diff options
author | KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> | 2010-05-19 09:37:41 +0900 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-19 11:48:18 -0700 |
commit | fa9dc265ace9774e62f0e31108e5f47911124bda (patch) | |
tree | f5230efca0ccf0cfec7690a6c45209cff938d740 /arch/arm/plat-samsung/include/plat/dma.h | |
parent | cf77e988ddfc7f047ac1ddc72cadb5eee7e09293 (diff) |
cpumask: fix compat getaffinity
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.
On NUMA systems with less than 32 possibly CPUs, the current
compat_sys_sched_getaffinity now returns '4' instead of the actual
NR_CPUS/8, which makes libnuma bail out when parsing the cpumap.
The libnuma call sched_getaffinity(0, bitmap, 4096) at first. It mean
the libnuma expect the return value of sched_getaffinity() is either len
argument or NR_CPUS. But it doesn't expect to return nr_cpu_ids.
Strictly speaking, userland requirement are
1) Glibc assume the return value mean the lengh of initialized
of mask argument. E.g. if sched_getaffinity(1024) return 128,
glibc make zero fill rest 896 byte.
2) Libnuma assume the return value can be used to guess NR_CPUS
in kernel. It assume len-arg<NR_CPUS makes -EINVAL. But
it try len=4096 at first and 4096 is always bigger than
NR_CPUS. Then, if we remove strange min_length normalization,
we never hit -EINVAL case.
sched_getaffinity() already solved this issue. This patch adapts
compat_sys_sched_getaffinity() to match the non-compat case.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Ken Werner <ken.werner@web.de>
Cc: stable@kernel.org
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/arm/plat-samsung/include/plat/dma.h')
0 files changed, 0 insertions, 0 deletions