• Kimberly Brown's avatar
    Drivers: hv: vmbus: Fix race condition with new ring_buffer_info mutex · 14948e39
    Kimberly Brown authored
    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: default avatarKimberly Brown <kimbrownkd@gmail.com>
    Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
    14948e39
hyperv_vmbus.h 9.69 KB