linux-kernel - RE: [PATCH v2] Drivers: vmbus: Check for channel allocation before looking up relids

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Date:   Fri, 17 Feb 2023 10:51:39 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Dexuan Cui <decui@...rosoft.com>,
        Mohammed Gamal <mgamal@...hat.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        "parri.andrea@...il.com" <parri.andrea@...il.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        "xxiong@...hat.com" <xxiong@...hat.com>
Subject: RE: [PATCH v2] Drivers: vmbus: Check for channel allocation before
 looking up relids

Dexuan Cui <decui@...rosoft.com> writes:

>> From: Mohammed Gamal <mgamal@...hat.com>
>> Sent: Tuesday, February 14, 2023 3:28 AM
>> ...
>> So Make relid2channel() check if vmbus channels is allocated first, and if not
>> print a warning and return NULL to the caller.
> Can we change the above to:
>
> Print a warning and error out in relid2channel() for a channel id that's invalid
> in the second kernel.
>  
>> --- a/drivers/hv/connection.c
>> +++ b/drivers/hv/connection.c
>> @@ -409,6 +409,10 @@ void vmbus_disconnect(void)
>>   */
>>  struct vmbus_channel *relid2channel(u32 relid)
>>  {
>> +	if (vmbus_connection.channels == NULL) {
>> +		WARN(1, "Requested relid=%u, but channel mapping not
>> allocated!\n", relid);
>
> WARN() may be too noisy. I suggest we use pr_warn() instead.
>
> Can we make the line a little shorter:
>         pr_warn("relid2channel: invalid channel id %u\n", relid);
>

I'd even suggest to make it pr_warn_once() to be
safe. In theory, vmbus_chan_sched() call site looks like it can create a
lot of noise.

-- 
Vitaly