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authorVitaly Kuznetsov <vkuznets@redhat.com>2016-09-02 15:58:20 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-09-02 18:22:51 +0300
commit9988ce685676cebe0b14dc128f00e1ae9cd1a4fa (patch)
tree5f7e2212bca74c839e686068b74ca3b3dec5d739 /drivers/hv/ring_buffer.c
parent98f531b10d23e3c28e8d34c0e88822a81231b3c2 (diff)
downloadlinux-9988ce685676cebe0b14dc128f00e1ae9cd1a4fa.tar.xz
Drivers: hv: ring_buffer: wrap around mappings for ring buffers
Make it possible to always use a single memcpy() or to provide a direct link to a packet on the ring buffer by creating virtual mapping for two copies of the ring buffer with vmap(). Utilize currently empty hv_ringbuffer_cleanup() to do the unmap. While on it, replace sizeof(struct hv_ring_buffer) check in hv_ringbuffer_init() with BUILD_BUG_ON() as it is a compile time check. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Tested-by: Dexuan Cui <decui@microsoft.com> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv/ring_buffer.c')
-rw-r--r--drivers/hv/ring_buffer.c39
1 files changed, 33 insertions, 6 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index e3edcaee7ab3..7e21c2c82ad1 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -27,6 +27,8 @@
#include <linux/mm.h>
#include <linux/hyperv.h>
#include <linux/uio.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
#include "hyperv_vmbus.h"
@@ -243,22 +245,46 @@ void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
/* Initialize the ring buffer. */
int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
- void *buffer, u32 buflen)
+ struct page *pages, u32 page_cnt)
{
- if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
- return -EINVAL;
+ int i;
+ struct page **pages_wraparound;
+
+ BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));
memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
- ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
+ /*
+ * First page holds struct hv_ring_buffer, do wraparound mapping for
+ * the rest.
+ */
+ pages_wraparound = kzalloc(sizeof(struct page *) * (page_cnt * 2 - 1),
+ GFP_KERNEL);
+ if (!pages_wraparound)
+ return -ENOMEM;
+
+ pages_wraparound[0] = pages;
+ for (i = 0; i < 2 * (page_cnt - 1); i++)
+ pages_wraparound[i + 1] = &pages[i % (page_cnt - 1) + 1];
+
+ ring_info->ring_buffer = (struct hv_ring_buffer *)
+ vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP, PAGE_KERNEL);
+
+ kfree(pages_wraparound);
+
+
+ if (!ring_info->ring_buffer)
+ return -ENOMEM;
+
ring_info->ring_buffer->read_index =
ring_info->ring_buffer->write_index = 0;
/* Set the feature bit for enabling flow control. */
ring_info->ring_buffer->feature_bits.value = 1;
- ring_info->ring_size = buflen;
- ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
+ ring_info->ring_size = page_cnt << PAGE_SHIFT;
+ ring_info->ring_datasize = ring_info->ring_size -
+ sizeof(struct hv_ring_buffer);
spin_lock_init(&ring_info->ring_lock);
@@ -268,6 +294,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
/* Cleanup the ring buffer. */
void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
{
+ vunmap(ring_info->ring_buffer);
}
/* Write to the ring buffer. */