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>

1 files changed, 44 insertions, 10 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;
 }