(12/18/11 5:44 PM), David Rientjes wrote:
On Sun, 18 Dec 2011, Ryota Ozaki wrote:
/sys/devices/system/node/{online,possible} involve a garbage byte
because print_nodes_state returns content size + 1. To fix the bug,
the patch changes the use of cpuset_sprintf_cpulist to follow the
use at other places, which is clearer and safer.
It's not a garbage byte, sysdev files use a buffer created with
get_zeroed_page(), so extra byte is guaranteed to be zero since
nodelist_scnprintf() won't write to it. So the issue here is that
print_nodes_state() returns a size that is off by one according to
ISO C99 although it won't cause a problem in practice.
This bug was introduced since v2.6.24.
It's not a bug, the result of a 4-node system would be "0-3\n\0" and
returns 5 correctly. You can verify this very simply with strace.
Usually, /sys files don't output trailing '¥0'. And, '¥0' is not regular
io friendly. So I can imagine some careless programmer think it is
garbage. Is there any benefit to show trailing '¥0'?
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