[Xen-devel] [PATCH v4 1/2] xen/blkback: add stack variable 'blkif' in connect_ring()

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

As 'be->blkif' is used for many times in connect_ring(), the stack variable
'blkif' is added to substitute 'be-blkif'.

Suggested-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
 drivers/block/xen-blkback/xenbus.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c 
b/drivers/block/xen-blkback/xenbus.c
index a4bc74e..a4aadac 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -1023,6 +1023,7 @@ static int read_per_ring_refs(struct xen_blkif_ring 
*ring, const char *dir)
 static int connect_ring(struct backend_info *be)
 {
        struct xenbus_device *dev = be->dev;
+       struct xen_blkif *blkif = be->blkif;
        unsigned int pers_grants;
        char protocol[64] = "";
        int err, i;
@@ -1033,25 +1034,25 @@ static int connect_ring(struct backend_info *be)
 
        pr_debug("%s %s\n", __func__, dev->otherend);
 
-       be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
+       blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
        err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol",
                           "%63s", protocol);
        if (err <= 0)
                strcpy(protocol, "unspecified, assuming default");
        else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
-               be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
+               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;
+               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;
+               blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
        else {
                xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
                return -ENOSYS;
        }
        pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent",
                                           0);
-       be->blkif->vbd.feature_gnt_persistent = pers_grants;
-       be->blkif->vbd.overflow_max_grants = 0;
+       blkif->vbd.feature_gnt_persistent = pers_grants;
+       blkif->vbd.overflow_max_grants = 0;
 
        /*
         * Read the number of hardware queues from frontend.
@@ -1067,16 +1068,16 @@ static int connect_ring(struct backend_info *be)
                                requested_num_queues, xenblk_max_queues);
                return -ENOSYS;
        }
-       be->blkif->nr_rings = requested_num_queues;
-       if (xen_blkif_alloc_rings(be->blkif))
+       blkif->nr_rings = requested_num_queues;
+       if (xen_blkif_alloc_rings(blkif))
                return -ENOMEM;
 
        pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
-                be->blkif->nr_rings, be->blkif->blk_protocol, protocol,
+                blkif->nr_rings, blkif->blk_protocol, protocol,
                 pers_grants ? "persistent grants" : "");
 
-       if (be->blkif->nr_rings == 1)
-               return read_per_ring_refs(&be->blkif->rings[0], dev->otherend);
+       if (blkif->nr_rings == 1)
+               return read_per_ring_refs(&blkif->rings[0], dev->otherend);
        else {
                xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
                xspath = kmalloc(xspathsize, GFP_KERNEL);
@@ -1085,10 +1086,10 @@ static int connect_ring(struct backend_info *be)
                        return -ENOMEM;
                }
 
-               for (i = 0; i < be->blkif->nr_rings; i++) {
+               for (i = 0; i < blkif->nr_rings; i++) {
                        memset(xspath, 0, xspathsize);
                        snprintf(xspath, xspathsize, "%s/queue-%u", 
dev->otherend, i);
-                       err = read_per_ring_refs(&be->blkif->rings[i], xspath);
+                       err = read_per_ring_refs(&blkif->rings[i], xspath);
                        if (err) {
                                kfree(xspath);
                                return err;
-- 
2.7.4


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