[PATCH] Fix overbroad /proc/timer_list file permissions

[PATCH] Fix overbroad /proc/timer_list file permissions

[Joe Korty]

Fix overbroad file permissions on /proc/timer_list.

/proc/timer_list has 0644 permissions, this should be 0444.

Signed-off-by: Joe Korty <joe.korty@ccur.com>

Index: 2.6.28-rc6/kernel/time/timer_list.c
===================================================================
--- 2.6.28-rc6.orig/kernel/time/timer_list.c	2008-11-25 17:32:46.000000000 -0500
+++ 2.6.28-rc6/kernel/time/timer_list.c	2008-11-25 17:33:16.000000000 -0500
@@ -286,7 +286,7 @@
 {
 	struct proc_dir_entry *pe;
 
-	pe = proc_create("timer_list", 0644, NULL, &timer_list_fops);
+	pe = proc_create("timer_list", 0444, NULL, &timer_list_fops);
 	if (!pe)
 		return -ENOMEM;
 	return 0;

[PATCH] Add per-cpu indexing to /proc/timer_list

[Joe Korty]

Per-cpu indexing of /proc/timer_list.

/proc/timer_list, potentially a very large file, is in
danger of overflowing its seq_file buffer.  So 'split up'
the buffering on cpu ID boundaries.  This should make this
file more likely to be useful on largish SMP systems.

The model followed is that in /proc/interrupts, which
splits up its buffering on (most) irq boundaries.

Signed-off-by: Joe Korty <joe.korty@ccur.com>

Index: 2.6.28-rc6/kernel/time/timer_list.c
===================================================================
--- 2.6.28-rc6.orig/kernel/time/timer_list.c	2008-11-25 17:50:43.000000000 -0500
+++ 2.6.28-rc6/kernel/time/timer_list.c	2008-11-25 18:03:44.000000000 -0500
@@ -250,36 +250,70 @@
 static int timer_list_show(struct seq_file *m, void *v)
 {
 	u64 now = ktime_to_ns(ktime_get());
-	int cpu;
+	int i = *(loff_t *)v;
 
-	SEQ_printf(m, "Timer List Version: v0.4\n");
-	SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n", HRTIMER_MAX_CLOCK_BASES);
-	SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);
-
-	for_each_online_cpu(cpu)
-		print_cpu(m, cpu, now);
-
-	SEQ_printf(m, "\n");
-	timer_list_show_tickdevices(m);
+	if (i == 0) {
+		SEQ_printf(m, "Timer List Version: v0.4\n");
+		SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n",
+			HRTIMER_MAX_CLOCK_BASES);
+		SEQ_printf(m, "now at %lld nsecs\n",
+			(unsigned long long)now);
+	}
+
+	if (i < nr_cpu_ids) {
+		if (cpu_online(i))
+			print_cpu(m, i, now);
+	}
+
+	if (i == nr_cpu_ids) {
+		SEQ_printf(m, "\n");
+		timer_list_show_tickdevices(m);
+	}
 
 	return 0;
 }
 
 void sysrq_timer_list_show(void)
 {
-	timer_list_show(NULL, NULL);
+	int i;
+	for (i = 0; i <= nr_cpu_ids; i++) {
+		loff_t v = i;
+		timer_list_show(NULL, &v);
+	}
+}
+
+static void *timer_list_start(struct seq_file *m, loff_t *pos)
+{
+	return (*pos <= nr_cpu_ids) ? pos : NULL;
 }
 
+static void *timer_list_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	(*pos)++;
+	if (*pos > nr_cpu_ids)
+		return NULL;
+	return pos;
+}
+
+static void timer_list_stop(struct seq_file *m, void *v) { }
+
+static const struct seq_operations timer_list_seq_ops = {
+	.start = timer_list_start,
+	.next  = timer_list_next,
+	.stop  = timer_list_stop,
+	.show  = timer_list_show
+};
+
 static int timer_list_open(struct inode *inode, struct file *filp)
 {
-	return single_open(filp, timer_list_show, NULL);
+	return seq_open(filp, &timer_list_seq_ops);
 }
 
 static struct file_operations timer_list_fops = {
 	.open		= timer_list_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= single_release,
+	.release	= seq_release,
 };
 
 static int __init init_timer_list_procfs(void)

Re: [PATCH] Add per-cpu indexing to /proc/timer_list

[Alexey Dobriyan]

On Tue, Nov 25, 2008 at 06:14:45PM -0500, Joe Korty wrote:
> Per-cpu indexing of /proc/timer_list.
> 
> /proc/timer_list, potentially a very large file, is in
> danger of overflowing its seq_file buffer.  So 'split up'
> the buffering on cpu ID boundaries.  This should make this
> file more likely to be useful on largish SMP systems.

What do you mean?

You can't overflow seq_file buffer unless kmalloc() will fail large
allocation. And changing internals doesn't change amount of stuff
to be shown, which is the only thing which can lead to large buffer
need.

> The model followed is that in /proc/interrupts, which
> splits up its buffering on (most) irq boundaries.

Re: [PATCH] Add per-cpu indexing to /proc/timer_list

[Joe Korty]

On Wed, Nov 26, 2008 at 07:50:04AM +0300, Alexey Dobriyan wrote:
> On Tue, Nov 25, 2008 at 06:14:45PM -0500, Joe Korty wrote:
> > Per-cpu indexing of /proc/timer_list.
> > 
> > /proc/timer_list, potentially a very large file, is in
> > danger of overflowing its seq_file buffer.  So 'split up'
> > the buffering on cpu ID boundaries.  This should make this
> > file more likely to be useful on largish SMP systems.
> 
> What do you mean?
> 
> You can't overflow seq_file buffer unless kmalloc() will fail large
> allocation. And changing internals doesn't change amount of stuff
> to be shown, which is the only thing which can lead to large buffer
> need.

You're right, I missed the re-malloc part.

Joe