Messages in this thread | | | Date | Tue, 7 May 2019 14:04:21 -0700 | From | Yury Norov <> | Subject | Re: [PATCH 0/7] lib: rework bitmap_parse |
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On Tue, Apr 30, 2019 at 06:06:29PM -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. > > Tested on arm64 and BE mips.
Any comments?
> v1: https://lkml.org/lkml/2019/4/27/597 > v2: > - strnchrnul() signature and description changed, ifdeffery and > exporting removed; > - test split for better demonstration of before/after changes; > - minor naming and formatting issues fixed. > > [1] https://lkml.org/lkml/2019/4/16/66 > > Yury Norov (7): > lib/string: add strnchrnul() > bitops: more BITS_TO_* macros > lib: add test for bitmap_parse() > lib: make bitmap_parse_user a wrapper on bitmap_parse > lib: rework bitmap_parse() > lib: new testcases for bitmap_parse{_user} > cpumask: don't calculate length of the input string > > include/linux/bitmap.h | 8 +- > include/linux/bitops.h | 5 +- > include/linux/cpumask.h | 4 +- > include/linux/string.h | 1 + > lib/bitmap.c | 197 +++++++++++++++++------------------ > lib/string.c | 17 +++ > lib/test_bitmap.c | 102 +++++++++++++++++- > tools/include/linux/bitops.h | 9 +- > 8 files changed, 226 insertions(+), 117 deletions(-) > > -- > 2.17.1
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