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From: Mike Travis <travis@sgi.com>
To: Ingo Molnar <mingo@elte.hu>, Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <andi@firstfloor.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	davej@codemonkey.org.uk, David Miller <davem@davemloft.net>,
	Eric Dumazet <dada1@cosmosbay.com>,
	Jack Steiner <steiner@sgi.com>,
	Jeremy Fitzhardinge <jeremy@goop.org>, Jes Sorensen <jes@sgi.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	peterz@infradead.org, Thomas Gleixner <tglx@linutronix.de>,
	Yinghai Lu <yhlu.kernel@gmail.com>,
	IA64 <linux-ia64@vger.kernel.org>,
	PowerPC <linuxppc-dev@ozlabs.org>,
	S390 <linux-s390@vger.kernel.org>,
	SPARC <sparclinux@vger.kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 10/35] cpumask: introduce cpumask_var_t for local cpumask vars
Date: Mon, 20 Oct 2008 10:03:29 -0700	[thread overview]
Message-ID: <20081020170320.986214000@polaris-admin.engr.sgi.com> (raw)
In-Reply-To: <20081020170319.539427000@polaris-admin.engr.sgi.com>

[-- Attachment #1: cpumask:cpumask_var_t.patch --]
[-- Type: text/plain, Size: 2789 bytes --]

We want to move cpumasks off the stack: no local decls, no passing by
copy.  Linus suggested we use the array-or-pointer trick for on-stack
vars; we introduce a new cpumask_var_t for this.

Rather than pick an arbitrary limit, I chose a new config option so
arch maintainers can decide where their threshold is.

From: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
---
 include/linux/cpumask.h |   36 ++++++++++++++++++++++++++++++++++++
 lib/cpumask.c           |   31 +++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

--- test-compile.orig/include/linux/cpumask.h
+++ test-compile/include/linux/cpumask.h
@@ -485,6 +485,42 @@ int __next_cpu_nr(int n, const cpumask_t
 #endif /* NR_CPUS > 64 */
 
 /*
+ * cpumask_var_t: struct cpumask for stack usage.
+ *
+ * Oh, the wicked games we play!  In order to make kernel coding a
+ * little more difficult, we typedef cpumask_var_t to an array or a
+ * pointer: doing &mask on an array is a noop, so it still works.
+ *
+ * ie.
+ *	cpumask_var_t tmpmask;
+ *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
+ *		return -ENOMEM;
+ *
+ *	  ... use 'tmpmask' like a normal struct cpumask * ...
+ *
+ *	free_cpumask_var(tmpmask);
+ */
+#ifdef CONFIG_CPUMASK_OFFSTACK
+typedef struct cpumask *cpumask_var_t;
+
+bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
+void free_cpumask_var(cpumask_var_t mask);
+
+#else
+typedef struct cpumask cpumask_var_t[1];
+
+static inline bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+{
+	return true;
+}
+
+static inline void free_cpumask_var(cpumask_var_t mask)
+{
+}
+
+#endif /* CONFIG_CPUMASK_OFFSTACK */
+
+/*
  * The following particular system cpumasks and operations manage
  * possible, present, active and online cpus.  Each of them is a fixed size
  * bitmap of size NR_CPUS.
--- test-compile.orig/lib/cpumask.c
+++ test-compile/lib/cpumask.c
@@ -43,3 +43,34 @@ int __any_online_cpu(const cpumask_t *ma
 	return cpu;
 }
 EXPORT_SYMBOL(__any_online_cpu);
+
+/* These are not inline because of header tangles. */
+#ifdef CONFIG_CPUMASK_OFFSTACK
+bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+{
+	if (likely(slab_is_available()))
+		*mask = kmalloc(BITS_TO_LONGS(nr_cpu_ids)*sizeof(long), flags);
+	else {
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+		printk(KERN_ERR
+			"=> alloc_cpumask_var: kmalloc not available!\n");
+		dump_stack();
+#endif
+		*mask = NULL;
+	}
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+	if (!*mask) {
+		printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
+		dump_stack();
+	}
+#endif
+	return *mask != NULL;
+}
+EXPORT_SYMBOL(alloc_cpumask_var);
+
+void free_cpumask_var(cpumask_var_t mask)
+{
+	kfree(mask);
+}
+EXPORT_SYMBOL(free_cpumask_var);
+#endif

