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From: Zachary Amsden <zach@vmware.com>
To: Chris Wright <chrisw@osdl.org>
Cc: akpm@osdl.org, chrisl@vmware.com, hpa@zytor.com,
	linux-kernel@vger.kernel.org, mbligh@mbligh.org,
	pratap@vmware.com, virtualization@lists.osdl.org,
	zwane@arm.linux.org.uk
Subject: Re: [PATCH 2/6] i386 virtualization - Remove some dead debugging code
Date: Mon, 15 Aug 2005 22:08:37 -0700	[thread overview]
Message-ID: <430174D5.20209@vmware.com> (raw)
In-Reply-To: <20050816043843.GT7762@shell0.pdx.osdl.net>

Chris Wright wrote:

>* zach@vmware.com (zach@vmware.com) wrote:
>  
>
>>This code is quite dead.  Release_thread is always guaranteed that the mm has
>>already been released, thus dead_task->mm will always be NULL.
>>
>>Signed-off-by: Zachary Amsden <zach@vmware.com>
>>Index: linux-2.6.13/arch/i386/kernel/process.c
>>===================================================================
>>--- linux-2.6.13.orig/arch/i386/kernel/process.c	2005-08-15 10:46:18.000000000 -0700
>>+++ linux-2.6.13/arch/i386/kernel/process.c	2005-08-15 10:48:51.000000000 -0700
>>@@ -421,17 +421,7 @@
>> 
>> void release_thread(struct task_struct *dead_task)
>> {
>>-	if (dead_task->mm) {
>>-		// temporary debugging check
>>-		if (dead_task->mm->context.size) {
>>-			printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
>>-					dead_task->comm,
>>-					dead_task->mm->context.ldt,
>>-					dead_task->mm->context.size);
>>-			BUG();
>>-		}
>>-	}
>>-
>>+	BUG_ON(dead_task->mm);
>>    
>>
>
>This BUG_ON() has different semantics than old dead one.  Is there a
>point?  exit_mm() has already reset this to NULL, no?
>  
>

Yes, completely.  This BUG() could be eliminated entirely, as trivial 
inspection shows.  I can't fathom a single reason why it should still 
exist, but the presence of it in the first place made be wonder if there 
may be some erudite reason for it.  Thus I raised the BUG to a higher 
power - obviously the LDT is gone if the MM is gone.

Zach

      reply	other threads:[~2005-08-16  5:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-15 22:59 [PATCH 2/6] i386 virtualization - Remove some dead debugging code zach
2005-08-16  4:38 ` Chris Wright
2005-08-16  5:08   ` Zachary Amsden [this message]

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