Messages in this thread | | | Date | Sun, 28 Apr 2019 18:40:57 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH 0/4] lib: rework bitmap_parse |
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On Sat, Apr 27, 2019 at 08:29:30PM -0700, Yury Norov wrote: > On top of next-20190418. > > Similarly to recently revisited bitmap_parselist() [1], > bitmap_parse() is ineffective and overcomplicated. This > series reworks it, aligns its interface with bitmap_parselist() > and makes usage simpler. > > The series also adds a test for the function and fixes usage of it > in cpumask_parse() according to new design - drops the calculating > of length of an input string. > > The following users would also consider to drop the length argument, > if possible: > drivers/block/drbd/drbd_main.c:2608 > kernel/padata.c:924 > net/core/net-sysfs.c:726 > net/core/net-sysfs.c:1309 > net/core/net-sysfs.c:1391 > > bitmap_parse() takes the array of numbers to be put into the map in > the BE order which is reversed to the natural LE order for bitmaps. > For example, to construct bitmap containing a bit on the position 42, > we have to put a line '400,0'. Current implementation reads chunk > one by one from the beginning ('400' before '0') and makes bitmap > shift after each successful parse. It makes the complexity of the > whole process as O(n^2). We can do it in reverse direction ('0' > before '400') and avoid shifting, but it requires reverse parsing > helpers.
Shouldn't test ceases pass on existing code base? I would rather start series with enabling tests and then we will have a proof that before and after at least tests have not been broken.
> > Tested on arm64 and BE mips. > > [1] https://lkml.org/lkml/2019/4/16/66 > > Yury Norov (6): > lib/string: add strnchrnul() > bitops: more BITS_TO_* macros > lib/bitmap: make bitmap_parse_user a wrapper on bitmap_parse > lib: rework bitmap_parse() > lib: add test for bitmap_parse() > cpumask: don't calculate length of the input string > > include/linux/bitmap.h | 8 +- > include/linux/bitops.h | 3 + > include/linux/cpumask.h | 4 +- > include/linux/string.h | 3 + > lib/bitmap.c | 197 +++++++++++++++++------------------ > lib/string.c | 20 ++++ > lib/test_bitmap.c | 102 +++++++++++++++++- > tools/include/linux/bitops.h | 9 +- > 8 files changed, 230 insertions(+), 116 deletions(-) > > -- > 2.17.1 >
-- With Best Regards, Andy Shevchenko
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