bc8bcc79ea
Impact: fix missing CPUs in /proc/cpuinfo after CPU hotunplug/hotreplug In my test, I found that if a cpu has been offline, the next cpus may not be shown in the /proc/cpuinfo. if one read() cannot consume the whole /proc/cpuinfo, c_start() will be called again in the next read() calls. And *pos has been increased by 1 by the caller(seq_read()). if this time the cpu#*pos is offline, c_start() will return NULL, and the next cpus can not be shown. this fix use next_cpu_nr(*pos - 1, cpu_online_map) to search the next unshown cpu. the most easy way to reproduce this bug: 1) offline cpu#1 (cpu#0 is online) 2) dd ibs=2 if=/proc/cpuinfo the result is that only cpu#0 is shown. cpu#2 and cpu#3 .... cannot be shown in /proc/cpuinfo it's bug. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
185 lines
4.7 KiB
C
185 lines
4.7 KiB
C
#include <linux/smp.h>
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#include <linux/timex.h>
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#include <linux/string.h>
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#include <linux/seq_file.h>
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#include <linux/cpufreq.h>
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/*
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* Get CPU information for use by the procfs.
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*/
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#ifdef CONFIG_X86_32
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static void show_cpuinfo_core(struct seq_file *m, struct cpuinfo_x86 *c,
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unsigned int cpu)
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{
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#ifdef CONFIG_X86_HT
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if (c->x86_max_cores * smp_num_siblings > 1) {
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seq_printf(m, "physical id\t: %d\n", c->phys_proc_id);
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seq_printf(m, "siblings\t: %d\n",
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cpus_weight(per_cpu(cpu_core_map, cpu)));
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seq_printf(m, "core id\t\t: %d\n", c->cpu_core_id);
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seq_printf(m, "cpu cores\t: %d\n", c->booted_cores);
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seq_printf(m, "apicid\t\t: %d\n", c->apicid);
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seq_printf(m, "initial apicid\t: %d\n", c->initial_apicid);
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}
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#endif
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}
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static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
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{
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/*
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* We use exception 16 if we have hardware math and we've either seen
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* it or the CPU claims it is internal
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*/
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int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
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seq_printf(m,
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"fdiv_bug\t: %s\n"
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"hlt_bug\t\t: %s\n"
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"f00f_bug\t: %s\n"
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"coma_bug\t: %s\n"
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"fpu\t\t: %s\n"
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"fpu_exception\t: %s\n"
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"cpuid level\t: %d\n"
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"wp\t\t: %s\n",
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c->fdiv_bug ? "yes" : "no",
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c->hlt_works_ok ? "no" : "yes",
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c->f00f_bug ? "yes" : "no",
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c->coma_bug ? "yes" : "no",
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c->hard_math ? "yes" : "no",
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fpu_exception ? "yes" : "no",
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c->cpuid_level,
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c->wp_works_ok ? "yes" : "no");
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}
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#else
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static void show_cpuinfo_core(struct seq_file *m, struct cpuinfo_x86 *c,
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unsigned int cpu)
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{
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#ifdef CONFIG_SMP
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if (c->x86_max_cores * smp_num_siblings > 1) {
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seq_printf(m, "physical id\t: %d\n", c->phys_proc_id);
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seq_printf(m, "siblings\t: %d\n",
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cpus_weight(per_cpu(cpu_core_map, cpu)));
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seq_printf(m, "core id\t\t: %d\n", c->cpu_core_id);
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seq_printf(m, "cpu cores\t: %d\n", c->booted_cores);
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seq_printf(m, "apicid\t\t: %d\n", c->apicid);
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seq_printf(m, "initial apicid\t: %d\n", c->initial_apicid);
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}
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#endif
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}
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static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
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{
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seq_printf(m,
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"fpu\t\t: yes\n"
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"fpu_exception\t: yes\n"
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"cpuid level\t: %d\n"
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"wp\t\t: yes\n",
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c->cpuid_level);
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}
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#endif
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static int show_cpuinfo(struct seq_file *m, void *v)
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{
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struct cpuinfo_x86 *c = v;
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unsigned int cpu = 0;
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int i;
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#ifdef CONFIG_SMP
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cpu = c->cpu_index;
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#endif
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seq_printf(m, "processor\t: %u\n"
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"vendor_id\t: %s\n"
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"cpu family\t: %d\n"
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"model\t\t: %u\n"
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"model name\t: %s\n",
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cpu,
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c->x86_vendor_id[0] ? c->x86_vendor_id : "unknown",
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c->x86,
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c->x86_model,
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c->x86_model_id[0] ? c->x86_model_id : "unknown");
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if (c->x86_mask || c->cpuid_level >= 0)
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seq_printf(m, "stepping\t: %d\n", c->x86_mask);
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else
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seq_printf(m, "stepping\t: unknown\n");
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if (cpu_has(c, X86_FEATURE_TSC)) {
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unsigned int freq = cpufreq_quick_get(cpu);
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if (!freq)
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freq = cpu_khz;
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seq_printf(m, "cpu MHz\t\t: %u.%03u\n",
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freq / 1000, (freq % 1000));
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}
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/* Cache size */
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if (c->x86_cache_size >= 0)
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seq_printf(m, "cache size\t: %d KB\n", c->x86_cache_size);
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show_cpuinfo_core(m, c, cpu);
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show_cpuinfo_misc(m, c);
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seq_printf(m, "flags\t\t:");
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for (i = 0; i < 32*NCAPINTS; i++)
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if (cpu_has(c, i) && x86_cap_flags[i] != NULL)
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seq_printf(m, " %s", x86_cap_flags[i]);
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seq_printf(m, "\nbogomips\t: %lu.%02lu\n",
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c->loops_per_jiffy/(500000/HZ),
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(c->loops_per_jiffy/(5000/HZ)) % 100);
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#ifdef CONFIG_X86_64
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if (c->x86_tlbsize > 0)
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seq_printf(m, "TLB size\t: %d 4K pages\n", c->x86_tlbsize);
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#endif
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seq_printf(m, "clflush size\t: %u\n", c->x86_clflush_size);
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#ifdef CONFIG_X86_64
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seq_printf(m, "cache_alignment\t: %d\n", c->x86_cache_alignment);
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seq_printf(m, "address sizes\t: %u bits physical, %u bits virtual\n",
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c->x86_phys_bits, c->x86_virt_bits);
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#endif
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seq_printf(m, "power management:");
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for (i = 0; i < 32; i++) {
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if (c->x86_power & (1 << i)) {
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if (i < ARRAY_SIZE(x86_power_flags) &&
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x86_power_flags[i])
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seq_printf(m, "%s%s",
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x86_power_flags[i][0]?" ":"",
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x86_power_flags[i]);
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else
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seq_printf(m, " [%d]", i);
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}
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}
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seq_printf(m, "\n\n");
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return 0;
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}
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static void *c_start(struct seq_file *m, loff_t *pos)
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{
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if (*pos == 0) /* just in case, cpu 0 is not the first */
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*pos = first_cpu(cpu_online_map);
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else
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*pos = next_cpu_nr(*pos - 1, cpu_online_map);
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if ((*pos) < nr_cpu_ids)
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return &cpu_data(*pos);
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return NULL;
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}
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static void *c_next(struct seq_file *m, void *v, loff_t *pos)
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{
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(*pos)++;
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return c_start(m, pos);
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}
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static void c_stop(struct seq_file *m, void *v)
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{
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}
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const struct seq_operations cpuinfo_op = {
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.start = c_start,
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.next = c_next,
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.stop = c_stop,
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.show = show_cpuinfo,
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};
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