linux-kernel - Re: sys_write() racy for multi-threaded append?

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Message-ID: <20070316172539.1e3e49d5@lxorguk.ukuu.org.uk>
Date:	Fri, 16 Mar 2007 17:25:39 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	"Michael K. Edwards" <medwards.linux@...il.com>
Cc:	"Bodo Eggert" <7eggert@....de>,
	"Eric Dumazet" <dada1@...mosbay.com>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: sys_write() racy for multi-threaded append?

> > gdbstubs is also not terribly SMP aware and for low level work its
> > sometimes easier to have on gdb per processor if you can get your brain
> > around it.
> 
> That's a trick I don't know.  What do you do, fire up the target
> process, put the whole thing to sleep with a SIGSTOP, and then attach
> a separate gdb to each thread after they've been migrated and locked
> down to the destination CPU?

gdbstubs/kgdbstubs is kernel side so you boot the two cores and each core
halts in the debugger on a breakpoint trap. One debug stub uses one
serial port (or one UDP port), the other uses a different one.

Two gdbs and you can stop/play with each processor independently.
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