From: Ralf Baechle <ralf@linux-mips.org>
To: Thomas Petazzoni <thomas.petazzoni@enix.org>
Cc: linux-mips@linux-mips.org, mentre@tcl.ite.mee.com
Subject: Re: Compilation fails with CONFIG_DEBUG_SPINLOCK
Date: Fri, 22 Oct 2004 14:50:19 +0200 [thread overview]
Message-ID: <20041022125019.GA642@linux-mips.org> (raw)
In-Reply-To: <20041013092057.GQ11236@enix.org>
On Wed, Oct 13, 2004 at 11:20:57AM +0200, Thomas Petazzoni wrote:
> I think this is trivial to fix, but I'm not sure what is the right
> place to declare the spin lock and to initialize it.
atomic_lock is intentionally undefined. The code using it should ever
be referenced on uni-processor systems that don't have ll/sc and on those
the spinlock code happens to not reference the spinlock_t argument not
at all. So iow if the compiled code actually references atomic_lock,
something is smelling. In general the reason is not having an
include/asm-mips/mach-<foo>/cpu-feature-overrides.h file. If this is
missing the kernel will fallback to runtime detection of cpu_has_llsc
which due to the performance sensitive nature of most atomic_t users is
a bad idea. So this error is the bomb hidden in the code to alert
users ...
Ralf
prev parent reply other threads:[~2004-10-22 12:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-13 9:20 Compilation fails with CONFIG_DEBUG_SPINLOCK Thomas Petazzoni
2004-10-18 10:03 ` Thomas Petazzoni
2004-10-22 12:50 ` Ralf Baechle [this message]
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