diff options
| author | Kimberly Brown <kimbrownkd@gmail.com> | 2019-03-14 16:05:15 -0400 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2019-04-10 18:58:56 -0400 |
| commit | 14948e39445db674516ccabdf01090586ecfdc9b (patch) | |
| tree | c7dde66befabf1f3d78652672c73ff0f1ec5ea62 /drivers/hv/ring_buffer.c | |
| parent | 4713eb7b580a269f827ea82f4c25bebae963e0e8 (diff) | |
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 <kimbrownkd@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/hv/ring_buffer.c')
| -rw-r--r-- | drivers/hv/ring_buffer.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 0386ff48c5ea..121a01c43298 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -166,14 +166,18 @@ hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi, } /* Get various debug metrics for the specified ring buffer. */ -int hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info, +int hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, struct hv_ring_buffer_debug_info *debug_info) { u32 bytes_avail_towrite; u32 bytes_avail_toread; - if (!ring_info->ring_buffer) + mutex_lock(&ring_info->ring_buffer_mutex); + + if (!ring_info->ring_buffer) { + mutex_unlock(&ring_info->ring_buffer_mutex); return -EINVAL; + } hv_get_ringbuffer_availbytes(ring_info, &bytes_avail_toread, @@ -184,10 +188,19 @@ int hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info, debug_info->current_write_index = ring_info->ring_buffer->write_index; debug_info->current_interrupt_mask = ring_info->ring_buffer->interrupt_mask; + mutex_unlock(&ring_info->ring_buffer_mutex); + return 0; } EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo); +/* Initialize a channel's ring buffer info mutex locks */ +void hv_ringbuffer_pre_init(struct vmbus_channel *channel) +{ + mutex_init(&channel->inbound.ring_buffer_mutex); + mutex_init(&channel->outbound.ring_buffer_mutex); +} + /* Initialize the ring buffer. */ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, struct page *pages, u32 page_cnt) @@ -240,8 +253,10 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, /* Cleanup the ring buffer. */ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) { + mutex_lock(&ring_info->ring_buffer_mutex); vunmap(ring_info->ring_buffer); ring_info->ring_buffer = NULL; + mutex_unlock(&ring_info->ring_buffer_mutex); } /* Write to the ring buffer. */ |