Messages in this thread |  | | Date | Tue, 30 Oct 2001 21:33:09 -0500 (EST) | From | Alexander Viro <> | Subject | Re: rmmod whilst reading/writing sysctl |
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On Wed, 31 Oct 2001, John Levon wrote:
> > Where is the prevention of module unload whilst a sysctl from a module is being read/written ? > > sysctl syscall is protected by BKL, but I can't see similar code for the cat >/proc/sys/...
... and that protection is worth nothing, since we copy data to/from userland. Forget about BKL - it doesn't prevent races.
There is a shitload of rmmod (and plain "we remove the object" - it doesn't have to be a module) races in that area. Composite trees _suck_. sysctls, devfs, ddfs - whatever. If tree is served by several drivers - it's broken.
In case of sysctls I have an old patch that could be turned into something working, but that will take a lot of changes in code that exports sysctls, so that may be very painful.
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