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Subject[PATCH 1/3] drivers: hv: vmbus: Introduce latency testing
Introduce user specified latency in the packet reception path.

Signed-off-by: Branden Bonaby <brandonbonaby94@gmail.com>
---
drivers/hv/connection.c | 5 +++++
drivers/hv/ring_buffer.c | 10 ++++++++++
include/linux/hyperv.h | 14 ++++++++++++++
3 files changed, 29 insertions(+)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 09829e15d4a0..2a2c22f5570e 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -354,9 +354,14 @@ void vmbus_on_event(unsigned long data)
{
struct vmbus_channel *channel = (void *) data;
unsigned long time_limit = jiffies + 2;
+ struct vmbus_channel *test_channel = !channel->primary_channel ?
+ channel :
+ channel->primary_channel;

trace_vmbus_on_event(channel);

+ if (unlikely(test_channel->fuzz_testing_buffer_delay > 0))
+ udelay(test_channel->fuzz_testing_buffer_delay);
do {
void (*callback_fn)(void *);

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 9a03b163cbbd..d7627c9023d6 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -395,7 +395,12 @@ struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
{
struct hv_ring_buffer_info *rbi = &channel->inbound;
struct vmpacket_descriptor *desc;
+ struct vmbus_channel *test_channel = !channel->primary_channel ?
+ channel :
+ channel->primary_channel;

+ if (unlikely(test_channel->fuzz_testing_message_delay > 0))
+ udelay(test_channel->fuzz_testing_message_delay);
if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
return NULL;

@@ -420,7 +425,12 @@ __hv_pkt_iter_next(struct vmbus_channel *channel,
struct hv_ring_buffer_info *rbi = &channel->inbound;
u32 packetlen = desc->len8 << 3;
u32 dsize = rbi->ring_datasize;
+ struct vmbus_channel *test_channel = !channel->primary_channel ?
+ channel :
+ channel->primary_channel;

+ if (unlikely(test_channel->fuzz_testing_message_delay > 0))
+ udelay(test_channel->fuzz_testing_message_delay);
/* bump offset to next potential packet */
rbi->priv_read_index += packetlen + VMBUS_PKT_TRAILER;
if (rbi->priv_read_index >= dsize)
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 6256cc34c4a6..8d068956dd67 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -23,6 +23,7 @@
#include <linux/mod_devicetable.h>
#include <linux/interrupt.h>
#include <linux/reciprocal_div.h>
+#include <linux/delay.h>

#define MAX_PAGE_BUFFER_COUNT 32
#define MAX_MULTIPAGE_BUFFER_COUNT 32 /* 128K */
@@ -926,6 +927,19 @@ struct vmbus_channel {
* full outbound ring buffer.
*/
u64 out_full_first;
+
+ /* enabling/disabling fuzz testing on the channel (default is false)*/
+ bool fuzz_testing_state;
+
+ /* Buffer delay will delay the guest from emptying the ring buffer
+ * for a specific amount of time. The delay is in microseconds and will
+ * be between 1 to a maximum of 1000, its default is 0 (no delay).
+ * The Message delay will delay guest reading on a per message basis
+ * in microseconds between 1 to 1000 with the default being 0
+ * (no delay).
+ */
+ u32 fuzz_testing_buffer_delay;
+ u32 fuzz_testing_message_delay;
};

static inline bool is_hvsock_channel(const struct vmbus_channel *c)
--
2.17.1
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