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| author | Alan Stern <stern@rowland.harvard.edu> | 2012-05-14 13:30:03 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-05-14 12:19:56 -0700 |
| commit | 356c05d58af05d582e634b54b40050c73609617b (patch) | |
| tree | 49fd49203678cee0e7650f1b4d55aa3f53527575 /drivers/usb/core/sysfs.c | |
| parent | c836d0ab70acf7b7bd2b698278e8abae9e6d9978 (diff) | |
| download | linux-356c05d58af05d582e634b54b40050c73609617b.tar.gz | |
sysfs: get rid of some lockdep false positives
This patch (as1554) fixes a lockdep false-positive report. The problem arises because lockdep is unable to deal with the tree-structured locks created by the device core and sysfs. This particular problem involves a sysfs attribute method that unregisters itself, not from the device it was called for, but from a descendant device. Lockdep doesn't understand the distinction and reports a possible deadlock, even though the operation is safe. This is the sort of thing that would normally be handled by using a nested lock annotation; unfortunately it's not feasible to do that here. There's no sensible way to tell sysfs when attribute removal occurs in the context of a parent attribute method. As a workaround, the patch adds a new flag to struct attribute telling sysfs not to inform lockdep when it acquires a readlock on a sysfs_dirent instance for the attribute. The readlock is still acquired, but lockdep doesn't know about it and hence does not complain about impossible deadlock scenarios. Also added are macros for static initialization of attribute structures with the ignore_lockdep flag set. The three offending attributes in the USB subsystem are converted to use the new macros. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Tejun Heo <tj@kernel.org> CC: Eric W. Biederman <ebiederm@xmission.com> CC: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/sysfs.c')
| -rw-r--r-- | drivers/usb/core/sysfs.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index 566d9f94f735..9a56e3adf476 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -73,7 +73,7 @@ set_bConfigurationValue(struct device *dev, struct device_attribute *attr, return (value < 0) ? value : count; } -static DEVICE_ATTR(bConfigurationValue, S_IRUGO | S_IWUSR, +static DEVICE_ATTR_IGNORE_LOCKDEP(bConfigurationValue, S_IRUGO | S_IWUSR, show_bConfigurationValue, set_bConfigurationValue); /* String fields */ @@ -595,7 +595,7 @@ static ssize_t usb_dev_authorized_store(struct device *dev, return result < 0? result : size; } -static DEVICE_ATTR(authorized, 0644, +static DEVICE_ATTR_IGNORE_LOCKDEP(authorized, 0644, usb_dev_authorized_show, usb_dev_authorized_store); /* "Safely remove a device" */ @@ -618,7 +618,7 @@ static ssize_t usb_remove_store(struct device *dev, usb_unlock_device(udev); return rc; } -static DEVICE_ATTR(remove, 0200, NULL, usb_remove_store); +static DEVICE_ATTR_IGNORE_LOCKDEP(remove, 0200, NULL, usb_remove_store); static struct attribute *dev_attrs[] = { |