Input: pmouse - introduce proper locking so state-changing

       operations do not iterfere with each other.
       Also make sure that serio core takes serio->drv_sem
       not only for connect/disconnect but for reconnect
       too.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

2 files changed, 80 insertions, 18 deletions

diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index 0ecf1297b6a8..259e6b70544b 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -68,6 +68,15 @@ __obsolete_setup("psmouse_smartscroll=");
 __obsolete_setup("psmouse_resetafter=");
 __obsolete_setup("psmouse_rate=");
 
+/*
+ * psmouse_sem protects all operations changing state of mouse
+ * (connecting, disconnecting, changing rate or resolution via
+ * sysfs). We could use a per-device semaphore but since there
+ * rarely more than one PS/2 mouse connected and since semaphore
+ * is taken in "slow" paths it is not worth it.
+ */
+static DECLARE_MUTEX(psmouse_sem);
+
 static char *psmouse_protocols[] = { "None", "PS/2", "PS2++", "ThinkPS/2", "GenPS/2", "ImPS/2", "ImExPS/2", "SynPS/2", "AlpsPS/2", "LBPS/2" };
 
 /*
@@ -667,30 +676,40 @@ static void psmouse_cleanup(struct serio *serio)
 
 static void psmouse_disconnect(struct serio *serio)
 {
-        struct psmouse *psmouse, *parent;
+        struct psmouse *psmouse, *parent = NULL;
+
+        psmouse = serio_get_drvdata(serio);
 
         device_remove_file(&serio->dev, &psmouse_attr_rate);
         device_remove_file(&serio->dev, &psmouse_attr_resolution);
         device_remove_file(&serio->dev, &psmouse_attr_resetafter);
 
-        psmouse = serio_get_drvdata(serio);
+        down(&psmouse_sem);
+
         psmouse_set_state(psmouse, PSMOUSE_CMD_MODE);
 
         if (serio->parent && serio->id.type == SERIO_PS_PSTHRU) {
                 parent = serio_get_drvdata(serio->parent);
-                if (parent->pt_deactivate)
-                        parent->pt_deactivate(parent);
+                psmouse_deactivate(parent);
         }
 
         if (psmouse->disconnect)
                 psmouse->disconnect(psmouse);
 
+        if (parent && parent->pt_deactivate)
+                parent->pt_deactivate(parent);
+
         psmouse_set_state(psmouse, PSMOUSE_IGNORE);
 
         input_unregister_device(&psmouse->dev);
         serio_close(serio);
         serio_set_drvdata(serio, NULL);
         kfree(psmouse);
+
+        if (parent)
+                psmouse_activate(parent);
+
+        up(&psmouse_sem);
 }
 
 /*
@@ -702,6 +721,8 @@ static int psmouse_connect(struct serio *serio, struct serio_driver *drv)
         struct psmouse *psmouse, *parent = NULL;
         int retval;
 
+        down(&psmouse_sem);
+
         /*
          * If this is a pass-through port deactivate parent so the device
          * connected to this port can be successfully identified
@@ -711,13 +732,11 @@ static int psmouse_connect(struct serio *serio, struct serio_driver *drv)
                 psmouse_deactivate(parent);
         }
 
-        if (!(psmouse = kmalloc(sizeof(struct psmouse), GFP_KERNEL))) {
+        if (!(psmouse = kcalloc(1, sizeof(struct psmouse), GFP_KERNEL))) {
                 retval = -ENOMEM;
                 goto out;
         }
 
-        memset(psmouse, 0, sizeof(struct psmouse));
-
         ps2_init(&psmouse->ps2dev, serio);
         sprintf(psmouse->phys, "%s/input0", serio->phys);
         psmouse->dev.evbit[0] = BIT(EV_KEY) | BIT(EV_REL);
@@ -785,10 +804,11 @@ static int psmouse_connect(struct serio *serio, struct serio_driver *drv)
         retval = 0;
 
 out:
-        /* If this is a pass-through port the parent awaits to be activated */
+        /* If this is a pass-through port the parent needs to be re-activated */
         if (parent)
                 psmouse_activate(parent);
 
+        up(&psmouse_sem);
         return retval;
 }
 
@@ -805,6 +825,8 @@ static int psmouse_reconnect(struct serio *serio)
                 return -1;
         }
 
+        down(&psmouse_sem);
+
         if (serio->parent && serio->id.type == SERIO_PS_PSTHRU) {
                 parent = serio_get_drvdata(serio->parent);
                 psmouse_deactivate(parent);
@@ -837,6 +859,7 @@ out:
         if (parent)
                 psmouse_activate(parent);
 
