Jan Beulich
2012-Mar-23 15:56 UTC
[PATCH] linux-2.6.18/block backends: simplify protocol negotiation and initialization
In the negotiation code we can use the simpler (and type safe)
xenbus_read() instead of xenbus_gather() for reading the "protocol"
node.
The initialization code can be considerably shrunk by using a macro to
abstract out the code common for all variants.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/drivers/xen/blkback/interface.c
+++ b/drivers/xen/blkback/interface.c
@@ -70,29 +70,22 @@ int blkif_map(blkif_t *blkif, grant_ref_
blkif->blk_ring_area = area;
switch (blkif->blk_protocol) {
+#define BLKBK_RING_INIT(p) ({ \
+ struct blkif_##p##_sring *sring = area->addr; \
+ BACK_RING_INIT(&blkif->blk_rings.p, sring, PAGE_SIZE); \
+ })
case BLKIF_PROTOCOL_NATIVE:
- {
- blkif_sring_t *sring;
- sring = (blkif_sring_t *)area->addr;
- BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
+ BLKBK_RING_INIT(native);
break;
- }
case BLKIF_PROTOCOL_X86_32:
- {
- blkif_x86_32_sring_t *sring_x86_32;
- sring_x86_32 = (blkif_x86_32_sring_t *)area->addr;
- BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
+ BLKBK_RING_INIT(x86_32);
break;
- }
case BLKIF_PROTOCOL_X86_64:
- {
- blkif_x86_64_sring_t *sring_x86_64;
- sring_x86_64 = (blkif_x86_64_sring_t *)area->addr;
- BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
+ BLKBK_RING_INIT(x86_64);
break;
- }
default:
BUG();
+#undef BLKBK_RING_INIT
}
err = bind_interdomain_evtchn_to_irqhandler(
--- a/drivers/xen/blkback/xenbus.c
+++ b/drivers/xen/blkback/xenbus.c
@@ -494,17 +494,14 @@ static int connect_ring(struct backend_i
}
be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
- err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
- NULL, &protocol, NULL);
- if (err)
+ protocol = xenbus_read(XBT_NIL, dev->otherend, "protocol", NULL);
+ if (IS_ERR(protocol))
protocol = NULL;
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
- else {
+ else if (0 != strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) {
xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
kfree(protocol);
return -1;
--- a/drivers/xen/blktap/interface.c
+++ b/drivers/xen/blktap/interface.c
@@ -71,29 +71,22 @@ int tap_blkif_map(blkif_t *blkif, struct
blkif->blk_ring_area = area;
switch (blkif->blk_protocol) {
+#define BLKTAP_RING_INIT(p) ({ \
+ struct blkif_##p##_sring *sring = area->addr; \
+ BACK_RING_INIT(&blkif->blk_rings.p, sring, PAGE_SIZE); \
+ })
case BLKIF_PROTOCOL_NATIVE:
- {
- blkif_sring_t *sring;
- sring = (blkif_sring_t *)area->addr;
- BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
+ BLKTAP_RING_INIT(native);
break;
- }
case BLKIF_PROTOCOL_X86_32:
- {
- blkif_x86_32_sring_t *sring_x86_32;
- sring_x86_32 = (blkif_x86_32_sring_t *)area->addr;
- BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
+ BLKTAP_RING_INIT(x86_32);
break;
- }
case BLKIF_PROTOCOL_X86_64:
- {
- blkif_x86_64_sring_t *sring_x86_64;
- sring_x86_64 = (blkif_x86_64_sring_t *)area->addr;
- BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
+ BLKTAP_RING_INIT(x86_64);
break;
- }
default:
BUG();
+#undef BLKTAP_RING_INIT
}
err = bind_interdomain_evtchn_to_irqhandler(
--- a/drivers/xen/blktap/xenbus.c
+++ b/drivers/xen/blktap/xenbus.c
@@ -447,17 +447,14 @@ static int connect_ring(struct backend_i
}
be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
- err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
- NULL, &protocol, NULL);
- if (err)
+ protocol = xenbus_read(XBT_NIL, dev->otherend, "protocol", NULL);
+ if (IS_ERR(protocol))
protocol = NULL;
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
- else {
+ else if (0 != strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) {
xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
kfree(protocol);
return -1;
--- a/include/xen/blkif.h
+++ b/include/xen/blkif.h
@@ -72,6 +72,7 @@ typedef struct blkif_x86_64_request blki
typedef struct blkif_x86_64_request blkif_x86_64_request_t;
typedef struct blkif_x86_64_response blkif_x86_64_response_t;
+#define blkif_native_sring blkif_sring
DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, struct
blkif_common_response);
DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, struct
blkif_x86_32_response);
DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, struct
blkif_x86_64_response);
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