From 433e19cf33d34bb6751c874a9c00980552fe508c Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Sat, 28 Jan 2017 11:46:02 -0700 Subject: Drivers: hv: vmbus: finally fix hv_need_to_signal_on_read() Commit a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in hv_need_to_signal_on_read()") added the proper mb(), but removed the test "prev_write_sz < pending_sz" when making the signal decision. As a result, the guest can signal the host unnecessarily, and then the host can throttle the guest because the host thinks the guest is buggy or malicious; finally the user running stress test can perceive intermittent freeze of the guest. This patch brings back the test, and properly handles the in-place consumption APIs used by NetVSC (see get_next_pkt_raw(), put_pkt_raw() and commit_rd_index()). Fixes: a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in hv_need_to_signal_on_read()") Signed-off-by: Dexuan Cui Reported-by: Rolf Neugebauer Tested-by: Rolf Neugebauer Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Cc: Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/ring_buffer.c | 1 + drivers/net/hyperv/netvsc.c | 6 ++++++ 2 files changed, 7 insertions(+) (limited to 'drivers') diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index cd49cb17eb7f..308dbda700eb 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -383,6 +383,7 @@ int hv_ringbuffer_read(struct vmbus_channel *channel, return ret; } + init_cached_read_index(channel); next_read_location = hv_get_next_read_location(inring_info); next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc, sizeof(desc), diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index 5a1cc089acb7..86e5749226ef 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -1295,6 +1295,9 @@ void netvsc_channel_cb(void *context) ndev = hv_get_drvdata(device); buffer = get_per_channel_state(channel); + /* commit_rd_index() -> hv_signal_on_read() needs this. */ + init_cached_read_index(channel); + do { desc = get_next_pkt_raw(channel); if (desc != NULL) { @@ -1347,6 +1350,9 @@ void netvsc_channel_cb(void *context) bufferlen = bytes_recvd; } + + init_cached_read_index(channel); + } while (1); if (bufferlen > NETVSC_PACKET_SIZE) -- cgit v1.2.3