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fs: Improve eventpoll logging to stop indicting timerfd

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timerfd doesn't create any wakelocks; eventpoll can, and is creating the
wakelocks we see called "[timerfd]".  eventpoll creates two kinds of
wakelocks: a single top-level lock associated with the eventpoll fd
itself, and one additional lock for each fd it is polling that needs such
a lock (e.g. those using EPOLLWAKEUP).  Current code names the per-fd
locks using the undecorated names of the fds' associated files (hence
"[timerfd]"), and is naming the top-level lock after the PID of the caller
and the name of the file behind the first fd for which a per-fd lock is
created.  To make things clearer, the top-level lock is now named using
the caller PID and an "epollfd" designation, while the per-fd locks are
also named with the caller's PID (to associate them with the top-level
lock) and their respective fds' file names.

Port of fix already applied to previous 2 generations.  Note that this
set of changes does not fully solve the problem of eventpoll/timerfd
wakelock attribution to the original process, since most activity is
relayed through system_server, but it does at least ensure that different
eventpoll wakelocks - and their stats - are properly disambiguated.

Test: Ran on device and observed new wakelock naming in
/d/wakeup_sources and (file naming in) lsof output.
Bug: 116363986
Change-Id: I34bada5ddab04cf3830762c745f46bfcd1549cb8
Signed-off-by: John Dias <joaodias@google.com>
Signed-off-by: Kelly Rossmoyer <krossmo@google.com>
Signed-off-by: Miguel de Dios <migueldedios@google.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
This commit is contained in:
John Dias
2016-10-20 10:28:32 -07:00
committed by Pranav Vashi
parent e83da2bf3c
commit 33dbfcc0a1
2 changed files with 21 additions and 3 deletions
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12
fs/eventpoll.c
View File

@@ -1392,15 +1392,23 @@ static int ep_create_wakeup_source(struct epitem *epi)
{
struct name_snapshot n;
struct wakeup_source *ws;
char task_comm_buf[TASK_COMM_LEN];
char buf[64];
get_task_comm(task_comm_buf, current);
if (!epi->ep->ws) {
epi->ep->ws = wakeup_source_register(NULL, "eventpoll");
snprintf(buf, sizeof(buf), "epoll_%.*s_epollfd",
(int)sizeof(task_comm_buf), task_comm_buf);
epi->ep->ws = wakeup_source_register(NULL, buf);
if (!epi->ep->ws)
return -ENOMEM;
}
take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
ws = wakeup_source_register(NULL, n.name);
snprintf(buf, sizeof(buf), "epoll_%.*s_file:%s",
(int)sizeof(task_comm_buf), task_comm_buf, n.name);
ws = wakeup_source_register(NULL, buf);
release_dentry_name_snapshot(&n);
if (!ws)

12
fs/timerfd.c
View File

@@ -45,6 +45,8 @@ struct timerfd_ctx {
bool might_cancel;
};
static atomic_t instance_count = ATOMIC_INIT(0);
static LIST_HEAD(cancel_list);
static DEFINE_SPINLOCK(cancel_lock);
@@ -388,6 +390,9 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
{
int ufd;
struct timerfd_ctx *ctx;
char task_comm_buf[TASK_COMM_LEN];
char file_name_buf[32];
int instance;
/* Check the TFD_* constants for consistency. */
BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
@@ -424,7 +429,12 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
ctx->moffs = ktime_mono_to_real(0);
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
instance = atomic_inc_return(&instance_count);
get_task_comm(task_comm_buf, current);
snprintf(file_name_buf, sizeof(file_name_buf), "[timerfd%d_%.*s]",
instance, (int)sizeof(task_comm_buf), task_comm_buf);
ufd = anon_inode_getfd(file_name_buf, &timerfd_fops, ctx,
O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
if (ufd < 0)
kfree(ctx);