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SubjectRE: [PATCH v4 1/2] xen/blkback: add stack variable 'blkif' in connect_ring()
Date
> -----Original Message-----
> From: Dongli Zhang [mailto:dongli.zhang@oracle.com]
> Sent: 07 January 2019 05:36
> To: xen-devel@lists.xenproject.org; linux-block@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Cc: konrad.wilk@oracle.com; Roger Pau Monne <roger.pau@citrix.com>;
> axboe@kernel.dk; Paul Durrant <Paul.Durrant@citrix.com>
> Subject: [PATCH v4 1/2] xen/blkback: add stack variable 'blkif' in
> connect_ring()
>
> 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@citrix.com>
> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>

That looks better :-)

Reviewed-by: Paul Durrant <paul.durrant@citrix.com>

> ---
> 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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