Re: [PATCH] Drivers: hv: vmbus: Return -EINVAL for the sys files for unopened channels

Stephen Hemminger
2018-12-17T17:15:47Z

On Thu, 13 Dec 2018 16:35:43 +0000
Dexuan Cui <decui@microsoft.com> wrote:

> Before 98f4c651762c, we returned zeros for unopened channels.
> With 98f4c651762c, we started to return random on-stack values.
>
> We'd better return -EINVAL instead.
>
> Fixes: 98f4c651762c ("hv: move ringbuffer bus attributes to dev_groups")
> Cc: stable@vger.kernel.org
> Cc: K. Y. Srinivasan <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>

The concept looks fine, but maybe it would be simpler to move it into
hv_ringbuffer_get_debuginfo and have it return an error code.

Since so much of the code is repeated, I would probably make a
macro which generates the code as well.

Something like this:

From c6bbdbcde933c85098f7b3e71650a8479d52810c Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <sthemmin@microsoft.com>
Date: Mon, 17 Dec 2018 09:13:24 -0800
Subject: [PATCH] hv: vmbus: check for ring in debug info

---
drivers/hv/ring_buffer.c | 31 +++++++++---------
drivers/hv/vmbus_drv.c | 71 ++++++++++++++++++++++++++++++++++------
include/linux/hyperv.h | 5 +--
3 files changed, 79 insertions(+), 28 deletions(-)

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 64d0c85d5161..1f1a55e07733 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -164,26 +164,25 @@ hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
}

/* Get various debug metrics for the specified ring buffer. */
-void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
- struct hv_ring_buffer_debug_info *debug_info)
+int hv_ringbuffer_get_debuginfo(const 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) {
- hv_get_ringbuffer_availbytes(ring_info,
- &bytes_avail_toread,
- &bytes_avail_towrite);
-
- debug_info->bytes_avail_toread = bytes_avail_toread;
- debug_info->bytes_avail_towrite = bytes_avail_towrite;
- debug_info->current_read_index =
- ring_info->ring_buffer->read_index;
- debug_info->current_write_index =
- ring_info->ring_buffer->write_index;
- debug_info->current_interrupt_mask =
- ring_info->ring_buffer->interrupt_mask;
- }
+ if (!ring_info->ring_buffer)
+ return -EINVAL;
+
+ hv_get_ringbuffer_availbytes(ring_info,
+ &bytes_avail_toread,
+ &bytes_avail_towrite);
+ debug_info->bytes_avail_toread = bytes_avail_toread;
+ debug_info->bytes_avail_towrite = bytes_avail_towrite;
+ debug_info->current_read_index = ring_info->ring_buffer->read_index;
+ debug_info->current_write_index = ring_info->ring_buffer->write_index;
+ debug_info->current_interrupt_mask
+ = ring_info->ring_buffer->interrupt_mask;
+ return 0;
}
EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo);

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 283d184280af..403fee01572c 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -313,10 +313,16 @@ static ssize_t out_intr_mask_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info outbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+ &outbound);
+ if (ret < 0)
+ return ret;
+
return sprintf(buf, "%d\n", outbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(out_intr_mask);
@@ -326,10 +332,15 @@ static ssize_t out_read_index_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info outbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+ &outbound);
+ if (ret < 0)
+ return ret;
return sprintf(buf, "%d\n", outbound.current_read_index);
}
static DEVICE_ATTR_RO(out_read_index);
@@ -340,10 +351,15 @@ static ssize_t out_write_index_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info outbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+ &outbound);
+ if (ret < 0)
+ return ret;
return sprintf(buf, "%d\n", outbound.current_write_index);
}
static DEVICE_ATTR_RO(out_write_index);
@@ -354,10 +370,15 @@ static ssize_t out_read_bytes_avail_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info outbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+ &outbound);
+ if (ret < 0)
+ return ret;
return sprintf(buf, "%d\n", outbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(out_read_bytes_avail);
@@ -368,10 +389,15 @@ static ssize_t out_write_bytes_avail_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info outbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
+ &outbound);
+ if (ret < 0)
+ return ret;
return sprintf(buf, "%d\n", outbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(out_write_bytes_avail);
@@ -381,10 +407,15 @@ static ssize_t in_intr_mask_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info inbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+ if (ret < 0)
+ return ret;
+
return sprintf(buf, "%d\n", inbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(in_intr_mask);
@@ -394,10 +425,15 @@ static ssize_t in_read_index_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info inbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+ if (ret < 0)
+ return ret;
+
return sprintf(buf, "%d\n", inbound.current_read_index);
}
static DEVICE_ATTR_RO(in_read_index);
@@ -407,10 +443,15 @@ static ssize_t in_write_index_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info inbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+ if (ret < 0)
+ return ret;
+
return sprintf(buf, "%d\n", inbound.current_write_index);
}
static DEVICE_ATTR_RO(in_write_index);
@@ -421,10 +462,15 @@ static ssize_t in_read_bytes_avail_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info inbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+ if (ret < 0)
+ return ret;
+
return sprintf(buf, "%d\n", inbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(in_read_bytes_avail);
@@ -435,10 +481,15 @@ static ssize_t in_write_bytes_avail_show(struct device *dev,
{
struct hv_device *hv_dev = device_to_hv_device(dev);
struct hv_ring_buffer_debug_info inbound;
+ int ret;

if (!hv_dev->channel)
return -ENODEV;
- hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+
+ ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+ if (ret < 0)
+ return ret;
+
return sprintf(buf, "%d\n", inbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(in_write_bytes_avail);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 14131b6fae68..ed74888087f1 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1176,8 +1176,9 @@ struct hv_ring_buffer_debug_info {
u32 bytes_avail_towrite;
};

-void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
- struct hv_ring_buffer_debug_info *debug_info);
+
+int hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
+ struct hv_ring_buffer_debug_info *debug_info);

/* Vmbus interface */
#define vmbus_driver_register(driver) \
--
2.19.2