timerfd doesn't create any wakelocks, but eventpoll can. When it does,
it names them after the underlying file descriptor, and since all
timerfd file descriptors are named "[timerfd]" (which saves memory on
systems like desktops with potentially many timerfd instances), all
wakesources created as a result of using the eventpoll-on-timerfd idiom
are called... "[timerfd]".
However, it becomes impossible to tell which "[timerfd]" wakesource is
affliated with which process and hence troubleshooting is difficult.
This change addresses this problem by changing the way eventpoll
wakesources are named:
1) the top-level per-process eventpoll wakesource is now named "epoll:P"
(instead of just "eventpoll"), where P, is the PID of the creating
process.
2) individual per-underlying-filedescriptor eventpoll wakesources are
now named "epollitemN:P.F", where N is a unique ID token and P is PID
of the creating process and F is the name of the underlying file
descriptor.
All together that should be splitted up into a change to eventpoll and
timerfd (or other file descriptors).
Co-developed-by: Kelly Rossmoyer <krossmo@xxxxxxxxxx>
Signed-off-by: Kelly Rossmoyer <krossmo@xxxxxxxxxx>
Signed-off-by: Manish Varma <varmam@xxxxxxxxxx>
---
fs/eventpoll.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 7df8c0fa462b..8d3369a02633 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -297,6 +297,7 @@ static LIST_HEAD(tfile_check_list);
static long long_zero;
static long long_max = LONG_MAX;
+static atomic_t wakesource_create_id = ATOMIC_INIT(0);
struct ctl_table epoll_table[] = {
{
@@ -1451,15 +1452,23 @@ static int ep_create_wakeup_source(struct epitem *epi)
{
struct name_snapshot n;
struct wakeup_source *ws;
+ pid_t task_pid;
+ char buf[64];
+ int id;
+
+ task_pid = task_pid_nr(current);
if (!epi->ep->ws) {
- epi->ep->ws = wakeup_source_register(NULL, "eventpoll");
+ snprintf(buf, sizeof(buf), "epoll:%d", task_pid);
+ epi->ep->ws = wakeup_source_register(NULL, buf);
if (!epi->ep->ws)
return -ENOMEM;
}
+ id = atomic_inc_return(&wakesource_create_id);
take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
- ws = wakeup_source_register(NULL, n.name.name);
+ snprintf(buf, sizeof(buf), "epollitem%d:%d.%s", id, task_pid, n.name.name);
+ ws = wakeup_source_register(NULL, buf);
release_dentry_name_snapshot(&n);
if (!ws)
--
2.31.0.291.g576ba9dcdaf-goog
