From: Manish Varma <varmam@xxxxxxxxxx> 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 "epollN:P" (instead of just "eventpoll"), where N is a unique ID token, and P is the PID of the creating process. 2) individual per-underlying-file descriptor 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. Co-developed-by: Kelly Rossmoyer <krossmo@xxxxxxxxxx> Signed-off-by: Kelly Rossmoyer <krossmo@xxxxxxxxxx> Signed-off-by: Manish Varma <varmam@xxxxxxxxxx> Co-developed-by: Isaac J. Manjarres <isaacmanjarres@xxxxxxxxxx> Signed-off-by: Isaac J. Manjarres <isaacmanjarres@xxxxxxxxxx> --- drivers/base/power/wakeup.c | 12 +++++++++--- fs/eventpoll.c | 11 +++++++++-- include/linux/pm_wakeup.h | 8 ++++---- 3 files changed, 22 insertions(+), 9 deletions(-) v1 -> v2: - Renamed instance count to wakesource_create_id to better describe its purpose. - Changed the wakeup source naming convention for wakeup sources created by eventpoll to avoid changing the timerfd names. - Used the PID of the process instead of the process name for the sake of uniqueness when creating wakeup sources. v2 -> v3: - Changed wakeup_source_register() to take in a format string and arguments to avoid duplicating code to construct wakeup source names. - Moved the definition of wakesource_create_id so that it is always defined to fix an compilation error. v3 -> v4: - Changed the naming convention for the top-level epoll wakeup sources to include an ID for uniqueness. This is needed in cases where a process is using two epoll fds. - Edited commit log to reflect new changes and add new tags. v4 -> v5: - Added the format attribute to the wakeup_source_register() function to address a warning from the kernel test robot: https://lore.kernel.org/all/202406050504.UvdlPAQ0-lkp@xxxxxxxxx/ diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c index 752b417e8129..04a808607b62 100644 --- a/drivers/base/power/wakeup.c +++ b/drivers/base/power/wakeup.c @@ -209,13 +209,19 @@ EXPORT_SYMBOL_GPL(wakeup_source_remove); /** * wakeup_source_register - Create wakeup source and add it to the list. * @dev: Device this wakeup source is associated with (or NULL if virtual). - * @name: Name of the wakeup source to register. + * @fmt: format string for the wakeup source name */ -struct wakeup_source *wakeup_source_register(struct device *dev, - const char *name) +__printf(2, 3) struct wakeup_source *wakeup_source_register(struct device *dev, + const char *fmt, ...) { struct wakeup_source *ws; int ret; + char name[128]; + va_list args; + + va_start(args, fmt); + vsnprintf(name, sizeof(name), fmt, args); + va_end(args); ws = wakeup_source_create(name); if (ws) { diff --git a/fs/eventpoll.c b/fs/eventpoll.c index f53ca4f7fced..941df15208a4 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -338,6 +338,7 @@ static void __init epoll_sysctls_init(void) #define epoll_sysctls_init() do { } while (0) #endif /* CONFIG_SYSCTL */ +static atomic_t wakesource_create_id = ATOMIC_INIT(0); static const struct file_operations eventpoll_fops; static inline int is_file_epoll(struct file *f) @@ -1545,15 +1546,21 @@ static int ep_create_wakeup_source(struct epitem *epi) { struct name_snapshot n; struct wakeup_source *ws; + pid_t task_pid; + int id; + + task_pid = task_pid_nr(current); if (!epi->ep->ws) { - epi->ep->ws = wakeup_source_register(NULL, "eventpoll"); + id = atomic_inc_return(&wakesource_create_id); + epi->ep->ws = wakeup_source_register(NULL, "epoll:%d:%d", id, task_pid); 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); + ws = wakeup_source_register(NULL, "epollitem%d:%d.%s", id, task_pid, n.name.name); release_dentry_name_snapshot(&n); if (!ws) diff --git a/include/linux/pm_wakeup.h b/include/linux/pm_wakeup.h index 76cd1f9f1365..1fb6dca981c2 100644 --- a/include/linux/pm_wakeup.h +++ b/include/linux/pm_wakeup.h @@ -99,8 +99,8 @@ extern struct wakeup_source *wakeup_source_create(const char *name); extern void wakeup_source_destroy(struct wakeup_source *ws); extern void wakeup_source_add(struct wakeup_source *ws); extern void wakeup_source_remove(struct wakeup_source *ws); -extern struct wakeup_source *wakeup_source_register(struct device *dev, - const char *name); +extern __printf(2, 3) struct wakeup_source *wakeup_source_register(struct device *dev, + const char *fmt, ...); extern void wakeup_source_unregister(struct wakeup_source *ws); extern int wakeup_sources_read_lock(void); extern void wakeup_sources_read_unlock(int idx); @@ -140,8 +140,8 @@ static inline void wakeup_source_add(struct wakeup_source *ws) {} static inline void wakeup_source_remove(struct wakeup_source *ws) {} -static inline struct wakeup_source *wakeup_source_register(struct device *dev, - const char *name) +static inline __printf(2, 3) struct wakeup_source *wakeup_source_register(struct device *dev, + const char *fmt, ...) { return NULL; } -- 2.45.2.505.gda0bf45e8d-goog
