On Wed, 29 Jan 2025, Crystal Wood wrote: > On Wed, 2025-01-29 at 16:54 -0500, John Kacur wrote: > > > > On Tue, 28 Jan 2025, Khem Raj wrote: > > > > > glibc 2.41+ has added [1] definitions for sched_setattr and sched_getattr functions > > > and struct sched_attr. Therefore, it needs to be checked for here as well before > > > defining sched_attr > > > > > > Define sched_attr conditionally on SCHED_ATTR_SIZE_VER0 > > > > > > Fixes builds with glibc/trunk > > > > > > [1] https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=21571ca0d70302909cf72707b2a7736cf12190a0;hp=298bc488fdc047da37482f4003023cb9adef78f8 > > > > > > Signed-off-by: Khem Raj <raj.khem@xxxxxxxxx> > > > Cc: Clark Williams <williams@xxxxxxxxxx> > > > Cc: John Kacur <jkacur@xxxxxxxxxx> > > > Cc: rt-users <linux-rt-users@xxxxxxxxxxxxxxx> > > > --- > > > src/include/rt-sched.h | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/src/include/rt-sched.h b/src/include/rt-sched.h > > > index 80171c7..9cf0e3a 100644 > > > --- a/src/include/rt-sched.h > > > +++ b/src/include/rt-sched.h > > > @@ -42,6 +42,8 @@ > > > #define __NR_sched_getattr 275 > > > #endif > > > > > > +/* sched_attr is not defined in glibc < 2.41 */ > > > +#ifndef SCHED_ATTR_SIZE_VER0 > > > struct sched_attr { > > > uint32_t size; > > > uint32_t sched_policy; > > > @@ -68,4 +70,6 @@ int sched_getattr(pid_t pid, > > > unsigned int size, > > > unsigned int flags); > > > > > > +#endif /* SCHED_ATTR_SIZE_VER0 */ > > > + > > > #endif /* __RT_SCHED_H__ */ > > > > > > > > > > Does the following fix your problem? > [snip] > > > +#if ! __GLIBC_PREREQ(2, 41) > > I'm not familiar with the norms surrounding use of this macro, but it's > generally better to test features than versions... what if this feature > gets backported into some distro's earlier-version-numbered glibc? The macro is part of the glibc code in features.h You make a good point about testing the features, but you could also argue that there is no guarantee that the implementation will always have SCHED_ATTR_SIZE_VER0 and that it could break in the future. > > FWIW, it looks like QEMU went with the feature test approach: > https://patchwork.ozlabs.org/project/qemu-devel/patch/20241011054806.1014276-1-raj.khem@xxxxxxxxx/ > https://patchwork.ozlabs.org/project/qemu-devel/patch/20241011193140.1047648-1-raj.khem@xxxxxxxxx/ > Well, that's by the same author who sent this patch. > Also, was that patch posted anywhere? Just wondering if I've still got > problems with email filtering. No, a version of this was sent to me in fedora channels to fix a break in rawhide. The version is more complete than the other patch because it also fixes src/lib/rt-sched.c If this works for folks, lets just use it and move on, it's not worth endlessly hashing out. John Kacur > > -Crystal > > >
