Messages in this thread | | | Date | Fri, 21 Dec 2007 20:22:23 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 4/4] usb: libusual: locking cleanup |
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On Fri, 21 Dec 2007 00:00:04 -0800 Daniel Walker <dwalker@mvista.com> wrote:
> I converted the usu_init_notify semaphore to normal mutex usage, and it > should still prevent the request_module before the init routine is > complete. Before it acted more like a complete, now the mutex protects > two distinct section from running at the same time.. > > Signed-off-by: Daniel Walker <dwalker@mvista.com> > > --- > drivers/usb/storage/libusual.c | 14 ++++++-------- > 1 file changed, 6 insertions(+), 8 deletions(-) > > Index: linux-2.6.23/drivers/usb/storage/libusual.c > =================================================================== > --- linux-2.6.23.orig/drivers/usb/storage/libusual.c > +++ linux-2.6.23/drivers/usb/storage/libusual.c > @@ -9,6 +9,7 @@ > #include <linux/usb_usual.h> > #include <linux/vmalloc.h> > #include <linux/kthread.h> > +#include <linux/mutex.h> > > /* > */ > @@ -30,7 +31,7 @@ static atomic_t usu_bias = ATOMIC_INIT(U > #define BIAS_NAME_SIZE (sizeof("usb-storage")) > static const char *bias_names[3] = { "none", "usb-storage", "ub" }; > > -static struct semaphore usu_init_notify; > +static DEFINE_MUTEX(usu_probe_mutex); > static DECLARE_COMPLETION(usu_end_notify); > static atomic_t total_threads = ATOMIC_INIT(0); > > @@ -178,10 +179,7 @@ static int usu_probe_thread(void *arg) > int rc; > unsigned long flags; > > - /* A completion does not work here because it's counted. */ > - down(&usu_init_notify); > - up(&usu_init_notify); > - > + mutex_lock(&usu_probe_mutex); > rc = request_module(bias_names[type]); > spin_lock_irqsave(&usu_lock, flags); > if (rc == 0 && (st->fls & USU_MOD_FL_PRESENT) == 0) { > @@ -194,6 +192,7 @@ static int usu_probe_thread(void *arg) > } > st->fls &= ~USU_MOD_FL_THREAD; > spin_unlock_irqrestore(&usu_lock, flags); > + mutex_unlock(&usu_probe_mutex); > > complete_and_exit(&usu_end_notify, 0); > } > @@ -204,10 +203,9 @@ static int __init usb_usual_init(void) > { > int rc; > > - sema_init(&usu_init_notify, 0); > - > + mutex_lock(&usu_probe_mutex); > rc = usb_register(&usu_driver); > - up(&usu_init_notify); > + mutex_unlock(&usu_probe_mutex); > return rc; > }
That's some pretty hairy-looking code you're playing with there. Has this been runtime tested?
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