd_xenbus.c,v 1.111 2020/04/14 13:10:43 jdolecek Exp $");
#include "opt_xen.h"
@@ -137,6 +137,9 @@ struct xbd_xenbus_softc {
struct xbd_req sc_reqs[XBD_RING_SIZE];
SLIST_HEAD(,xbd_req) sc_xbdreq_head; /* list of free requests */
+ vmem_addr_t sc_unalign_buffer;
+ bool sc_unalign_free;
+
int sc_backend_status; /* our status with backend */
#define BLKIF_STATE_DISCONNECTED 0
#define BLKIF_STATE_CONNECTED 1
@@ -159,6 +162,8 @@ struct xbd_xenbus_softc {
#define BLKIF_FEATURE_BITS \
"\20\1CACHE-FLUSH\2BARRIER\3PERSISTENT"
struct evcnt sc_cnt_map_unalign;
+ struct evcnt sc_cnt_unalign_busy;
+ struct evcnt sc_cnt_queue_full;
};
#if 0
@@ -180,8 +185,8 @@ static void xbd_iosize(device_t, int *);
static void xbd_backend_changed(void *, XenbusState);
static void xbd_connect(struct xbd_xenbus_softc *);
-static int xbd_map_align(struct xbd_req *);
-static void xbd_unmap_align(struct xbd_req *);
+static int xbd_map_align(struct xbd_xenbus_softc *, struct xbd_req *);
+static void xbd_unmap_align(struct xbd_xenbus_softc *, struct xbd_req *, bool);
static void xbdminphys(struct buf *);
@@ -297,6 +302,10 @@ xbd_xenbus_attach(device_t parent, devic
evcnt_attach_dynamic(&sc->sc_cnt_map_unalign, EVCNT_TYPE_MISC,
NULL, device_xname(self), "map unaligned");
+ evcnt_attach_dynamic(&sc->sc_cnt_unalign_busy, EVCNT_TYPE_MISC,
+ NULL, device_xname(self), "map unaligned");
+ evcnt_attach_dynamic(&sc->sc_cnt_queue_full, EVCNT_TYPE_MISC,
+ NULL, device_xname(self), "queue full");
for (i = 0; i < XBD_RING_SIZE; i++) {
if (bus_dmamap_create(sc->sc_xbusd->xbusd_dmat,
@@ -308,6 +317,13 @@ xbd_xenbus_attach(device_t parent, devic
}
}
+ if (uvm_km_kmem_alloc(kmem_va_arena,
+ MAXPHYS, VM_SLEEP | VM_INSTANTFIT, &sc->sc_unalign_buffer) != 0) {
+ aprint_error_dev(self, "can't alloc align buffer\n");
+ return;
+ }
+ sc->sc_unalign_free = true;
+
/* resume shared structures and tell backend that we are ready */
if (xbd_xenbus_resume(self, PMF_Q_NONE) == false) {
uvm_km_free(kernel_map, (vaddr_t)ring, PAGE_SIZE,
@@ -407,9 +423,16 @@ xbd_xenbus_detach(device_t dev, int flag
}
}
+ if (sc->sc_unalign_buffer != 0) {
+ uvm_km_kmem_free(kmem_va_arena, sc->sc_unalign_buffer, MAXPHYS);
+ sc->sc_unalign_buffer = 0;
+ }
+
mutex_destroy(&sc->sc_lock);
evcnt_detach(&sc->sc_cnt_map_unalign);
+ evcnt_detach(&sc->sc_cnt_unalign_busy);
+ evcnt_detach(&sc->sc_cnt_queue_full);
pmf_device_deregister(dev);
@@ -740,7 +763,7 @@ again:
bp, (long)bp->b_bcount));
if (__predict_false(bp->b_data != xbdreq->req_data))
- xbd_unmap_align(xbdreq);
+ xbd_unmap_align(sc, xbdreq, true);
xbdreq->req_bp = xbdreq->req_data = NULL;
/* b_resid was set in dk_start, only override on error */
@@ -1005,6 +1028,7 @@ xbd_diskstart(device_t self, struct buf
xbdreq = SLIST_FIRST(&sc->sc_xbdreq_head);
if (__predict_false(xbdreq == NULL)) {
+ sc->sc_cnt_queue_full.ev_count++;
DPRINTF(("xbd_diskstart: no req\n"));
error = EAGAIN;
goto out;
@@ -1018,7 +1042,7 @@ xbd_diskstart(device_t self, struct buf
sc->sc_cnt_map_unalign.ev_count++;
- if (__predict_false(xbd_map_align(xbdreq) != 0)) {
+ if (__predict_false(xbd_map_align(sc, xbdreq) != 0)) {
DPRINTF(("xbd_diskstart: no align\n"));
error = EAGAIN;
goto out;
@@ -1028,7 +1052,7 @@ xbd_diskstart(device_t self, struct buf
if (__predict_false(bus_dmamap_load(sc->sc_xbusd->xbusd_dmat,
xbdreq->req_dmamap, xbdreq->req_data, bp->b_bcount, NULL,
BUS_DMA_NOWAIT) != 0)) {
- printf("%s: %s: xengnt_grant_access failed",
+ printf("%s: %s: bus_dmamap_load failed",
device_xname(sc->sc_dksc.sc_dev), __func__);
error = EINVAL;
goto out;
@@ -1071,6 +1095,8 @@ xbd_diskstart(device_t self, struct buf
}
bus_dmamap_unload(sc->sc_xbusd->xbusd_dmat,
xbdreq->req_dmamap);
+ if (__predict_false(bp->b_data != xbdreq->req_data))
+ xbd_unmap_align(sc, xbdreq, false);
SLIST_INSERT_HEAD(&sc->sc_xbdreq_head, xbdreq,
req_next);
error = EFAULT;
@@ -1092,15 +1118,16 @@ out:
}
static int
-xbd_map_align(struct xbd_req *req)
+xbd_map_align(struct xbd_xenbus_softc *sc, struct xbd_req *req)
{
- int rc;
+ if (!sc->sc_unalign_free) {
+ sc->sc_cnt_unalign_busy.ev_count++;
+ return EAGAIN;
+ }
+ sc->sc_unalign_free = false;
- rc = uvm_km_kmem_alloc(kmem_va_arena,
- req->req_bp->b_bcount, (VM_NOSLEEP | VM_INSTANTFIT),
- (vmem_addr_t *)&req->req_data);
- if (__predict_false(rc != 0))
- return ENOMEM;
+ KASSERT(req->req_bp->b_bcount < MAXPHYS);
+ req->req_data = (void *)sc->sc_unalign_buffer;
if ((req->req_bp->b_flags & B_READ) == 0)
memcpy(req->req_data, req->req_bp->b_data,
req->req_bp->b_bcount);
@@ -1108,10 +1135,10 @@ xbd_map_align(struct xbd_req *req)
}
static void
-xbd_unmap_align(struct xbd_req *req)
+xbd_unmap_align(struct xbd_xenbus_softc *sc, struct xbd_req *req, bool sync)
{
- if (req->req_bp->b_flags & B_READ)
+ if (sync && req->req_bp->b_flags & B_READ)
memcpy(req->req_bp->b_data, req->req_data,
req->req_bp->b_bcount);
- uvm_km_kmem_free(kmem_va_arena, (vaddr_t)req->req_data, req->req_bp->b_bcount);
+ sc->sc_unalign_free = true;
}
