git: 89e3d5671ba1 - main - bsnmpclient(3): make it thread-safe

[Jessica Clarke]

On 29 Dec 2020, at 17:38, Konstantin Belousov <kostikbel at gmail.com> wrote:
> On Tue, Dec 29, 2020 at 03:11:55PM +0000, Jessica Clarke wrote:
>> On 29 Dec 2020, at 15:00, Edward Tomasz Napierala <trasz at FreeBSD.org> wrote:
>>> diff --git a/contrib/bsnmp/lib/snmpclient.c b/contrib/bsnmp/lib/snmpclient.c
>>> index c22d8e125a14..e49105918416 100644
>>> --- a/contrib/bsnmp/lib/snmpclient.c
>>> +++ b/contrib/bsnmp/lib/snmpclient.c
>>> @@ -71,7 +71,7 @@
>>> #define	DEBUG_PARSE	0
>>> 
>>> /* global context */
>>> -struct snmp_client snmp_client;
>>> +__thread struct snmp_client snmp_client;
>> 
>> That comment is no longer true.
>> 
>>> /* List of all outstanding requests */
>>> struct sent_pdu {
>>> @@ -86,7 +86,7 @@ struct sent_pdu {
>>> };
>>> LIST_HEAD(sent_pdu_list, sent_pdu);
>>> 
>>> -static struct sent_pdu_list sent_pdus;
>>> +__thread static struct sent_pdu_list sent_pdus;
>>> 
>>> /*
>>> * Prototype table entry. All C-structure produced by the table function must
>>> diff --git a/contrib/bsnmp/lib/snmpclient.h b/contrib/bsnmp/lib/snmpclient.h
>>> index a19bdb2ea653..1bc3780de038 100644
>>> --- a/contrib/bsnmp/lib/snmpclient.h
>>> +++ b/contrib/bsnmp/lib/snmpclient.h
>>> @@ -114,7 +114,7 @@ struct snmp_client {
>>> };
>>> 
>>> /* the global context */
>>> -extern struct snmp_client snmp_client;
>>> +extern __thread struct snmp_client snmp_client;
>> 
>> Ditto.
>> 
>> Is there really a documented requirement for everything to be called
>> from the same thread? I can see consumers of the library that already
>> use proper locking breaking because of this.
> 
> So this variable is supposed to be used by consumers ?
> The change requires the library version bump, at least.
> I suppose libsnmpclient does not use symbol versioning ?

The exported functions implicitly use them to track state.

Jess