Hi,
matthieu castet wrote:
Then they should be fixed. Any specific examples?
I am a little lasy to list all, but some drivers in driver/usb should
have this problem : the first driver I look : ./misc/phidgetkit.c do
[1]. So sysfs read don't check if to_usb_interface or usb_get_intfdata
return NULL pointer...
And it is a bit your fault, as many developper should have read your
great tutorial [2] ;)
Also I always see driver free their privatre data in device disconnect,
so if read/write from sysfs aren't serialized with device disconnect
there are still a possible race like I show in my example.
Yes, you are correct. Again, any specific drivers you see with this
problem?
I believe near all drivers that use sysfs via device_create_file, as I
never see them use mutex in read/write in order to check there aren't in
the same time in their disconnect that could free there private data
when they do operation on it...
Couldn't be possible the make device_remove_file blocking until all the
open file are closed ?
thanks,
Matthieu
[1]
#define show_input(value) \
static ssize_t show_input##value(struct device *dev, char *buf) \
{ \
struct usb_interface *intf = to_usb_interface(dev); \
struct phidget_interfacekit *kit = usb_get_intfdata(intf); \
\
return sprintf(buf, "%d\n", kit->inputs[value - 1]); \
} \
static DEVICE_ATTR(input##value, S_IRUGO, show_input##value, NULL);
[2] http://www.linuxjournal.com/article/7353
So will there be a fix in the kernel, or all this driver are broken and
should be fixed ?
thanks
Matthieu
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