From: "tip-bot2 for Yury Norov" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Yury Norov <yury.norov@gmail.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: core/rcu] bitmap_parse: Support 'all' semantics
Date: Wed, 30 Jun 2021 13:48:03 -0000 [thread overview]
Message-ID: <162506088324.395.4488352989288920101.tip-bot2@tip-bot2> (raw)
The following commit has been merged into the core/rcu branch of tip:
Commit-ID: b18def121f077857ccf92fc620366e19850bc297
Gitweb: https://git.kernel.org/tip/b18def121f077857ccf92fc620366e19850bc297
Author: Yury Norov <yury.norov@gmail.com>
AuthorDate: Tue, 20 Apr 2021 20:13:25 -07:00
Committer: Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Mon, 10 May 2021 15:38:20 -07:00
bitmap_parse: Support 'all' semantics
RCU code supports an 'all' group as a special case when parsing rcu_nocbs
parameter. This patch moves the 'all' support to the core bitmap_parse
code, so that all bitmap users can enjoy this extension.
Moving 'all' parsing to a bitmap_parse level also allows users to pass
patterns together with 'all' in regular group:pattern format, for example,
"rcu_nocbs=all:1/2" would offload all the even-numbered CPUs regardless
of the number of CPUs on the system.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
Documentation/admin-guide/kernel-parameters.rst | 5 +++++
lib/bitmap.c | 9 +++++++++
lib/test_bitmap.c | 7 +++++++
3 files changed, 21 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
index 3996b54..01ba293 100644
--- a/Documentation/admin-guide/kernel-parameters.rst
+++ b/Documentation/admin-guide/kernel-parameters.rst
@@ -76,6 +76,11 @@ to change, such as less cores in the CPU list, then N and any ranges using N
will also change. Use the same on a small 4 core system, and "16-N" becomes
"16-3" and now the same boot input will be flagged as invalid (start > end).
+The special case-tolerant group name "all" has a meaning of selecting all CPUs,
+so that "nohz_full=all" is the equivalent of "nohz_full=0-N".
+
+The semantics of "N" and "all" is supported on a level of bitmaps and holds for
+all users of bitmap_parse().
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/bitmap.c b/lib/bitmap.c
index 74ceb02..6e29b2a 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -581,6 +581,14 @@ static const char *bitmap_parse_region(const char *str, struct region *r)
{
unsigned int lastbit = r->nbits - 1;
+ if (!strncasecmp(str, "all", 3)) {
+ r->start = 0;
+ r->end = lastbit;
+ str += 3;
+
+ goto check_pattern;
+ }
+
str = bitmap_getnum(str, &r->start, lastbit);
if (IS_ERR(str))
return str;
@@ -595,6 +603,7 @@ static const char *bitmap_parse_region(const char *str, struct region *r)
if (IS_ERR(str))
return str;
+check_pattern:
if (end_of_region(*str))
goto no_pattern;
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 9cd5755..4ea73f5 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -366,6 +366,13 @@ static const struct test_bitmap_parselist parselist_tests[] __initconst = {
{0, "0-31:1/3,1-31:1/3,2-31:1/3", &exp1[8 * step], 32, 0},
{0, "1-10:8/12,8-31:24/29,0-31:0/3", &exp1[9 * step], 32, 0},
+ {0, "all", &exp1[8 * step], 32, 0},
+ {0, "0, 1, all, ", &exp1[8 * step], 32, 0},
+ {0, "all:1/2", &exp1[4 * step], 32, 0},
+ {0, "ALL:1/2", &exp1[4 * step], 32, 0},
+ {-EINVAL, "al", NULL, 8, 0},
+ {-EINVAL, "alll", NULL, 8, 0},
+
{-EINVAL, "-1", NULL, 8, 0},
{-EINVAL, "-0", NULL, 8, 0},
{-EINVAL, "10-1", NULL, 8, 0},
reply other threads:[~2021-06-30 13:52 UTC|newest]
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