Date: Sat, 2 Apr 2005 20:37:04 +0100
From: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: ooyama eiichi <ooyama@tritech.co.jp>, cw@f00f.org,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: kernel stack size
Message-ID: <20050402193704.GU8859@parcelfarce.linux.theplanet.co.uk>
References: <20050402175345.GA28710@taniwha.stupidest.org> <20050403.031542.23015132.ooyama@tritech.co.jp> <20050402182438.GA29095@taniwha.stupidest.org> <20050403.034858.70218818.ooyama@tritech.co.jp> <1112468651.27149.4.camel@localhost.localdomain>
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On Sat, Apr 02, 2005 at 02:04:11PM -0500, Steven Rostedt wrote:
> You can also use globally static variables too. But this makes for
> non-reentry code.
> 
> Sometimes I don't feel that a kmalloc is worth it, and if the function
> in question for the driver would seldom have problems with reentry, I
> use a statically defined global, and protect it with spin_locks. If
> these can also be used in interrupt context, you need to use the
> spin_lock_irqsave variants.  But don't do this if the critical section
> has long latencies.

... and the first time copy_from_user() blocks under your spinlock
you will get a nice shiny deadlock.
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