From 14948e39445db674516ccabdf01090586ecfdc9b Mon Sep 17 00:00:00 2001 From: Kimberly Brown Date: Thu, 14 Mar 2019 16:05:15 -0400 Subject: Drivers: hv: vmbus: Fix race condition with new ring_buffer_info mutex Fix a race condition that can result in a ring buffer pointer being set to null while a "_show" function is reading the ring buffer's data. This problem was discussed here: https://lkml.org/lkml/2018/10/18/779 To fix the race condition, add a new mutex lock to the "hv_ring_buffer_info" struct. Add a new function, "hv_ringbuffer_pre_init()", where a channel's inbound and outbound ring_buffer_info mutex locks are initialized. Acquire/release the locks in the "hv_ringbuffer_cleanup()" function, which is where the ring buffer pointers are set to null. Acquire/release the locks in the four channel-level "_show" functions that access ring buffer data. Remove the "const" qualifier from the "vmbus_channel" parameter and the "rbi" variable of the channel-level "_show" functions so that the locks can be acquired/released in these functions. Acquire/release the locks in hv_ringbuffer_get_debuginfo(). Remove the "const" qualifier from the "hv_ring_buffer_info" parameter so that the locks can be acquired/released in this function. Signed-off-by: Kimberly Brown Reviewed-by: Michael Kelley Signed-off-by: Sasha Levin --- drivers/hv/channel_mgmt.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/hv/channel_mgmt.c') diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index d32cac501fc7..3fc0b247a807 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -336,6 +336,8 @@ static struct vmbus_channel *alloc_channel(void) tasklet_init(&channel->callback_event, vmbus_on_event, (unsigned long)channel); + hv_ringbuffer_pre_init(channel); + return channel; } -- cgit v1.2.3