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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-05-19 09:37:41 +0900
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-19 11:48:18 -0700
commitfa9dc265ace9774e62f0e31108e5f47911124bda (patch)
treef5230efca0ccf0cfec7690a6c45209cff938d740 /kernel/compat.c
parentcf77e988ddfc7f047ac1ddc72cadb5eee7e09293 (diff)
downloadlinux-sh-fa9dc265ace9774e62f0e31108e5f47911124bda.tar.gz
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 'kernel/compat.c')
-rw-r--r--kernel/compat.c25
1 files changed, 11 insertions, 14 deletions
diff --git a/kernel/compat.c b/kernel/compat.c
index 7f40e9275fd9..5adab05a3172 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -495,29 +495,26 @@ asmlinkage long compat_sys_sched_getaffinity(compat_pid_t pid, unsigned int len,
{
int ret;
cpumask_var_t mask;
- unsigned long *k;
- unsigned int min_length = cpumask_size();
-
- if (nr_cpu_ids <= BITS_PER_COMPAT_LONG)
- min_length = sizeof(compat_ulong_t);
- if (len < min_length)
+ if ((len * BITS_PER_BYTE) < nr_cpu_ids)
+ return -EINVAL;
+ if (len & (sizeof(compat_ulong_t)-1))
return -EINVAL;
if (!alloc_cpumask_var(&mask, GFP_KERNEL))
return -ENOMEM;
ret = sched_getaffinity(pid, mask);
- if (ret < 0)
- goto out;
+ if (ret == 0) {
+ size_t retlen = min_t(size_t, len, cpumask_size());
- k = cpumask_bits(mask);
- ret = compat_put_bitmap(user_mask_ptr, k, min_length * 8);
- if (ret == 0)
- ret = min_length;
-
-out:
+ if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
+ ret = -EFAULT;
+ else
+ ret = retlen;
+ }
free_cpumask_var(mask);
+
return ret;
}