[PATCH 02/14] w1: fixup search to support abort from netlink

David Fries
2013-12-29T06:53:54Z

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>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Marcin Jurkowski <marcin1j@gmail.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: Sven Geggus <lists@fuchsschwanzdomain.de>
---
drivers/w1/w1.c | 3 +--
drivers/w1/w1.h | 10 ++++++++++
drivers/w1/w1_int.c | 2 ++
3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 66efa96..67b6d5f 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 ca8081a..bc329d2 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 590bd8a..423f3c2 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);
--
1.7.10.4