+        up(&psmouse_sem);
         return rc;
 }
 
@@ -907,7 +930,16 @@ ssize_t psmouse_attr_set_helper(struct device *dev, const char *buf, size_t coun
 
         if (serio->drv != &psmouse_drv) {
                 retval = -ENODEV;
-                goto out;
+                goto out_unpin;
+        }
+
+        retval = down_interruptible(&psmouse_sem);
+        if (retval)
+                goto out_unpin;
+
+        if (psmouse->state == PSMOUSE_IGNORE) {
+                retval = -ENODEV;
+                goto out_up;
         }
 
         if (serio->parent && serio->id.type == SERIO_PS_PSTHRU) {
@@ -922,7 +954,9 @@ ssize_t psmouse_attr_set_helper(struct device *dev, const char *buf, size_t coun
         if (parent)
                 psmouse_activate(parent);
 
-out:
+ out_up:
+        up(&psmouse_sem);
+ out_unpin:
         serio_unpin_driver(serio);
         return retval;
 }
diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index 2c93ceab831a..b82815a0b65b 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -67,6 +67,37 @@ static void serio_destroy_port(struct serio *serio);
 static void serio_reconnect_port(struct serio *serio);
 static void serio_disconnect_port(struct serio *serio);
 
+static int serio_connect_driver(struct serio *serio, struct serio_driver *drv)
+{
+        int retval;
+
+        down(&serio->drv_sem);
+        retval = drv->connect(serio, drv);
+        up(&serio->drv_sem);
+
+        return retval;
+}
+
+static int serio_reconnect_driver(struct serio *serio)
+{
+        int retval = -1;
+
+        down(&serio->drv_sem);
+        if (serio->drv && serio->drv->reconnect)
+                retval = serio->drv->reconnect(serio);
+        up(&serio->drv_sem);
+
+        return retval;
+}
+
+static void serio_disconnect_driver(struct serio *serio)
+{
+        down(&serio->drv_sem);
+        if (serio->drv)
+                serio->drv->disconnect(serio);
+        up(&serio->drv_sem);
+}
+
 static int serio_match_port(const struct serio_device_id *ids, struct serio *serio)
 {
         while (ids->type || ids->proto) {
@@ -90,7 +121,7 @@ static void serio_bind_driver(struct serio *serio, struct serio_driver *drv)
 
         if (serio_match_port(drv->id_table, serio)) {
                 serio->dev.driver = &drv->driver;
-                if (drv->connect(serio, drv)) {
+                if (serio_connect_driver(serio, drv)) {
                         serio->dev.driver = NULL;
                         goto out;
                 }
@@ -550,7 +581,7 @@ static void serio_destroy_port(struct serio *serio)
 static void serio_reconnect_port(struct serio *serio)
 {
         do {
-                if (!serio->drv || !serio->drv->reconnect || serio->drv->reconnect(serio)) {
+                if (serio_reconnect_driver(serio)) {
                         serio_disconnect_port(serio);
                         serio_find_driver(serio);
                         /* Ok, old children are now gone, we are done */
@@ -679,15 +710,14 @@ static int serio_driver_probe(struct device *dev)
         struct serio *serio = to_serio_port(dev);
         struct serio_driver *drv = to_serio_driver(dev->driver);
 
-        return drv->connect(serio, drv);
+        return serio_connect_driver(serio, drv);
 }
 
 static int serio_driver_remove(struct device *dev)
 {
         struct serio *serio = to_serio_port(dev);
-        struct serio_driver *drv = to_serio_driver(dev->driver);
 
-        drv->disconnect(serio);
+        serio_disconnect_driver(serio);
         return 0;
 }
 
@@ -723,11 +753,9 @@ start_over:
 
 static void serio_set_drv(struct serio *serio, struct serio_driver *drv)
 {
-        down(&serio->drv_sem);
         serio_pause_rx(serio);
         serio->drv = drv;
         serio_continue_rx(serio);
-        up(&serio->drv_sem);
 }
 
 static int serio_bus_match(struct device *dev, struct device_driver *drv)
@@ -787,7 +815,7 @@ static int serio_resume(struct device *dev)
 {
         struct serio *serio = to_serio_port(dev);
 
-        if (!serio->drv || !serio->drv->reconnect || serio->drv->reconnect(serio)) {
+        if (serio_reconnect_driver(serio)) {
                 /*
                  * Driver re-probing can take a while, so better let kseriod
                  * deal with it.