From: paulmck@kernel.org
To: linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, yury.norov@gmail.com, kernel-team@fb.com,
Paul Gortmaker <paul.gortmaker@windriver.com>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH RFC cpumask 3/5] cpumask: Add a "none" alias to complement "all"
Date: Tue, 5 Jan 2021 16:49:54 -0800 [thread overview]
Message-ID: <20210106004956.11961-3-paulmck@kernel.org> (raw)
In-Reply-To: <20210106004850.GA11682@paulmck-ThinkPad-P72>
From: Paul Gortmaker <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>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
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 cdf4e81..7dd1224 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 9f8ff72..7fbcab8 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);
--
2.9.5
next prev parent reply other threads:[~2021-01-06 0:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 0:48 [PATCH RFC cpumask] Allow "all", "none", and "last" in cpumask strings Paul E. McKenney
2021-01-06 0:49 ` [PATCH RFC cpumask 1/5] cpumask: Un-inline cpulist_parse for SMP; prepare for ascii helpers paulmck
2021-01-06 0:49 ` [PATCH RFC cpumask 2/5] cpumask: Make "all" alias global and not just RCU paulmck
2021-01-06 6:32 ` Yury Norov
2021-01-06 0:49 ` paulmck [this message]
2021-01-06 6:59 ` [PATCH RFC cpumask 3/5] cpumask: Add a "none" alias to complement "all" Yury Norov
2021-01-06 0:49 ` [PATCH RFC cpumask 4/5] cpumask: Add "last" alias for cpu list specifications paulmck
2021-01-06 8:41 ` Yury Norov
2021-01-06 9:49 ` Peter Zijlstra
2021-01-06 17:45 ` Paul Gortmaker
2021-01-06 21:16 ` Yury Norov
2021-01-07 14:18 ` Peter Zijlstra
2021-01-07 14:47 ` Paul E. McKenney
2021-01-07 14:59 ` Peter Zijlstra
2021-01-07 15:32 ` Paul E. McKenney
2021-01-07 15:05 ` Paul E. McKenney
2021-01-06 0:49 ` [PATCH RFC cpumask 5/5] rcutorture: Use "all" and "last" in "nohz_full" and "rcu_nocbs" paulmck
2021-01-06 8:49 ` [PATCH RFC cpumask] Allow "all", "none", and "last" in cpumask strings Yury Norov
2021-01-21 7:11 ` Yury Norov
2021-01-21 16:57 ` Paul E. McKenney
2021-01-21 21:39 ` Paul E. McKenney
2021-01-21 22:42 ` Paul Gortmaker
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