linux/drivers/hv/ring_buffer.c, branch v4.5

Drivers: hv: ring_buffer: eliminate hv_ringbuffer_peek()

2015-12-15T03:27:30Z

Currently, there is only one user for hv_ringbuffer_read()/ hv_ringbuffer_peak() functions and the usage of these functions is: - insecure as we drop ring_lock between them, someone else (in theory only) can acquire it in between; - non-optimal as we do a number of things (acquire/release the above mentioned lock, calculate available space on the ring, ...) twice and this path is performance-critical. Remove hv_ringbuffer_peek() moving the logic from __vmbus_recvpacket() to hv_ringbuffer_read(). Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: ring_buffer: remove code duplication from hv_ringbuffer_peek/read()

2015-12-15T03:27:30Z

hv_ringbuffer_peek() does the same as hv_ringbuffer_read() without advancing the read index. The only functional change this patch brings is moving hv_need_to_signal_on_read() call under the ring_lock but this function is just a couple of comparisons. Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: ring_buffer.c: fix comment style

2015-12-15T03:27:30Z

Convert 6+-string comments repeating function names to normal kernel-style comments and fix a couple of other comment style issues. No textual or functional changes intended. Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv_vmbus: Fix signal to host condition

2015-08-05T18:44:29Z

Fixes a bug where previously hv_ringbuffer_read would pass in the old number of bytes available to read instead of the expected old read index when calculating when to signal to the host that the ringbuffer is empty. Since the previous write size is already saved, also changes the hv_need_to_signal_on_read to use the previously read value rather than recalculating it. Signed-off-by: Christopher Oo Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Enable interrupt driven flow control

2014-09-24T06:31:22Z

In win8 we have a feature that allows for interrupt driven flow management for host/guest communication. For instance, if the host were blocked because there was no space available in the ringbuffer, the host could request that the guest send an interrupt when space becomes available in the ringbuffer (when the guest drains the ringbuffer). While this feature was implemented in the guest a while ago, we had not advertised that the guest supported this feature. This patch advertises the support to the host. For pre-win8 hosts, this has no effect since the size of the ringbuffer control structure has not changed and all changes have been backward compatible - unused/reserved space has been used to implement this feature. In this version of the patch I have cleaned up the commit log based on feedback from Greg KH. Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Cleanup the packet send path

2014-02-07T23:22:40Z

The current channel code is using scatterlist abstraction to pass data to the ringbuffer API on the send path. This causes unnecessary translations between virtual and physical addresses. Fix this. Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

drivers: hv: check interrupt mask before read_index

2013-06-24T23:24:17Z

This patches add a read barriers to force the driver to check the interrupt mask before read_index. Otherwise we may lost a kick to host. Cc: K. Y. Srinivasan Cc: Haiyang Zhang Signed-off-by: Jason Wang Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

drivers: hv: switch to use mb() instead of smp_mb()

2013-06-18T18:14:18Z

Even if guest were compiled without SMP support, it could not assume that host wasn't. So switch to use mb() instead of smp_mb() to force memory barriers for UP guest. Signed-off-by: Jason Wang Cc: Haiyang Zhang Cc: stable Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Fix a bug in hv_need_to_signal()

2013-04-01T19:29:52Z

As part of updating the vmbus protocol, the function hv_need_to_signal() was introduced. This functions helps optimize signalling from guest to host. The newly added memory barrier is needed to ensure that we correctly decide when to signal the host. Signed-off-by: K. Y. Srinivasan Reviewed-by: Haiyang Zhang Reported-by: Olaf Hering Cc: Stable (V3.8+) Signed-off-by: Greg Kroah-Hartman

Drivers: hv: Implement flow management on the send side

2013-01-17T19:41:49Z

Implement flow management on the send side. When the sender is blocked, the reader can potentially signal the sender to indicate there is now room to send. Signed-off-by: K. Y. Srinivasan Reviewed-by: Haiyang Zhang Signed-off-by: Greg Kroah-Hartman