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Commit 9b130ad5 authored Sep 08, 2017 by Alexey Dobriyan Committed by Linus Torvalds Sep 08, 2017

treewide: make "nr_cpu_ids" unsigned

First, number of CPUs can't be negative number.

Second, different signnnedness leads to suboptimal code in the following
cases:

1)
	kmalloc(nr_cpu_ids * sizeof(X));

"int" has to be sign extended to size_t.

2)
	while (loff_t *pos < nr_cpu_ids)

MOVSXD is 1 byte longed than the same MOV.

Other cases exist as well. Basically compiler is told that nr_cpu_ids
can't be negative which can't be deduced if it is "int".

Code savings on allyesconfig kernel: -3KB

	add/remove: 0/0 grow/shrink: 25/264 up/down: 261/-3631 (-3370)
	function                                     old     new   delta
	coretemp_cpu_online                          450     512     +62
	rcu_init_one                                1234    1272     +38
	pci_device_probe                             374     399     +25

				...

	pgdat_reclaimable_pages                      628     556     -72
	select_fallback_rq                           446     369     -77
	task_numa_find_cpu                          1923    1807    -116

Link: http://lkml.kernel.org/r/20170819114959.GA30580@avx2


Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ac036f95

arch/arm64/kernel/smp.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -690,7 +690,7 @@ void __init smp_init_cpus(void)
	acpi_parse_gic_cpu_interface, 0);		acpi_parse_gic_cpu_interface, 0);

	if (cpu_count > nr_cpu_ids)		if (cpu_count > nr_cpu_ids)
	pr_warn("Number of cores (%d) exceeds configured maximum of %d - clipping\n",		pr_warn("Number of cores (%d) exceeds configured maximum of %u - clipping\n",
	cpu_count, nr_cpu_ids);		cpu_count, nr_cpu_ids);

	if (!bootcpu_valid) {		if (!bootcpu_valid) {

arch/powerpc/kernel/paca.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -224,7 +224,7 @@ void __init allocate_pacas(void)
	paca = __va(memblock_alloc_base(paca_size, PAGE_SIZE, limit));		paca = __va(memblock_alloc_base(paca_size, PAGE_SIZE, limit));
	memset(paca, 0, paca_size);		memset(paca, 0, paca_size);

	printk(KERN_DEBUG "Allocated %u bytes for %d pacas at %p\n",		printk(KERN_DEBUG "Allocated %u bytes for %u pacas at %p\n",
	paca_size, nr_cpu_ids, paca);		paca_size, nr_cpu_ids, paca);

	allocate_lppacas(nr_cpu_ids, limit);		allocate_lppacas(nr_cpu_ids, limit);

arch/powerpc/kernel/setup-common.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -551,7 +551,7 @@ void __init smp_setup_cpu_maps(void)
	if (maxcpus > nr_cpu_ids) {		if (maxcpus > nr_cpu_ids) {
	printk(KERN_WARNING		printk(KERN_WARNING
	"Partition configured for %d cpus, "		"Partition configured for %d cpus, "
	"operating system maximum is %d.\n",		"operating system maximum is %u.\n",
	maxcpus, nr_cpu_ids);		maxcpus, nr_cpu_ids);
	maxcpus = nr_cpu_ids;		maxcpus = nr_cpu_ids;
	} else		} else

arch/powerpc/sysdev/xive/native.c

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -511,13 +511,13 @@ static bool xive_parse_provisioning(struct device_node *np)
	static void xive_native_setup_pools(void)		static void xive_native_setup_pools(void)
	{		{
	/* Allocate a pool big enough */		/* Allocate a pool big enough */
	pr_debug("XIVE: Allocating VP block for pool size %d\n", nr_cpu_ids);		pr_debug("XIVE: Allocating VP block for pool size %u\n", nr_cpu_ids);

	xive_pool_vps = xive_native_alloc_vp_block(nr_cpu_ids);		xive_pool_vps = xive_native_alloc_vp_block(nr_cpu_ids);
	if (WARN_ON(xive_pool_vps == XIVE_INVALID_VP))		if (WARN_ON(xive_pool_vps == XIVE_INVALID_VP))
	pr_err("XIVE: Failed to allocate pool VP, KVM might not function\n");		pr_err("XIVE: Failed to allocate pool VP, KVM might not function\n");

	pr_debug("XIVE: Pool VPs allocated at 0x%x for %d max CPUs\n",		pr_debug("XIVE: Pool VPs allocated at 0x%x for %u max CPUs\n",
	xive_pool_vps, nr_cpu_ids);		xive_pool_vps, nr_cpu_ids);
	}		}

arch/tile/kernel/setup.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -1200,7 +1200,7 @@ static void __init validate_hv(void)
	* We use a struct cpumask for this, so it must be big enough.		* We use a struct cpumask for this, so it must be big enough.
	*/		*/
	if ((smp_height * smp_width) > nr_cpu_ids)		if ((smp_height * smp_width) > nr_cpu_ids)
	early_panic("Hypervisor %d x %d grid too big for Linux NR_CPUS %d\n",		early_panic("Hypervisor %d x %d grid too big for Linux NR_CPUS %u\n",
	smp_height, smp_width, nr_cpu_ids);		smp_height, smp_width, nr_cpu_ids);
	#endif		#endif