w1: fixup search to support abort from netlink

Before 63706172f33 "rework kthread_stop()" kthread_should_stop()
always returned false when called from a non-kthread task, after it
would oops as a non-kthread didn't have that structure and netlink was
calling search from a thread which wasn't a kthread.  9d1817cab2f030
"w1: fix oops when w1_search is called from netlink connector",
modified the code to avoid calling kthread_stop from a netlink thread.

Introduce a w1_master flag and bit W1_ABORT_SEARCH to identify abort
to cleanly support both kthread and netlink search abort.  A search
can take seconds to run, so it is important to abort early if the
hardware is removed in the middle of a search.

Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Marcin Jurkowski <marcin1j@gmail.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: Sven Geggus <lists@fuchsschwanzdomain.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 13 insertions, 2 deletions

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 66efa96c4603..67b6d5fb25bc 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -960,8 +960,7 @@ void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb
                         tmp64 = (triplet_ret >> 2);
                         rn |= (tmp64 << i);
 
-                        /* ensure we're called from kthread and not by netlink callback */
-                        if (!dev->priv && kthread_should_stop()) {
+                        if (test_bit(W1_ABORT_SEARCH, &dev->flags)) {
                                 mutex_unlock(&dev->bus_mutex);
                                 dev_dbg(&dev->dev, "Abort w1_search\n");
                                 return;
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index ca8081a101d6..bc329d2bba28 100644
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -155,6 +155,14 @@ struct w1_bus_master
                 u8, w1_slave_found_callback);
 };
 
+/**
+ * enum w1_master_flags - bitfields used in w1_master.flags
+ * @W1_ABORT_SEARCH: abort searching early on shutdown
+ */
+enum w1_master_flags {
+        W1_ABORT_SEARCH = 0,
+};
+
 struct w1_master
 {
         struct list_head        w1_master_entry;
@@ -178,6 +186,8 @@ struct w1_master
         /** 5V strong pullup duration in milliseconds, zero disabled. */
         int                     pullup_duration;
 
+        long                    flags;
+
         struct task_struct      *thread;
         struct mutex            mutex;
         struct mutex            bus_mutex;
diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index 590bd8a7cd1b..423f3c2b9e7d 100644
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -172,6 +172,7 @@ int w1_add_master_device(struct w1_bus_master *master)
 
 #if 0 /* Thread cleanup code, not required currently. */
 err_out_kill_thread:
+        set_bit(W1_ABORT_SEARCH, &dev->flags);
         kthread_stop(dev->thread);
 #endif
 err_out_rm_attr:
@@ -187,6 +188,7 @@ void __w1_remove_master_device(struct w1_master *dev)
         struct w1_netlink_msg msg;
         struct w1_slave *sl, *sln;
 
+        set_bit(W1_ABORT_SEARCH, &dev->flags);
         kthread_stop(dev->thread);
 
         mutex_lock(&w1_mlock);