Messages in this thread | | | From | "Chen, Kenneth W" <> | Subject | RE: [patch] remove redundant iov segment check | Date | Mon, 4 Dec 2006 11:45:28 -0800 |
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Zach Brown wrote on Monday, December 04, 2006 11:19 AM > On Dec 4, 2006, at 8:26 AM, Chen, Kenneth W wrote: > > > The access_ok() and negative length check on each iov segment in > > function > > generic_file_aio_read/write are redundant. They are all already > > checked > > before calling down to these low level generic functions. > > ... > > > So it's not possible to call down to generic_file_aio_read/write > > with invalid > > iov segment. > > Well, generic_file_aio_{read,write}() are exported to modules, so > anything's *possible*. :) > > This change makes me nervous because it relies on our ability to > audit all code paths to ensure that it's correct. It'd be nice if > the code enforced the rules.
Maybe we should create another internal generic_file_aio_read/write for in-core function? fs/read_write.c and fs/aio.c are not module-able and the check is already there. For external module, we can do the check and then calls down to the internal one.
I hate to see iov is being walked multiple times .... And this is part of my effort to bring back O_DIRECT performance compares to a 3-years old vendor kernel based on 2.4 kernel.
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