[Re: [PATCH 1/3] lib: add "all" and "none" as valid ranges to bitmap_parselist()] On 21/01/2021 (Thu 16:07) Yury Norov wrote:
> On Thu, Jan 21, 2021 at 2:34 PM Paul Gortmaker > <[email protected]> wrote: > > > > The use of "all" was originally RCU specific - I'd pushed it down to > > being used for any CPU lists -- then Yuri suggested pushing it down > > further to be used by any bitmap, which is done here. > > > > As a trivial one line extension, we also accept the inverse "none" > > as a valid alias. > > > > Cc: Yury Norov <[email protected]> > > Cc: Peter Zijlstra <[email protected]> > > Cc: "Paul E. McKenney" <[email protected]> > > Signed-off-by: Paul Gortmaker <[email protected]> > > --- > > Documentation/admin-guide/kernel-parameters.rst | 11 +++++++++++ > > lib/bitmap.c | 9 +++++++++ > > 2 files changed, 20 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.rst > > b/Documentation/admin-guide/kernel-parameters.rst > > index 682ab28b5c94..5e080080b058 100644 > > --- a/Documentation/admin-guide/kernel-parameters.rst > > +++ b/Documentation/admin-guide/kernel-parameters.rst > > @@ -68,7 +68,18 @@ For example one can add to the command line following > > parameter: > > > > where the final item represents CPUs 100,101,125,126,150,151,... > > > > +The following convenience aliases are also accepted and used: > > > > + foo_cpus=all > > + > > +will provide an full/all-set cpu mask for the associated boot argument. > > + > > + foo_cpus=none > > + > > +will provide an empty/cleared cpu mask for the associated boot argument. > > + > > +Note that "all" and "none" are not necessarily valid/sensible input values > > +for each available boot parameter expecting a CPU list. > > My question from v1 is still there: what about the line like > "none,all", ok ",all," Apologies - I must have overlooked that somehow. Let me address it now. > or similar? If it's not legal, it should be mentioned in the comment, OK, it is not legal. So if desired, I can do this in the code... - * Optionally the self-descriptive "all" or "none" can be used. + * Optionally the self-descriptive stand alone "all" or "none" can be used. ...and a similar "stand alone" addition in kernel-parameters.rst above? > if it is legal, > the corresponding code should go to bitmap_parse_region(), just like for "N". Non-standalone is not legal. The strcmp ensures the "all" or "none" are stand-alone. And as can be seen in the testing below, any attempt to combine them with commas or ranges or repeated instances is -EINVAL. (And I'll look at adding such tests to bitmap_test.c as requested.) > My personal preference is the latter option. I'm a bit confused as to the value in adding code for supporting things like ",all,none,all,,none" and then having to define some policy, like "last processed takes precedence" or similar. A strict stand-alone "all" or "none" and everything else as -EINVAL as per below seems logical. Maybe I'm missing something and you can elaborate? Thanks Paul. -- root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo all,none,all > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo none,all > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo all,all > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo all, > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo all > cpuset.cpus root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo ,none > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo none > cpuset.cpus root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo 1,3,5,7,9,11,13,15 > cpuset.cpus root@hackbox:/sys/fs/cgroup/cpuset/foo# cat cpuset.cpus 1,3,5,7,9,11,13,15 root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo 1,3,5,7,9,11,13,all > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo# /bin/echo none,3,5,7,9,11,13,15 > cpuset.cpus /bin/echo: write error: Invalid argument root@hackbox:/sys/fs/cgroup/cpuset/foo#
