1 files changed, 124 insertions, 45 deletions

diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index eaa5d3efa79d..c556ed9db13d 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -554,7 +554,7 @@ EXPORT_SYMBOL(handle_sysrq);
 #ifdef CONFIG_INPUT
 
 /* Simple translation table for the SysRq keys */
-static const unsigned char sysrq_xlate[KEY_MAX + 1] =
+static const unsigned char sysrq_xlate[KEY_CNT] =
         "\000\0331234567890-=\177\t"                    /* 0x00 - 0x0f */
         "qwertyuiop[]\r\000as"                          /* 0x10 - 0x1f */
         "dfghjkl;'`\000\\zxcv"                          /* 0x20 - 0x2f */
@@ -563,53 +563,129 @@ static const unsigned char sysrq_xlate[KEY_MAX + 1] =
         "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
         "\r\000/";                                      /* 0x60 - 0x6f */
 
-static bool sysrq_down;
-static int sysrq_alt_use;
-static int sysrq_alt;
-static DEFINE_SPINLOCK(sysrq_event_lock);
+struct sysrq_state {
+        struct input_handle handle;
+        struct work_struct reinject_work;
+        unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
+        unsigned int alt;
+        unsigned int alt_use;
+        bool active;
+        bool need_reinject;
+};
+
+static void sysrq_reinject_alt_sysrq(struct work_struct *work)
+{
+        struct sysrq_state *sysrq =
+                        container_of(work, struct sysrq_state, reinject_work);
+        struct input_handle *handle = &sysrq->handle;
+        unsigned int alt_code = sysrq->alt_use;
+
+        if (sysrq->need_reinject) {
+                /* Simulate press and release of Alt + SysRq */
+                input_inject_event(handle, EV_KEY, alt_code, 1);
+                input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
+                input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
+
+                input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
+                input_inject_event(handle, EV_KEY, alt_code, 0);
+                input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
+        }
+}
 
-static bool sysrq_filter(struct input_handle *handle, unsigned int type,
-                         unsigned int code, int value)
+static bool sysrq_filter(struct input_handle *handle,
+                         unsigned int type, unsigned int code, int value)
 {
+        struct sysrq_state *sysrq = handle->private;
+        bool was_active = sysrq->active;
         bool suppress;
 
-        /* We are called with interrupts disabled, just take the lock */
-        spin_lock(&sysrq_event_lock);
+        switch (type) {
 
-        if (type != EV_KEY)
-                goto out;
+        case EV_SYN:
+                suppress = false;
+                break;
 
-        switch (code) {
+        case EV_KEY:
+                switch (code) {
 
-        case KEY_LEFTALT:
-        case KEY_RIGHTALT:
-                if (value)
-                        sysrq_alt = code;
-                else {
-                        if (sysrq_down && code == sysrq_alt_use)
-                                sysrq_down = false;
+                case KEY_LEFTALT:
+                case KEY_RIGHTALT:
+                        if (!value) {
+                                /* One of ALTs is being released */
+                                if (sysrq->active && code == sysrq->alt_use)
+                                        sysrq->active = false;
 
-                        sysrq_alt = 0;
+                                sysrq->alt = KEY_RESERVED;
+
+                        } else if (value != 2) {
+                                sysrq->alt = code;
+                                sysrq->need_reinject = false;
+                        }
+                        break;
+
+                case KEY_SYSRQ:
+                        if (value == 1 && sysrq->alt != KEY_RESERVED) {
+                                sysrq->active = true;
+                                sysrq->alt_use = sysrq->alt;
+                                /*
+                                 * If nothing else will be pressed we'll need
+                                 * to * re-inject Alt-SysRq keysroke.
+                                 */
+                                sysrq->need_reinject = true;
+                        }
+
+                        /*
+                         * Pretend that sysrq was never pressed at all. This
+                         * is needed to properly handle KGDB which will try
+                         * to release all keys after exiting debugger. If we
+                         * do not clear key bit it KGDB will end up sending
+                         * release events for Alt and SysRq, potentially
+                         * triggering print screen function.
+                         */
+                        if (sysrq->active)
+                                clear_bit(KEY_SYSRQ, handle->dev->key);
+
+                        break;
+
+                default:
+                        if (sysrq->active && value && value != 2) {
+                                sysrq->need_reinject = false;
+                                __handle_sysrq(sysrq_xlate[code], true);
+                        }
+                        break;
                 }
-                break;
 
-        case KEY_SYSRQ:
-                if (value == 1 && sysrq_alt) {
-                        sysrq_down = true;
-                        sysrq_alt_use = sysrq_alt;
+                suppress = sysrq->active;
+
+                if (!sysrq->active) {
+                        /*
+                         * If we are not suppressing key presses keep track of
+                         * keyboard state so we can release keys that have been
+                         * pressed before entering SysRq mode.
+                         */
+                        if (value)
+                                set_bit(code, sysrq->key_down);
+                        else
+                                clear_bit(code, sysrq->key_down);
+
+                        if (was_active)
+                                schedule_work(&sysrq->reinject_work);
+
+                } else if (value == 0 &&
+                           test_and_clear_bit(code, sysrq->key_down)) {
+                        /*
+                         * Pass on release events for keys that was pressed before
+                         * entering SysRq mode.
+                         */
+                        suppress = false;
                 }
                 break;
 
         default:
-                if (sysrq_down && value && value != 2)
-                        __handle_sysrq(sysrq_xlate[code], true);
+                suppress = sysrq->active;
                 break;
         }
 
-out:
-        suppress = sysrq_down;
-        spin_unlock(&sysrq_event_lock);
-
         return suppress;
 }
 
@@ -617,28 +693,28 @@ static int sysrq_connect(struct input_handler *handler,
                          struct input_dev *dev,
                          const struct input_device_id *id)
 {
-        struct input_handle *handle;
+        struct sysrq_state *sysrq;
         int error;
 
-        sysrq_down = false;
-        sysrq_alt = 0;
-
-        handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
-        if (!handle)
+        sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
+        if (!sysrq)
                 return -ENOMEM;
 
-        handle->dev = dev;
-        handle->handler = handler;
-        handle->name = "sysrq";
+        INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
+
+        sysrq->handle.dev = dev;
+        sysrq->handle.handler = handler;
+        sysrq->handle.name = "sysrq";
+        sysrq->handle.private = sysrq;
 
-        error = input_register_handle(handle);
+        error = input_register_handle(&sysrq->handle);
         if (error) {
                 pr_err("Failed to register input sysrq handler, error %d\n",
                         error);
                 goto err_free;
         }
 
-        error = input_open_device(handle);
+        error = input_open_device(&sysrq->handle);
         if (error) {
                 pr_err("Failed to open input device, error %d\n", error);
                 goto err_unregister;
@@ -647,17 +723,20 @@ static int sysrq_connect(struct input_handler *handler,
         return 0;
 
  err_unregister:
-        input_unregister_handle(handle);
+        input_unregister_handle(&sysrq->handle);
  err_free:
-        kfree(handle);
+        kfree(sysrq);
         return error;
 }
 
 static void sysrq_disconnect(struct input_handle *handle)
 {
+        struct sysrq_state *sysrq = handle->private;
+
         input_close_device(handle);
+        cancel_work_sync(&sysrq->reinject_work);
         input_unregister_handle(handle);
-        kfree(handle);
+        kfree(sysrq);
 }
 
 /*