From 33dea0e730e03814f0cd71c604185ba1c7fad51d Mon Sep 17 00:00:00 2001
From: Jason Wessel <jason.wessel@windriver.com>
Date: Tue, 5 Oct 2010 14:38:36 -0500
Subject: [PATCH 3/3] sysrq,keyboard: properly deal with alt-sysrq in sysrq input filter
This patch addresses 2 problems:
1) You should still be able to use alt-PrintScreen to capture a grab
of a single window when the sysrq filter is active.
2) The sysrq filter should reset the low level key mask so that future
key presses will not show up as a repeated key. The problem was
that when you executed alt-sysrq g and then resumed the kernel, you
would have to press 'g' twice to get it working again.
CC: Dmitry Torokhov <dmitry.torokhov@gmail.com>
CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: linux-input@vger.kernel.org
Reported-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
drivers/char/sysrq.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 61 insertions(+), 3 deletions(-)
@@ -566,6 +566,57 @@ static const unsigned char sysrq_xlate[KEY_MAX + 1] =
static bool sysrq_down;
static int sysrq_alt_use;
static int sysrq_alt;
+static bool sysrq_kbd_triggered;
+
+/*
+ * This function was a copy of input_pass_event but modified to allow
+ * by-passing a specific filter, to allow for injected events without
+ * filter recursion.
+ */
+static void input_pass_event_ignore(struct input_dev *dev,
+ unsigned int type, unsigned int code, int value,
+ struct input_handle *ignore_handle)
+{
+ struct input_handler *handler;
+ struct input_handle *handle;
+
+ rcu_read_lock();
+
+ handle = rcu_dereference(dev->grab);
+ if (handle)
+ handle->handler->event(handle, type, code, value);
+ else {
+ bool filtered = false;
+
+ list_for_each_entry_rcu(handle, &dev->h_list, d_node) {
+ if (!handle->open || handle == ignore_handle)
+ continue;
+ handler = handle->handler;
+ if (!handler->filter) {
+ if (filtered)
+ break;
+
+ handler->event(handle, type, code, value);
+
+ } else if (handler->filter(handle, type, code, value))
+ filtered = true;
+ }
+ }
+
+ rcu_read_unlock();
+}
+
+/*
+ * Pass along alt-print_screen, if there was no sysrq processing by
+ * sending a key press down and then passing the key up event.
+ */
+static void simulate_alt_sysrq(struct input_handle *handle)
+{
+ input_pass_event_ignore(handle->dev, EV_KEY, KEY_SYSRQ, 1, handle);
+ input_pass_event_ignore(handle->dev, EV_SYN, SYN_REPORT, 0, handle);
+ input_pass_event_ignore(handle->dev, EV_KEY, KEY_SYSRQ, 0, handle);
+ input_pass_event_ignore(handle->dev, EV_SYN, SYN_REPORT, 0, handle);
+}
static bool sysrq_filter(struct input_handle *handle, unsigned int type,
unsigned int code, int value)
@@ -580,9 +631,11 @@ static bool sysrq_filter(struct input_handle *handle, unsigned int type,
if (value)
sysrq_alt = code;
else {
- if (sysrq_down && code == sysrq_alt_use)
+ if (sysrq_down && code == sysrq_alt_use) {
sysrq_down = false;
-
+ if (!sysrq_kbd_triggered)
+ simulate_alt_sysrq(handle);
+ }
sysrq_alt = 0;
}
break;
@@ -590,13 +643,18 @@ static bool sysrq_filter(struct input_handle *handle, unsigned int type,
case KEY_SYSRQ:
if (value == 1 && sysrq_alt) {
sysrq_down = true;
+ sysrq_kbd_triggered = false;
sysrq_alt_use = sysrq_alt;
}
break;
default:
- if (sysrq_down && value && value != 2)
+ if (sysrq_down && value && value != 2 && !sysrq_kbd_triggered) {
+ sysrq_kbd_triggered = true;
__handle_sysrq(sysrq_xlate[code], true);
+ /* Clear any handled keys from being flagged as a repeated stroke */
+ __clear_bit(code, handle->dev->key);
+ }
break;
}
--
1.6.3.3