Messages in this thread | | | Date | Sun, 30 Nov 2008 14:25:43 +0100 | From | "Kay Sievers" <> | Subject | Re: [PATCH] fix pktcdvd breakage from commit e105b8bfc769b0545b6f0f395179d1e43cbee822 |
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On Sun, Nov 30, 2008 at 14:21, Al Viro <viro@zeniv.linux.org.uk> wrote: > On Sun, Nov 30, 2008 at 01:41:29PM +0100, Kay Sievers wrote: > >> I posted a fix for that weeks ago. But the pktcdvd maintainer stated, >> that the char device nodes are not used for anything. So the whole use >> of dev_t should be removed entirely. They just blindly claim the same >> char dev_t the block devices use, and conflict with char devices from >> other subsystems. Patching out the /sys/dev/class links fixes the >> oops, but the underlying fundamental breakage will still exist. >> >> Original mail here states: >> "Maybe, but that character device would not be used for anything, >> besides creating sub-directories in /sys/class/pktcdvd. The driver >> implements a block device, not a character device." > > _What_ character device nodes? The only thing that dev_t value used to > be used for was giving contents for a text file - ..../dev in sysfs directory. > With introduction of /sys/dev/char the damn thing got confused for > character device number *by* *device_create()*. That's all. > > There are no character device nodes at all. Driver doesn't claim them. > Not in that call of device_create(), not anywhere else. sysfs doesn't > create them (or any other device nodes). If you mknod such thing as > char device and try to open it, the kernel won't go anywhere near this driver, > whether there'd been other drivers or not. > > So what kind of fundamental breakage are you talking about? All I can see > here is a bogus entry added to bogu^Wmisguided^W /sys/dev/char, which leads > to WARN_ON() in case if somebody had char device with device number numerically > equal to that of our block device and to silent crapping into /sys/dev/char > if no such char device had been there already
Pktcdvd creates char _and_ block device nodes at the same time, while the char nodes are not allocated, but created and conflict in /sys/dev/ with properly allocated ones from other subsystems. Your patch just papers over this bug.
Kay
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