[SSSD] [PATCH] Save all data to sysdb in one transaction

Stephen Gallagher sgallagh at redhat.com
Thu Jul 8 16:57:02 UTC 2010


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Just a reminder that it's been about a month since there was any
activity on this patch.


On 06/10/2010 07:53 AM, Stephen Gallagher wrote:
> On 06/10/2010 05:56 AM, Sumit Bose wrote:
>> Hi,
>>
>> this patch for master saves all IPA HBAC data in one transaction and
>> proceeds if the sysdb transaction fails. It addresses a review comment
>> from the "Use new schema for HBAC service checks" patch.
>>
>> The first patch changes the handling of the host data to be compatible
>> with the other data.
> 
> Nack.
> 
> I think it would be better form in set_local_and_remote_host_info() to 
> maintain a private memory context onto which to allocate the 
> hbac_host_info objects until we're ready to return, at which time they 
> should be stolen back onto mem_ctx.
> 
> This way if we end up in the failure condition, we don't exit the 
> function with potentially host_count chunks of memory of sizeof(struct 
> hbac_host_info) sitting around uselessly until the mem_ctx is eventually 
> freed.
> 
> For most functions, I wouldn't recommend this, but this particular 
> function has the potential of allocating a LOT of memory (if there are a 
> lot of HBAC rules on the server) and I'd prefer that we not hang onto it 
> if something goes wrong.
> 
>> The second removes the individual transactions and
>> introduces a common sysdb transaction.
>>
> 
> Nack.
> 
> In hbac_save_data_to_sysdb() you start a transaction, then create a 
> tmp_ctx, but if talloc_new() fails, you exit the function without 
> cancelling the transaction.
> 
> You have a memory leak on the success case of hbac_save_data_to_sysdb(). 
> You're not freeing tmp_ctx here. (Yeah, it's a short leak, as it will be 
> cleared when mem_ctx is, but it's bad form).
> 
> Similar to my comment about set_local_and_remote_host_info() in the 
> first patch, since it's possible for us to allocate a lot of memory (if 
> count is large) in hbac_save_list(), I think it makes sense to do 
> allocations in this function in a tmp_ctx. Furthermore, unless I'm 
> reading this wrong, the allocation made here does not get returned to 
> the calling function, so proper memory management policy would be to 
> clean it up here.
> 
> We probably shouldn't be passing in a mem_ctx to hbac_save_list() at 
> all. The function does not return anything up the stack, so we should 
> contain its memory usage entirely within the function.
> 
> As a note for the future, I don't see a purpose for passing mem_ctx to 
> sysdb_delete_recursive() either. It returns no values that we are 
> supposed to be responsible for, so having it attach to our memory 
> context is a bad idea. It should attach to a new toplevel context 
> instead, so valgrind would notice if we ever forget to free it properly.
> 
>> Do we want/need a similar patch for master, too?
> I'm assuming you mean sssd-1-2 here. I don't think we're likely to hit 
> situations where the sysdb can't be saved very often, so I'd suggest 
> leaving it out of sssd-1-2 unless we get bugs reported on it.
> 
> 


- -- 
Stephen Gallagher
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