Re: [NBD] Use per-device semaphore instead of BKL

From: Herbert Xu
Date: Sun Nov 20 2005 - 15:43:19 EST

On Sun, Nov 20, 2005 at 12:19:17PM -0500, Paul Clements wrote:
> The dropping of the lock in nbd_do_it is actually critical to the way
> nbd functions. nbd_do_it runs for the lifetime of the nbd device, so if
> nbd_do_it were holding some lock (BKL or otherwise), we'd have big problems.

Why would you want to issue an ioctl from a different process while
nbd-client is still running?

Allow ioctl's while nbd_do_it is in progress is a *serious* bug. For a
start, if someone else clears the socket then nbd_read_stat will crash.

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