Re: [PATCH] fs/compat.c: rwsem instead of BKL aroundioctl32_hash_table

[Roland Dreier]

    Andi> It does not make much sense because the ioctl will take the
    Andi> BKL anyways.

True, but it seems pretty ugly to protect the ioctl32 hash with the
BKL.  I think the greater good of reducing use of the BKL should be
looked at.

    Andi> If you wanted to fix it properly better make it use RCU -
    Andi> but it cannot work for the case of calling a compat handler.

I'm not sure I follow what you're saying.  When I looked at this, at
first I thought RCU would be better for the hash lookup, but I didn't
see a way to prevent a compat handler from being removed while it was
running.  That's why I moved to a semaphore, which would hold off the
removal until the handler was done running.  Is this what you mean?
Do you see a way to use RCU here?

Thanks,
  Roland

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