2012-08-14 14:06:44

by Cyrill Gorcunov

Subject: [patch 5/8] fs, epoll: Add procfs fdinfo helper v2

This allow us to print out eventpoll target file descriptor,
events and data, the /proc/pid/fdinfo/fd consists of

| pos: 0
| flags: 02
| tfd: 5 events: 1d data: ffffffffffffffff

This feature is CONFIG_CHECKPOINT_RESTORE only.

v2:
- don't walk over all rb nodes on seq-next,
try to continue from pervious position

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]>
CC: Matthew Helsley <[email protected]>
---
fs/eventpoll.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)

Index: linux-2.6.git/fs/eventpoll.c
===================================================================
--- linux-2.6.git.orig/fs/eventpoll.c
+++ linux-2.6.git/fs/eventpoll.c
@@ -38,6 +38,8 @@
#include <asm/io.h>
#include <asm/mman.h>
#include <linux/atomic.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>

/*
* LOCKING:
@@ -1897,6 +1899,69 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd,
return error;
}

+#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;
+ struct eventpoll *ep = extra->f_file->private_data;
+ struct rb_node *rbp;
+ loff_t num = *pos;
+
+ mutex_lock(&ep->mtx);
+ for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
+ if (num-- == 0)
+ return rbp;
+ }
+
+ return NULL;
+}
+
+static void seq_stop(struct seq_file *m, void *v)
+{
+ struct proc_fdinfo_extra *extra = m->private;
+ struct eventpoll *ep = extra->f_file->private_data;
+ mutex_unlock(&ep->mtx);
+}
+
+static void *seq_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ struct rb_node *rbp = p;
+ ++*pos;
+ return (void *)rb_next(rbp);
+}
+
+static int seq_show(struct seq_file *m, void *v)
+{
+ struct rb_node *rbp = v;
+ struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
+
+ return seq_printf(m, "tfd: %8d events: %8x data: %16llx\n",
+ epi->ffd.fd, epi->event.events,
+ (long long)epi->event.data);
+}
+
+static const struct seq_operations ep_fdinfo_ops = {
+ .start = seq_start,
+ .next = seq_next,
+ .stop = seq_stop,
+ .show = seq_show,
+};
+
+static struct proc_fdinfo_driver ep_fdinfo = {
+ .name = "eventpoll",
+ .ops = &ep_fdinfo_ops,
+ .probe = is_file_epoll,
+};
+
+static int __init ep_register_fdinfo_driver(void)
+{
+ return proc_register_fdinfo_driver(&ep_fdinfo);
+}
+#else
+static void ep_register_fdinfo_driver(void) { }
+#endif /* CONFIG_PROC_FS && CONFIG_CHECKPOINT_RESTORE */
+
static int __init eventpoll_init(void)
{
struct sysinfo si;
@@ -1929,6 +1994,8 @@ static int __init eventpoll_init(void)
pwq_cache = kmem_cache_create("eventpoll_pwq",
sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL);

+ ep_register_fdinfo_driver();
+
return 0;
}
fs_initcall(eventpoll_init);

2012-08-14 14:26:31

by Pavel Emelyanov

Subject: Re: [patch 5/8] fs, epoll: Add procfs fdinfo helper v2

On 08/14/2012 06:03 PM, Cyrill Gorcunov wrote:
> This allow us to print out eventpoll target file descriptor,
> events and data, the /proc/pid/fdinfo/fd consists of
>
> | pos: 0
> | flags: 02
> | tfd: 5 events: 1d data: ffffffffffffffff
>
> This feature is CONFIG_CHECKPOINT_RESTORE only.
>
> v2:
> - don't walk over all rb nodes on seq-next,
> try to continue from pervious position
>
> 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]>
> CC: Matthew Helsley <[email protected]>

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