usbmon: fix tiny race exposed by the fastboot patches

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
From: Linux Kernel Mailing List
Date: Friday, October 17, 2008 - 5:04 pm

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bb4e3b...
Commit:     bb4e3b5ac81a9601775e62649038934acafa78e2
Parent:     8520f38099ccfdac2147a0852f84ee7a8ee5e197
Author:     Arjan van de Ven <arjan@linux.intel.com>
AuthorDate: Mon Sep 22 15:00:10 2008 -0700
Committer:  Greg Kroah-Hartman <gregkh@suse.de>
CommitDate: Fri Oct 17 14:40:57 2008 -0700

    usbmon: fix tiny race exposed by the fastboot patches
    
    usbmon registers the notifier chain, takes the bus lock and then goes to
    scan the existing devices for hooking up.
    
    Unfortunately, if usb_mon gets initialized while USB bus discovery is
    going on, it's possible that usbmon gets a notifier on one cpu (which runs
    without USB locks), and the scan is going on and also finds the new bus,
    resulting in a double sysfs registration, which then produces a WARNING.
    
    Pete Zaitcev did the bug diagnostics on this one
    
    Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
    Acked-by: Pete Zaitcev <zaitcev@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/usb/mon/mon_main.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
index 442d807..5e0ab42 100644
--- a/drivers/usb/mon/mon_main.c
+++ b/drivers/usb/mon/mon_main.c
@@ -361,12 +361,12 @@ static int __init mon_init(void)
 	}
 	// MOD_INC_USE_COUNT(which_module?);
 
-	usb_register_notify(&mon_nb);
 
 	mutex_lock(&usb_bus_list_lock);
 	list_for_each_entry (ubus, &usb_bus_list, bus_list) {
 		mon_bus_init(ubus);
 	}
+	usb_register_notify(&mon_nb);
 	mutex_unlock(&usb_bus_list_lock);
 	return 0;
 
--
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
usbmon: fix tiny race exposed by the fastboot patches, Linux Kernel Mailing ..., (Fri Oct 17, 5:04 pm)