On Sep 16, 2005, at 12:02:59, linux-os (Dick Johnson) wrote:
Somebody reported to me that there was some special "optimization"
in Linux that interpreted ioctl() function calls without regard to
the specific device that was open (gawd I hope not), and that if
you used "already-used" function numbers for your device-specific
ioctl(), then strange things would occur.
IIRC, that used to be the case, but isn't anymore.
However, the kernel is now LOCKED during an ioctl() call. Older
Linux versions didn't lock the kernel. The upshotof this is that if
you have some ioctl() function that takes some time, like testing
the memory in your board, you will find the system unresponsive
during that test! You can unlock the kernel in your ioctl() if this
is a problem.
This is *completely* wrong. The kernel used to lock_kernel() for
*every* ioctl. Recent changes added locked and unlocked ioctls, such
that ioctls that do not need the BKL can ignore it completely. You
claimed to have read the code, given this typical Wrongbot statement,
I guess I can say for sure that you didn't.
Cheers,
Kyle Moffett
--
Premature optimization is the root of all evil in programming
-- C.A.R. Hoare
PS: Use a different email service! Your "I tried to kill it with
the above dot" and bullshit apology is worth zilch. A quick
calculation shows that over the last month and a half, you have
sent 76 or so emails to the list, all of which have contained your
useless 663-byte corporate message, meaning you have sent 50K of spam
to the list over that time period, which has been distributed to
several thousand accounts by vger, resulting in probably over 100MB
of spam over that time period. Fix it or use a different email account!
I am not the intended recipient for the following email text. I will
destroy all copies of this information, including further copies of
it, because I am not the intended recipient of those either. Plonk!
.
I apologize for the following. I tried to kill it with the above dot :
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