Bug#1023654: liburing 2.3 breaks binary compatibility
08.11.2022 17:50, Michael Tokarev wrote: 08.11.2022 17:11, Guillem Jover wrote: [..] If you are really seeing samba linked against old liburing not working with the new liburing, then we'd need to dig further to see what else might be missing, but I'm currently not seeing it just by a very quick code staring. Well. I already deleted my test chroot. I can't say for 100% now that it breaks the other way around. I'll have to double-check. It took me quite quite some time especially due to other urgent things I'm doing today. I can check if 2.2-compiled samba works with 2.3-uring but a bit later today. Even if it works, it is not exactly conclusive, since samba only uses certain code paths. But ofc if it doesn't work, it *is* conclusive :) Ok, I double-verified this: samba compiled against older liburing works with liburing 2.3 after upgrading liburing2 package. So it must be just me being too tired when debugging all this. So it appears to be backwards- compatible (non-conclusive! ;)), just needs new lib for newly compiled programs. It's a rare case really, because of the rather heavy usage of inline functions for access, - so parts of the library are actually compiled into the program, and now you've more pieces to keep in sync. It's an interesting case really. Thank you! /mjt
Bug#1023654: liburing 2.3 breaks binary compatibility
08.11.2022 16:44, Guillem Jover wrote: Hi! On Tue, 2022-11-08 at 16:32:25 +0300, Michael Tokarev wrote: On Tue, 08 Nov 2022 15:51:17 +0300 Michael Tokarev wrote: Source: liburing Version: 2.3-1 Severity: grave liburing 2.3 broke binary compatibility without bumping the soname. Indeed. :/ Should make a habit of checking the header diffs, as this is not the first time this has happened. Actually this is interesting. Maybe it would be better for me to just wait till new liburing migrates to testing, and re-run samba autopkgtests, instead of filing this bugreport... (Provided it works the other way around, which I'm not sure about yet). /mjt
Bug#1023654: liburing 2.3 breaks binary compatibility
08.11.2022 17:11, Guillem Jover wrote: [..] If you are really seeing samba linked against old liburing not working with the new liburing, then we'd need to dig further to see what else might be missing, but I'm currently not seeing it just by a very quick code staring. Well. I already deleted my test chroot. I can't say for 100% now that it breaks the other way around. I'll have to double-check. It took me quite quite some time especially due to other urgent things I'm doing today. I can check if 2.2-compiled samba works with 2.3-uring but a bit later today. Even if it works, it is not exactly conclusive, since samba only uses certain code paths. But ofc if it doesn't work, it *is* conclusive :) Thanks, /mjt
Bug#1023654: liburing 2.3 breaks binary compatibility
Hi! I've forwarded this upstream now. On Tue, 2022-11-08 at 14:44:25 +0100, Guillem Jover wrote: > On Tue, 2022-11-08 at 16:32:25 +0300, Michael Tokarev wrote: > > On Tue, 08 Nov 2022 15:51:17 +0300 Michael Tokarev wrote: > > > In liburing.h in 2.3, structures io_uring_cq and io_uring_sq changed > > > their sizes. Both of these structures are parts of io_uring structure > > > which the main part of the API. Here's the difference: > > > > > > @@ -43,7 +79,9 @@ > > > @@ -56,13 +94,18 @@ > > > size_t ring_sz; > > > void *ring_ptr; > > > - unsigned pad[4]; > > > + unsigned ring_mask; > > > + unsigned ring_entries; > > > + > > > + unsigned pad[2]; > > > > This does not look like it is changing the size actually, - I haven't > > noticed it adjusts pad[] accordingly. So this is not the issue here. > > > > But the end result is the same: samba compiled with liburing 2.2 does > > not work with runtime liburing 2.3, and samba compiled with liburing > > 2.3 does not work with runtime liburing 2.2. I've checked the code and this is weird, the new code is taking care of initializing all members with the new shared library. So I'd expect samba built against the old liburing to work with the new one. But the problem seems to be that code built against the new liburing will not work with the old liburing, as that one does not initialize the new members being used from the inline functions. If you are really seeing samba linked against old liburing not working with the new liburing, then we'd need to dig further to see what else might be missing, but I'm currently not seeing it just by a very quick code staring. Thanks, Guillem
