irq, fs/proc: replace loop with nr_irqs for proc/stat

Replace another nr_irqs loop to avoid the allocation of all sparse
irq entries - use for_each_irq_desc instead.

v2: make sure arch without GENERIC_HARDIRQS works too

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 28 insertions, 14 deletions

diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index aa069acf61a0..c3cbabe8b38e 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -30,6 +30,7 @@
 #include <linux/mm.h>
 #include <linux/mmzone.h>
 #include <linux/pagemap.h>
+#include <linux/irq.h>
 #include <linux/interrupt.h>
 #include <linux/swap.h>
 #include <linux/slab.h>
@@ -501,17 +502,16 @@ static const struct file_operations proc_vmalloc_operations = {
 
 static int show_stat(struct seq_file *p, void *v)
 {
-        int i;
+        int i, j;
         unsigned long jif;
         cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
         cputime64_t guest;
         u64 sum = 0;
         struct timespec boottime;
-        unsigned int *per_irq_sum;
-
-        per_irq_sum = kzalloc(sizeof(unsigned int)*nr_irqs, GFP_KERNEL);
-        if (!per_irq_sum)
-                return -ENOMEM;
+        unsigned int per_irq_sum;
+#ifdef CONFIG_GENERIC_HARDIRQS
+        struct irq_desc *desc;
+#endif
 
         user = nice = system = idle = iowait =
                 irq = softirq = steal = cputime64_zero;
@@ -520,8 +520,6 @@ static int show_stat(struct seq_file *p, void *v)
         jif = boottime.tv_sec;
 
         for_each_possible_cpu(i) {
-                int j;
-
                 user = cputime64_add(user, kstat_cpu(i).cpustat.user);
                 nice = cputime64_add(nice, kstat_cpu(i).cpustat.nice);
                 system = cputime64_add(system, kstat_cpu(i).cpustat.system);
@@ -531,10 +529,12 @@ static int show_stat(struct seq_file *p, void *v)
                 softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
                 steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
                 guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
-                for (j = 0; j < nr_irqs; j++) {
-                        unsigned int temp = kstat_irqs_cpu(j, i);
+                for_each_irq_desc(j, desc)
+                {
+                        unsigned int temp;
+
+                        temp = kstat_irqs_cpu(j, i);
                         sum += temp;
-                        per_irq_sum[j] += temp;
                 }
                 sum += arch_irq_stat_cpu(i);
         }
@@ -577,8 +577,23 @@ static int show_stat(struct seq_file *p, void *v)
         }
         seq_printf(p, "intr %llu", (unsigned long long)sum);
 
-        for (i = 0; i < nr_irqs; i++)
-                seq_printf(p, " %u", per_irq_sum[i]);
+        /* sum again ? it could be updated? */
+        for_each_irq_desc(j, desc)
+        {
+                per_irq_sum = 0;
+                for_each_possible_cpu(i) {
+                        unsigned int temp;
+
+                        temp = kstat_irqs_cpu(j, i);
+                        per_irq_sum += temp;
+                }
+
+#ifdef CONFIG_HAVE_SPARSE_IRQ
+                seq_printf(p, " %u:%u", j, per_irq_sum);
+#else
+                seq_printf(p, " %u", per_irq_sum);
+#endif
+        }
 
         seq_printf(p,
                 "\nctxt %llu\n"
@@ -592,7 +607,6 @@ static int show_stat(struct seq_file *p, void *v)
                 nr_running(),
                 nr_iowait());
 
-        kfree(per_irq_sum);
         return 0;
 }