On Sat, 13 Aug 2011, Chris Furlough wrote:
> Greg, please take this at face value, and tell me if you know what the
> problem is here.
>
> * I'm calling fs_create_file to register my node under my parent directory.
> (I get the address from kallsyms, and call it directly).[1]
> * My node shows up in "ls", and I can cat my data from it.[2]
> * My test program uses libusb-0.1.12, and does the following:
> usb_init();
> usb_find_busses();
> usb_find_devices();
>
> * Using strace on my test program, I can see that when usb_find_devices()
> checks the directory my new node is it, it doesn't see it.[3]
> * Digging into usb_find_devices, I see that it's calling readdir() to
> enumerate the items in the directory.[4]
> * According to what strace tells me, readdir is calling getdents().[3]
>
> ANY idea why my node wouldn't show up?
>
>
> Notes:
> 1. I get usbfs_mount, and get the root dentry from it, then walk the linked
> list to find my desired parent directory using this:list_for_each_entry(tmp,&parent->d_subdirs, d_u.d_child).
> 2. ls /proc/bus/usb/005/ -a
> . .. 001 002 003
>
> 3. open("/dev/bus/usb/005",
Here's the problem. Your file node is located under
/proc/bus/usb/005, but the program is looking in /dev/bus/usb/005.
/proc != /dev.
> O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = 3
> getdents(3, /* 4 entries */, 32768) = 64
>
> 4. File linux.c, line 380: while ((entry = readdir(dir)) != NULL) {
Alan Stern
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