Bug#1023654: liburing 2.3 breaks binary compatibility
Hi! On Tue, 2022-11-08 at 16:32:25 +0300, Michael Tokarev wrote: > On Tue, 08 Nov 2022 15:51:17 +0300 Michael Tokarev wrote: > > Source: liburing > > Version: 2.3-1 > > Severity: grave > > > > liburing 2.3 broke binary compatibility without bumping the soname. Indeed. :/ Should make a habit of checking the header diffs, as this is not the first time this has happened. > > In liburing.h in 2.3, structures io_uring_cq and io_uring_sq changed > > their sizes. Both of these structures are parts of io_uring structure > > which the main part of the API. Here's the difference: > > > > @@ -43,7 +79,9 @@ > > @@ -56,13 +94,18 @@ > > size_t ring_sz; > > void *ring_ptr; > > - unsigned pad[4]; > > + unsigned ring_mask; > > + unsigned ring_entries; > > + > > + unsigned pad[2]; > > This does not look like it is changing the size actually, - I haven't > noticed it adjusts pad[] accordingly. So this is not the issue here. > > But the end result is the same: samba compiled with liburing 2.2 does > not work with runtime liburing 2.3, and samba compiled with liburing > 2.3 does not work with runtime liburing 2.2. > > I'm just too tired now to dig further. The problem is that this release has deprecated the kring_mask and kring_entries, and does not have fallback code to use them if they are being used by the callers. I'll report this upstream to see how they want to fix this, either with a SOVERSION bump or trying to add dynamic fallback code or similar. For sid, I guess I could bump the affected functions required minimal versions in the symbols file, and then add breaks on the old packages using the old ABI, but meh. :/ Thanks, Guillem
Bug#1023654: liburing 2.3 breaks binary compatibility
On Tue, 08 Nov 2022 15:51:17 +0300 Michael Tokarev wrote: Source: liburing Version: 2.3-1 Severity: grave liburing 2.3 broke binary compatibility without bumping the soname. In liburing.h in 2.3, structures io_uring_cq and io_uring_sq changed their sizes. Both of these structures are parts of io_uring structure which the main part of the API. Here's the difference: @@ -43,7 +79,9 @@ @@ -56,13 +94,18 @@ size_t ring_sz; void *ring_ptr; - unsigned pad[4]; + unsigned ring_mask; + unsigned ring_entries; + + unsigned pad[2]; This does not look like it is changing the size actually, - I haven't noticed it adjusts pad[] accordingly. So this is not the issue here. But the end result is the same: samba compiled with liburing 2.2 does not work with runtime liburing 2.3, and samba compiled with liburing 2.3 does not work with runtime liburing 2.2. I'm just too tired now to dig further. /mjt
Bug#1023654: liburing 2.3 breaks binary compatibility
Source: liburing
Version: 2.3-1
Severity: grave
liburing 2.3 broke binary compatibility without bumping the soname.
In liburing.h in 2.3, structures io_uring_cq and io_uring_sq changed
their sizes. Both of these structures are parts of io_uring structure
which the main part of the API. Here's the difference:
@@ -43,7 +79,9 @@
struct io_uring_sq {
unsigned *khead;
unsigned *ktail;
+ // Deprecated: use `ring_mask` instead of `*kring_mask`
unsigned *kring_mask;
+ // Deprecated: use `ring_entries` instead of `*kring_entries`
unsigned *kring_entries;
unsigned *kflags;
unsigned *kdropped;
@@ -56,13 +94,18 @@
size_t ring_sz;
void *ring_ptr;
- unsigned pad[4];
+ unsigned ring_mask;
+ unsigned ring_entries;
+
+ unsigned pad[2];
};
...
struct io_uring {
struct io_uring_sq sq;
struct io_uring_cq cq;
...
}
So, a program which uses struct io_uring compiled with version 2.2 of the
library is completely incompatible when run with version 2.3 of the library,
and vise versa - since many user-visible members of this structure, even when
manipulated by the inline functions offered by uring.h, are completely
incompatible.
This breaks other software. For example, samba compiled against liburing 2.3
will silently break when liburing 2.2 is used at the run time, and there's no
way for apt/dpkg to tell that liburing2.so upgrade is needed. The same way,
samba compiled against liburing 2.2 breaks when liburing is upgraded to 2.3,
but in a different way.
