On Thu, 19 Apr 2007 01:58:54 -0600
"Eric W. Biederman" <[email protected]> wrote:
> From: Eric W. Biederman <[email protected]>
>
> This patch starts krfcommd using kthread_run instead of a combination
> of kernel_thread and daemonize making the code slightly simpler
> and more maintainable.
gargh, the more I look at these things, the more I agree with Christoph.
> Cc: Marcel Holtmann <[email protected]>
> Signed-off-by: Eric W. Biederman <[email protected]>
> ---
> net/bluetooth/rfcomm/core.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
> index 34f993a..baaad49 100644
> --- a/net/bluetooth/rfcomm/core.c
> +++ b/net/bluetooth/rfcomm/core.c
> @@ -38,6 +38,7 @@
> #include <linux/net.h>
> #include <linux/mutex.h>
> #include <linux/freezer.h>
> +#include <linux/kthread.h>
>
> #include <net/sock.h>
> #include <asm/uaccess.h>
> @@ -1938,7 +1939,6 @@ static int rfcomm_run(void *unused)
>
> atomic_inc(&running);
>
> - daemonize("krfcommd");
> set_user_nice(current, -10);
>
> BT_DBG("");
> @@ -2058,7 +2058,7 @@ static int __init rfcomm_init(void)
>
> hci_register_cb(&rfcomm_cb);
>
> - kernel_thread(rfcomm_run, NULL, CLONE_KERNEL);
> + kthread_run(rfcomm_run, NULL, "krfcommd");
>
> if (class_create_file(bt_class, &class_attr_rfcomm_dlc) < 0)
> BT_ERR("Failed to create RFCOMM info file");
We should remove the file-wide `terminate' and `running' and switch the
thread management over to kthread_run(), kthread_stop() and
kthread_should_stop().
btw, this:
static void rfcomm_worker(void)
{
BT_DBG("");
while (!atomic_read(&terminate)) {
try_to_freeze();
if (!test_bit(RFCOMM_SCHED_WAKEUP, &rfcomm_event)) {
/* No pending events. Let's sleep.
* Incoming connections and data will wake us up. */
set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
/* Process stuff */
clear_bit(RFCOMM_SCHED_WAKEUP, &rfcomm_event);
rfcomm_process_sessions();
}
set_current_state(TASK_RUNNING);
return;
}
appears to have the classic sleep/wakeup bug: if the wakeup happens after
we tested RFCOMM_SCHED_WAKEUP we will miss it.
Easy fix:
From: Andrew Morton <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
net/bluetooth/rfcomm/core.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff -puN net/bluetooth/rfcomm/core.c~rfcomm_worker-fix-wakeup-race net/bluetooth/rfcomm/core.c
--- a/net/bluetooth/rfcomm/core.c~rfcomm_worker-fix-wakeup-race
+++ a/net/bluetooth/rfcomm/core.c
@@ -1855,18 +1855,18 @@ static void rfcomm_worker(void)
while (!atomic_read(&terminate)) {
try_to_freeze();
+ set_current_state(TASK_INTERRUPTIBLE);
if (!test_bit(RFCOMM_SCHED_WAKEUP, &rfcomm_event)) {
/* No pending events. Let's sleep.
* Incoming connections and data will wake us up. */
- set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
+ set_current_state(TASK_RUNNING);
/* Process stuff */
clear_bit(RFCOMM_SCHED_WAKEUP, &rfcomm_event);
rfcomm_process_sessions();
}
- set_current_state(TASK_RUNNING);
return;
}
_
(I think it's safer and saner to always run rfcomm_process_sessions() while
in state TASK_RUNNING, not maybe-in-state-TASK_INTERRUPTIBLE)
-
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