Sysctl locking?
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2010-10-05 05:03:46
Also in:
lkml
Subsystem:
linux for power macintosh, the rest · Maintainer:
Linus Torvalds
Hi, I tried tracing through sysctl code and it appears that there is no generic locking for reads and writes to a sysctl node and thus a patch like below is needed if proc_handler is a bit more complex than simply storing an integer value. Am I missing something? Thanks. -- Dmitry Input: mac mouse emulation - add locking We need to add appropriate locking when toggling mac mouse emulation on and off to ensure that input device and handler are in consistent state. Signed-off-by: Dmitry Torokhov <redacted> --- drivers/macintosh/mac_hid.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-)
diff --git a/drivers/macintosh/mac_hid.c b/drivers/macintosh/mac_hid.c
index 067f996..6a82388 100644
--- a/drivers/macintosh/mac_hid.c
+++ b/drivers/macintosh/mac_hid.c@@ -23,6 +23,8 @@ static int mouse_button3_keycode = KEY_RIGHTALT; /* right option key */ static struct input_dev *mac_hid_emumouse_dev; +static DEFINE_MUTEX(mac_hid_emumouse_mutex); + static int mac_hid_create_emumouse(void) { static struct lock_class_key mac_hid_emumouse_dev_event_class;
@@ -187,6 +189,10 @@ static int mac_hid_toggle_emumouse(ctl_table *table, int write, int old_val = *valp; int rc; + rc = mutex_lock_killable(&mac_hid_emumouse_mutex); + if (rc) + return rc; + rc = proc_dointvec(table, write, buffer, lenp, ppos); if (rc == 0 && write && *valp != old_val) {
@@ -202,6 +208,8 @@ static int mac_hid_toggle_emumouse(ctl_table *table, int write, if (rc) *valp = old_val; + mutex_unlock(&mac_hid_emumouse_mutex); + return rc; }