Re: [pve-devel] [PATCH qemu-server 2/3] qmeventd: cancel 'forced cleanup' when normal cleanup succeeds

[Dominik Csapak <d.csapak@proxmox.com>]

On 9/22/22 12:14, Matthias Heiserer wrote:
> On 21.09.2022 14:49, Dominik Csapak wrote:
>> instead of always sending a SIGKILL to the target pid.
>> It was not that much of a problem since the timeout previously was 5
>> seconds and we used pifds where possible, thus the chance of killing the
>> wrong process was rather slim.
>>
>> Now we increased the timeout to 60s which makes the race a bit more likely
>> (when not using pidfds), so remove it from the 'forced_cleanups' list when
>> the normal cleanup succeeds.
>>
>> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
>> ---
>>   qmeventd/qmeventd.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/qmeventd/qmeventd.c b/qmeventd/qmeventd.c
>> index e9ff5b3..de5efd0 100644
>> --- a/qmeventd/qmeventd.c
>> +++ b/qmeventd/qmeventd.c
>> @@ -415,6 +415,25 @@ cleanup_qemu_client(struct Client *client)
>>       }
>>   }
>> +static void
>> +remove_cleanup_data(void *ptr, void *client_ptr) {
> Not that it really matters, but is there a reason we don't use
> remove_cleanup_data(struct CleanupData *ptr, struct Client *client_ptr)
> and let the caller deal with types?
>> +    struct CleanupData *data = (struct CleanupData *)ptr;
>> +    struct Client *client = (struct Client *)client_ptr;
>> +
>> +    if (data->pid == client->pid) {
>> +    forced_cleanups = g_slist_remove(forced_cleanups, ptr);
>> +    free(ptr);
>> +    }
>> +}
>> + > +static void
>> +remove_from_forced_cleanup(struct Client *client) {
>> +    if (g_slist_length(forced_cleanups) > 0) {
>> +    VERBOSE_PRINT("removing %s from forced cleanups\n", client->qemu.vmid);
>> +    g_slist_foreach(forced_cleanups, remove_cleanup_data, client);
> that is, here `(void (*)(void*, void*)) remove_cleanup_data`. Seems a bit cleaner to me.
>> +    }
>> +}
>> +
>>   void
>>   cleanup_client(struct Client *client)
>>   {
>> @@ -441,6 +460,7 @@ cleanup_client(struct Client *client)
>>           break;
>>       }
>> +    remove_from_forced_cleanup(client);
>>       free(client);
>>   }
> 

i just kept the style we use for the existing call to *_foreach.

my guess is that the intention was to keep the function close to what glib defines
(although that uses 'gpointer'). doing as you suggested introduces a big
cast that is confusing to read IMHO (for people not that familiar with c at least ;) )
that could be solved with casting to 'GFunc' (not sure if that's considered good style?)
but in the end, i don't have strong feeling either way