Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [stable] cpumask: fix compat getaffinity | Date | Tue, 11 May 2010 15:21:52 +0930 |
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On Tue, 11 May 2010 12:43:54 pm Greg KH wrote: > On Tue, May 11, 2010 at 10:47:03AM +0900, KOSAKI Motohiro wrote: > > > How's this? > > > > > > cpumask: use nr_cpu_ids for printing and parsing cpumasks > > > > > > Commit a45185d2d "cpumask: convert kernel/compat.c" broke > > > libnuma, which abuses sched_getaffinity to find out NR_CPUS > > > in order to parse /sys/devices/system/node/node*/cpumap. > > > > > > However, the result now returned reflects nr_cpu_ids, and > > > cpumask_scnprintf et al. use nr_cpumask_bits which is NR_CPUS (for > > > CONFIG_CPUMASK_OFFSTACK=n) or nr_cpu_ids (for > > > CONFIG_CPUMASK_OFFSTACK=y). > > > > > > We should use nr_cpu_ids consistently. > > > > > > Reported-by: Arnd Bergmann <arnd@arndb.de> > > > Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> > > > Cc: stable@kernel.org > > > > Well, This patch seems to have ABI change. please don't send abi-change to -stable. > > Why? There is no such thing as a "stable" internal abi in the kernel, > and that includes the -stable kernel releases.
He's referring to the change in sysfs output. However, the ABI involved is already defined to be robust against change of NR_CPUS, so changing it to nr_cpu_ids is OK.
Of course, if libnuma weren't abusing the ABI, this change wouldn't be necessary :(
Cheers, Rusty.
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