w1: hold bus_mutex in netlink and search

The bus_mutex needs to be taken to serialize access to a specific bus.
netlink wasn't updated when bus_mutex was added and was calling
without that lock held, and not all of the masters were holding the
bus_mutex in a search.  This was causing the ds2490 hardware to stop
responding when both netlink and /sys slaves were executing bus
commands at the same time.

Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/w1/w1_netlink.c b/drivers/w1/w1_netlink.c
index a5dc21934cf2..5234964fe001 100644
--- a/drivers/w1/w1_netlink.c
+++ b/drivers/w1/w1_netlink.c
@@ -246,11 +246,16 @@ static int w1_process_command_master(struct w1_master *dev,
 {
         int err = -EINVAL;
 
+        /* drop bus_mutex for search (does it's own locking), and add/remove
+         * which doesn't use the bus
+         */
         switch (req_cmd->cmd) {
         case W1_CMD_SEARCH:
         case W1_CMD_ALARM_SEARCH:
         case W1_CMD_LIST_SLAVES:
+                mutex_unlock(&dev->bus_mutex);
                 err = w1_get_slaves(dev, req_msg, req_hdr, req_cmd);
+                mutex_lock(&dev->bus_mutex);
                 break;
         case W1_CMD_READ:
         case W1_CMD_WRITE:
@@ -262,8 +267,12 @@ static int w1_process_command_master(struct w1_master *dev,
                 break;
         case W1_CMD_SLAVE_ADD:
         case W1_CMD_SLAVE_REMOVE:
+                mutex_unlock(&dev->bus_mutex);
+                mutex_lock(&dev->mutex);
                 err = w1_process_command_addremove(dev, req_msg, req_hdr,
                         req_cmd);
+                mutex_unlock(&dev->mutex);
+                mutex_lock(&dev->bus_mutex);
                 break;
         default:
                 err = -EINVAL;
@@ -400,7 +409,7 @@ static void w1_process_cb(struct w1_master *dev, struct w1_async_cmd *async_cmd)
         struct w1_slave *sl = node->sl;
         struct w1_netlink_cmd *cmd = NULL;
 
-        mutex_lock(&dev->mutex);
+        mutex_lock(&dev->bus_mutex);
         dev->portid = node->block->portid;
         if (sl && w1_reset_select_slave(sl))
                 err = -ENODEV;
@@ -437,7 +446,7 @@ static void w1_process_cb(struct w1_master *dev, struct w1_async_cmd *async_cmd)
         else
                 atomic_dec(&dev->refcnt);
         dev->portid = 0;
-        mutex_unlock(&dev->mutex);
+        mutex_unlock(&dev->bus_mutex);
 
         mutex_lock(&dev->list_mutex);
         list_del(&async_cmd->async_entry);