Re: Possible uninitialized use of the variables (src/backend/access/transam/twophase.c)
Em dom., 13 de fev. de 2022 às 23:07, Michael Paquier escreveu: > On Thu, Feb 10, 2022 at 11:38:44AM +0900, Michael Paquier wrote: > > The proposed change is incomplete anyway once you consider this > > argument. First, there is no need to set up those fields in > > EndPrepare() anymore if there is no origin data, no? It would be good > > to comment that these are filled in EndPrepare(), I guess, once you do > > the initialization in StartPrepare(). > > That still looked better on a fresh look in terms of consistency, so > applied this way. > Thanks. regards, Ranier Vilela
Re: Possible uninitialized use of the variables (src/backend/access/transam/twophase.c)
At Mon, 14 Feb 2022 11:07:19 +0900, Michael Paquier wrote in > On Thu, Feb 10, 2022 at 11:38:44AM +0900, Michael Paquier wrote: > > The proposed change is incomplete anyway once you consider this > > argument. First, there is no need to set up those fields in > > EndPrepare() anymore if there is no origin data, no? It would be good > > to comment that these are filled in EndPrepare(), I guess, once you do > > the initialization in StartPrepare(). > > That still looked better on a fresh look in terms of consistency, so > applied this way. FWIW +1. That is what I had in my mind at the time of posting my comment, but I choosed not to make a change. It is one way to keep consistency. (And works to silence Coverity.) regards. -- Kyotaro Horiguchi NTT Open Source Software Center
Re: Possible uninitialized use of the variables (src/backend/access/transam/twophase.c)
On Thu, Feb 10, 2022 at 11:38:44AM +0900, Michael Paquier wrote: > The proposed change is incomplete anyway once you consider this > argument. First, there is no need to set up those fields in > EndPrepare() anymore if there is no origin data, no? It would be good > to comment that these are filled in EndPrepare(), I guess, once you do > the initialization in StartPrepare(). That still looked better on a fresh look in terms of consistency, so applied this way. -- Michael signature.asc Description: PGP signature
Re: Possible uninitialized use of the variables (src/backend/access/transam/twophase.c)
On Thu, Feb 10, 2022 at 10:18:15AM +0900, Kyotaro Horiguchi wrote: > Who repoerted that to you? Let's bet on Coverity. > StartPrepare and EndPrepare are virtually a single function that > accepts some additional operations in the middle. StartPrepare leaves > the "records" incomplete then EndPrepare completes it. It is not > designed so that the fields are accessed from others before the > completion. There seems to be no critical reasons for EndPrepare to > do the pointed operations, but looking that another replorigin-related > operation is needed in the same function, it is sensible that the > author intended to consolidate all replorigin related changes in > EndPrepare. Well, that's the intention I recall from reading this code a couple of weeks ago. In the worst case, this could be considered as a bad practice as having clean data helps at least debugging if you look at this data between the calls of StartPrepare() and EndPrepare(), and we do things this way for all the other fields, like total_len. The proposed change is incomplete anyway once you consider this argument. First, there is no need to set up those fields in EndPrepare() anymore if there is no origin data, no? It would be good to comment that these are filled in EndPrepare(), I guess, once you do the initialization in StartPrepare(). I agree that those changes are purely cosmetic. -- Michael diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c index 608c5149e5..874c8ed125 100644 --- a/src/backend/access/transam/twophase.c +++ b/src/backend/access/transam/twophase.c @@ -1074,6 +1074,9 @@ StartPrepare(GlobalTransaction gxact) hdr.ninvalmsgs = xactGetCommittedInvalidationMessages(, ); hdr.gidlen = strlen(gxact->gid) + 1; /* Include '\0' */ + /* EndPrepare will fill the origin data, if necessary */ + hdr.origin_lsn = InvalidXLogRecPtr; + hdr.origin_timestamp = 0; save_state_data(, sizeof(TwoPhaseFileHeader)); save_state_data(gxact->gid, hdr.gidlen); @@ -1133,11 +1136,6 @@ EndPrepare(GlobalTransaction gxact) hdr->origin_lsn = replorigin_session_origin_lsn; hdr->origin_timestamp = replorigin_session_origin_timestamp; } - else - { - hdr->origin_lsn = InvalidXLogRecPtr; - hdr->origin_timestamp = 0; - } /* * If the data size exceeds MaxAllocSize, we won't be able to read it in signature.asc Description: PGP signature
Re: Possible uninitialized use of the variables (src/backend/access/transam/twophase.c)
At Wed, 9 Feb 2022 08:15:45 -0300, Ranier Vilela wrote in > Hi, > > Commit > https://github.com/postgres/postgres/commit/1eb6d6527aae264b3e0b9c95aa70bb7a594ad1cf, > modified > data struct TwoPhaseFileHeader and added two new fields: > > XLogRecPtr origin_lsn; /* lsn of this record at origin node */ > TimestampTz origin_timestamp; /* time of prepare at origin node */ > > I think thay forgot initialize these fields in the function StartPrepare > because, > when calling function save_state_data(, sizeof(TwoPhaseFileHeader)); > > I have one report about possible uninitialized usage of the variables. Who repoerted that to you? StartPrepare and EndPrepare are virtually a single function that accepts some additional operations in the middle. StartPrepare leaves the "records" incomplete then EndPrepare completes it. It is not designed so that the fields are accessed from others before the completion. There seems to be no critical reasons for EndPrepare to do the pointed operations, but looking that another replorigin-related operation is needed in the same function, it is sensible that the author intended to consolidate all replorigin related changes in EndPrepare. So, my humble opinion here is, that change is not needed. regards. -- Kyotaro Horiguchi NTT Open Source Software Center