-- 

  parent reply	other threads:[~2008-10-20 17:13 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-20 17:03 [PATCH 00/35] cpumask: Replace cpumask_t with struct cpumask Mike Travis
2008-10-20 17:03 ` [PATCH 01/35] x86: clean up speedctep-centrino and reduce cpumask_t usage Mike Travis
2008-10-21  0:09   ` Stephen Rothwell
2008-10-21 12:28     ` Mike Travis
2008-10-20 17:03 ` [PATCH 02/35] cpumask: remove min from first_cpu/next_cpu Mike Travis
2008-10-20 17:03 ` [PATCH 03/35] cpumask: add for_each_cpu_mask_and function Mike Travis
2008-10-20 17:03 ` [PATCH 04/35] x86 smp: modify send_IPI_mask interface to accept cpumask_t pointers Mike Travis
2008-10-20 17:03 ` [PATCH 05/35] sched: Reduce stack size requirements in kernel/sched.c Mike Travis
2008-10-20 17:03 ` [PATCH 06/35] cpumask: introduce struct cpumask Mike Travis
2008-10-20 17:03 ` [PATCH 07/35] cpumask: change cpumask_scnprintf, cpumask_parse_user, cpulist_parse, and cpulist_scnprintf to take pointers Mike Travis
2008-10-20 17:03 ` [PATCH 08/35] cpumask: cpumask_size() Mike Travis
2008-10-20 17:03 ` [PATCH 09/35] cpumask: add cpumask_copy() Mike Travis
2008-10-20 17:03 ` Mike Travis [this message]
2008-10-20 17:03 ` [PATCH 11/35] x86: enable MAXSMP Mike Travis
2008-10-20 17:03 ` [PATCH 12/35] cpumask: make CONFIG_NR_CPUS always valid Mike Travis
2008-10-20 17:03 ` [PATCH 13/35] cpumask: use setup_nr_cpu_ids() instead of direct assignment Mike Travis
2008-10-20 17:03 ` [PATCH 14/35] cpumask: make nr_cpu_ids valid in all configurations Mike Travis
2008-10-20 17:03 ` [PATCH 15/35] cpumask: prepare for iterators to only go to nr_cpu_ids Mike Travis
2008-10-20 17:03 ` [PATCH 16/35] percpu: fix percpu accessors to potentially !cpu_possible() cpus Mike Travis
2008-10-20 17:03 ` [PATCH 17/35] cpumask: make nr_cpu_ids the actual limit on bitmap size Mike Travis
2008-10-20 17:03 ` [PATCH 18/35] cpumask: add nr_cpumask_bits Mike Travis
2008-10-21 12:26   ` Rusty Russell
2008-10-21 13:53     ` Mike Travis
2008-10-20 17:03 ` [PATCH 19/35] cpumask: use cpumask_bits() everywhere Mike Travis
2008-10-20 17:03 ` [PATCH 20/35] cpumask: cpumask_of(): cpumask_of_cpu() which returns a pointer Mike Travis
2008-10-20 17:03 ` [PATCH 21/35] cpumask: for_each_cpu(): for_each_cpu_mask which takes " Mike Travis
2008-10-20 17:03 ` [PATCH 22/35] cpumask: cpumask_first/cpumask_next Mike Travis
2008-10-20 17:03 ` [PATCH 23/35] cpumask: deprecate any_online_cpu() in favour of cpumask_any/cpumask_any_and Mike Travis
2008-10-20 17:03 ` [PATCH 24/35] cpumask: cpumask_any_but() Mike Travis
2008-10-20 17:03 ` [PATCH 25/35] cpumask: Deprecate CPUMASK_ALLOC etc in favor of cpumask_var_t Mike Travis
2008-10-20 17:03 ` [PATCH 26/35] cpumask: get rid of boutique sched.c allocations, use cpumask_var_t Mike Travis
2008-10-20 17:03 ` [PATCH 27/35] cpumask: to_cpumask() Mike Travis
2008-10-20 17:03 ` [PATCH 28/35] cpumask: accessors to manipulate possible/present/online/active maps Mike Travis
2008-10-20 17:03 ` [PATCH 29/35] cpumask: Use accessors code Mike Travis
2008-10-20 17:03 ` [PATCH 30/35] cpumask: CONFIG_BITS_ALL, CONFIG_BITS_NONE and CONFIG_BITS_CPU0 Mike Travis
2008-10-20 17:03 ` [PATCH 31/35] cpumask: switch over to cpu_online/possible/active/present_mask Mike Travis
2008-10-20 17:03 ` [PATCH 32/35] cpumask: cpu_all_mask and cpu_none_mask Mike Travis
2008-10-20 17:03 ` [PATCH 33/35] cpumask: reorder header to minimize separate #ifdefs Mike Travis
2008-10-20 17:03 ` [PATCH 34/35] cpumask: debug options for cpumasks Mike Travis
2008-10-20 17:03 ` [PATCH 35/35] cpumask: smp_call_function_many() Mike Travis

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