From: tip-bot for Ingo Molnar <mingo@elte.hu>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com,
torvalds@linux-foundation.org, jeff@garzik.org,
tglx@linutronix.de, mingo@elte.hu
Subject: [tip:sched/core] sched: properly define the sched_group::cpumask and sched_domain::span fields
Date: Tue, 19 May 2009 08:31:00 GMT [thread overview]
Message-ID: <tip-4200efd9acda4accf24640f1e77d24fdcdb524df@git.kernel.org> (raw)
In-Reply-To: <alpine.LFD.2.01.0905180850110.3301@localhost.localdomain>
Commit-ID: 4200efd9acda4accf24640f1e77d24fdcdb524df
Gitweb: http://git.kernel.org/tip/4200efd9acda4accf24640f1e77d24fdcdb524df
Author: Ingo Molnar <mingo@elte.hu>
AuthorDate: Tue, 19 May 2009 09:22:19 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 19 May 2009 09:22:19 +0200
sched: properly define the sched_group::cpumask and sched_domain::span fields
Properly document the variable-size structure tricks we are doing
wrt. struct sched_group and sched_domain, and use the field[0] GCC
extension instead of defining a vla array.
Dont use unions for this, as pointed out by Linus.
[ Impact: cleanup, un-confuse Sparse and LLVM ]
Reported-by: Jeff Garzik <jeff@garzik.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <alpine.LFD.2.01.0905180850110.3301@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/sched.h | 25 ++++++++++++++++++++++---
kernel/sched.c | 5 +++--
2 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index de7b3b2..dbb1043 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -839,7 +839,17 @@ struct sched_group {
*/
u32 reciprocal_cpu_power;
- unsigned long cpumask[];
+ /*
+ * The CPUs this group covers.
+ *
+ * NOTE: this field is variable length. (Allocated dynamically
+ * by attaching extra space to the end of the structure,
+ * depending on how many CPUs the kernel has booted up with)
+ *
+ * It is also be embedded into static data structures at build
+ * time. (See 'struct static_sched_group' in kernel/sched.c)
+ */
+ unsigned long cpumask[0];
};
static inline struct cpumask *sched_group_cpus(struct sched_group *sg)
@@ -925,8 +935,17 @@ struct sched_domain {
char *name;
#endif
- /* span of all CPUs in this domain */
- unsigned long span[];
+ /*
+ * Span of all CPUs in this domain.
+ *
+ * NOTE: this field is variable length. (Allocated dynamically
+ * by attaching extra space to the end of the structure,
+ * depending on how many CPUs the kernel has booted up with)
+ *
+ * It is also be embedded into static data structures at build
+ * time. (See 'struct static_sched_domain' in kernel/sched.c)
+ */
+ unsigned long span[0];
};
static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
diff --git a/kernel/sched.c b/kernel/sched.c
index 497c09b..228acae 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7948,8 +7948,9 @@ int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
/*
* The cpus mask in sched_group and sched_domain hangs off the end.
- * FIXME: use cpumask_var_t or dynamic percpu alloc to avoid wasting space
- * for nr_cpu_ids < CONFIG_NR_CPUS.
+ *
+ * ( See the the comments in include/linux/sched.h:struct sched_group
+ * and struct sched_domain. )
*/
struct static_sched_group {
struct sched_group sg;
next prev parent reply other threads:[~2009-05-19 8:32 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-18 14:27 [GIT PULL] scheduler fixes Ingo Molnar
2009-05-18 16:13 ` Linus Torvalds
2009-05-18 16:49 ` Ingo Molnar
2009-05-18 16:58 ` Linus Torvalds
2009-05-18 17:09 ` Ingo Molnar
2009-05-18 19:03 ` Ingo Molnar
2009-05-18 19:16 ` Linus Torvalds
2009-05-18 20:20 ` Ingo Molnar
2009-05-18 22:06 ` Linus Torvalds
2009-05-19 12:27 ` Rusty Russell
2009-05-24 16:13 ` Pekka J Enberg
2009-05-24 18:18 ` Linus Torvalds
2009-05-24 19:13 ` Pekka Enberg
2009-05-25 5:16 ` Benjamin Herrenschmidt
2009-05-24 18:34 ` Yinghai Lu
2009-05-24 19:15 ` Pekka Enberg
2009-05-25 2:53 ` Ingo Molnar
2009-05-25 4:45 ` Yinghai Lu
2009-05-25 5:15 ` Ingo Molnar
2009-05-25 5:54 ` Yinghai Lu
2009-05-25 8:47 ` Pekka J Enberg
2009-05-25 11:25 ` Nick Piggin
2009-05-25 11:37 ` Pekka Enberg
2009-05-25 11:41 ` Nick Piggin
2009-05-25 11:44 ` Pekka J Enberg
2009-05-25 15:01 ` Matt Mackall
2009-05-25 16:39 ` Linus Torvalds
2009-05-25 18:39 ` Pekka Enberg
2009-05-25 19:14 ` Linus Torvalds
2009-05-25 19:13 ` Pekka Enberg
2009-05-26 1:50 ` Yinghai Lu
2009-05-26 7:38 ` Nick Piggin
2009-05-28 12:06 ` Pekka Enberg
2009-05-28 12:12 ` Nick Piggin
2009-05-28 12:24 ` Pekka Enberg
2009-05-26 7:33 ` Nick Piggin
2009-05-25 12:04 ` Pekka J Enberg
2009-05-25 12:12 ` Nick Piggin
2009-05-25 14:55 ` Matt Mackall
2009-05-25 14:58 ` Pekka Enberg
2009-05-26 17:19 ` Christoph Lameter
2009-05-28 12:14 ` Pekka Enberg
2009-05-26 14:27 ` Christoph Lameter
2009-05-25 4:52 ` H. Peter Anvin
2009-05-25 5:05 ` Ingo Molnar
2009-05-25 5:13 ` Yinghai Lu
2009-05-25 5:19 ` Benjamin Herrenschmidt
2009-05-25 7:16 ` Rusty Russell
[not found] ` <4A12E759.6040806@kernel.org>
[not found] ` <20090520071900.GB11952@elte.hu>
2009-05-20 7:37 ` [PATCH] x86: enable_update_mptable should MACRO Yinghai Lu
2009-05-28 0:00 ` [tip:irq/numa] x86: enable_update_mptable should be a macro tip-bot for Yinghai Lu
2009-05-19 8:31 ` tip-bot for Ingo Molnar [this message]
2009-05-18 16:55 ` [GIT PULL, v2] scheduler fixes Ingo Molnar
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