2012-08-14 14:06:43

by Cyrill Gorcunov

Subject: [patch 4/8] fs, eventfd: Add procfs fdinfo helper

This allow us to print out raw counter value.
The /proc/pid/fdinfo/fd output is

| pos: 0
| flags: 04002
| eventfd-count: 5a

This feature is CONFIG_CHECKPOINT_RESTORE only.

Signed-off-by: Cyrill Gorcunov <[email protected]>
CC: Al Viro <[email protected]>
CC: Alexey Dobriyan <[email protected]>
CC: Andrew Morton <[email protected]>
CC: Pavel Emelyanov <[email protected]>
CC: James Bottomley <[email protected]>
---
fs/eventfd.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)

Index: linux-2.6.git/fs/eventfd.c
===================================================================
--- linux-2.6.git.orig/fs/eventfd.c
+++ linux-2.6.git/fs/eventfd.c
@@ -19,6 +19,8 @@
#include <linux/export.h>
#include <linux/kref.h>
#include <linux/eventfd.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>

struct eventfd_ctx {
struct kref kref;
@@ -433,3 +435,56 @@ SYSCALL_DEFINE1(eventfd, unsigned int, c
return sys_eventfd2(count, 0);
}

+#if defined(CONFIG_PROC_FS) && defined(CONFIG_CHECKPOINT_RESTORE)
+
+static void *seq_start(struct seq_file *m, loff_t *pos)
+{
+ struct proc_fdinfo_extra *extra = m->private;
+ return *pos == 0 ? extra->f_file : NULL;
+}
+
+static void *seq_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ ++*pos;
+ return NULL;
+}
+
+static int seq_show(struct seq_file *m, void *v)
+{
+ struct eventfd_ctx *ctx = ((struct file *)v)->private_data;
+
+ spin_lock_irq(&ctx->wqh.lock);
+ seq_printf(m, "eventfd-count: %16llx\n",
+ (unsigned long long)ctx->count);
+ spin_unlock_irq(&ctx->wqh.lock);
+
+ return 0;
+}
+
+static void seq_stop(struct seq_file *p, void *v) { }
+
+static const struct seq_operations eventfd_fdinfo_ops = {
+ .start = seq_start,
+ .next = seq_next,
+ .stop = seq_stop,
+ .show = seq_show,
+};
+
+static int is_eventfd_file(struct file *file)
+{
+ return file->f_op == &eventfd_fops;
+}
+
+static struct proc_fdinfo_driver eventfd_fdinfo = {
+ .name = "eventfd",
+ .ops = &eventfd_fdinfo_ops,
+ .probe = is_eventfd_file,
+};
+
+static int __init eventfd_init(void)
+{
+ return proc_register_fdinfo_driver(&eventfd_fdinfo);
+}
+fs_initcall(eventfd_init);
+
+#endif /* CONFIG_PROC_FS && CONFIG_CHECKPOINT_RESTORE */

2012-08-14 14:22:45

by Pavel Emelyanov

Subject: Re: [patch 4/8] fs, eventfd: Add procfs fdinfo helper

On 08/14/2012 06:03 PM, Cyrill Gorcunov wrote:
> This allow us to print out raw counter value.
> The /proc/pid/fdinfo/fd output is
>
> | pos: 0
> | flags: 04002
> | eventfd-count: 5a
>
> This feature is CONFIG_CHECKPOINT_RESTORE only.
>
> Signed-off-by: Cyrill Gorcunov <[email protected]>
> CC: Al Viro <[email protected]>
> CC: Alexey Dobriyan <[email protected]>
> CC: Andrew Morton <[email protected]>
> CC: Pavel Emelyanov <[email protected]>
> CC: James Bottomley <[email protected]>

Acked-by: Pavel Emelyanov <[email protected]>