From: Paul Gortmaker <paul.gortmaker@windriver.com>
To: linux-kernel@vger.kernel.org
Cc: cgroups@vger.kernel.org, rdunlap@infradead.org,
colin.king@canonical.com,
Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: [PATCH 3/4] cpumask: add a "none" alias to complement "all"
Date: Mon, 9 Nov 2020 23:07:24 -0500 [thread overview]
Message-ID: <20201110040725.1478297-4-paul.gortmaker@windriver.com> (raw)
In-Reply-To: <20201110040725.1478297-1-paul.gortmaker@windriver.com>
With global support for a CPU list alias of "all", it seems to just make
sense to also trivially extend support for an opposite "none" specifier.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
Documentation/admin-guide/kernel-parameters.rst | 6 ++++++
lib/cpumask.c | 5 +++++
2 files changed, 11 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
index ef98ca700946..9e1c4522e1f0 100644
--- a/Documentation/admin-guide/kernel-parameters.rst
+++ b/Documentation/admin-guide/kernel-parameters.rst
@@ -76,6 +76,12 @@ is equivalent to "foo_cpus=0-N" -- where "N" is the numerically last CPU on
the system, thus avoiding looking up the value in "/sys/devices/system/cpu"
in advance on each deployed system.
+ 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 parameter expecting a CPU list.
This document may not be entirely up to date and comprehensive. The command
"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
diff --git a/lib/cpumask.c b/lib/cpumask.c
index 15599cdf5db6..eb8b1c92501e 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -110,6 +110,11 @@ int cpulist_parse(const char *buf, struct cpumask *dstp)
return 0;
}
+ if (!strcmp(buf, "none")) {
+ cpumask_clear(dstp);
+ return 0;
+ }
+
return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpumask_bits);
}
EXPORT_SYMBOL(cpulist_parse);
--
2.25.1
next prev parent reply other threads:[~2020-11-10 4:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-10 4:07 [PATCH v2 0/4] support for global CPU list abbreviations Paul Gortmaker
2020-11-10 4:07 ` [PATCH 1/4] cpumask: un-inline cpulist_parse for SMP; prepare for ascii helpers Paul Gortmaker
2020-11-10 4:07 ` [PATCH 2/4] cpumask: make "all" alias global and not just RCU Paul Gortmaker
2020-11-10 4:07 ` Paul Gortmaker [this message]
2020-11-10 4:07 ` [PATCH 4/4] cpumask: add "last" alias for cpu list specifications Paul Gortmaker
2020-11-10 15:32 ` [PATCH v2 0/4] support for global CPU list abbreviations Paul E. McKenney
2020-11-10 16:09 ` Colin Ian King
-- strict thread matches above, loose matches on Subject: below --
2020-11-08 16:08 [PATCH 0/4] RFC: " Paul Gortmaker
2020-11-08 16:08 ` [PATCH 3/4] cpumask: add a "none" alias to complement "all" Paul Gortmaker
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