lkml.org 
[lkml]   [2018]   [Oct]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH V2 3/4] vmbus: add per-channel sysfs info
Am Sun, 17 Sep 2017 20:54:18 -0700
schrieb kys@exchange.microsoft.com:

> This extends existing vmbus related sysfs structure to provide per-channel
> state information. This is useful when diagnosing issues with multiple
> queues in networking and storage.

> +++ b/drivers/hv/vmbus_drv.c
> +static ssize_t write_avail_show(const struct vmbus_channel *channel, char *buf)
> +{
> + const struct hv_ring_buffer_info *rbi = &channel->outbound;
> +
> + return sprintf(buf, "%u\n", hv_get_bytes_to_write(rbi));
> +}
> +VMBUS_CHAN_ATTR_RO(write_avail);

This is upstream since a year.

But I wonder how this can work if vmbus_device_register is called,
and then something reads the populated sysfs files before vmbus_open returns.
Nothing protects rbi->ring_buffer in this case, which remains NULL
until vmbus_open populates it.

A simple reproduce, with a modular kernel, is to boot with init=/bin/bash
head /sys/bus/vmbus/devices/*/channels/*/*

Olaf
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2018-10-18 17:27    [W:0.113 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site