linux-kernel - Re: [patch] x86: Unneeded assignment to tsk in recent x86 change

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Date:	Wed, 21 Jan 2009 14:06:35 +0100
From:	Mikael Pettersson <mikpe@...uu.se>
To:	Uros Bizjak <ubizjak@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [patch] x86: Unneeded assignment to tsk in recent x86 change

Uros Bizjak writes:
 > Hello!
 > 
 > Impact: Cleanup.
 > 
 > Remove unneeded assignment to tsk in recent x86 change [1].
 > 
 > [1]: http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-x86.git;a=commitdiff;h=d737c7649e2f7bdaa8760a9205dffaa45c117f20
 > 
 > Signed-off-by: Uros Bizjak <ubizjak@...il.com>
 > 
 > Patch vs. tip/master.
 > 
 > Uros.
 > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
 > index 93a563b..621e9b3 100644
 > --- a/arch/x86/mm/fault.c
 > +++ b/arch/x86/mm/fault.c
 > @@ -421,7 +421,6 @@ static noinline void pgtable_bad(struct pt_regs *regs,
 >  	printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
 >  	       tsk->comm, address);
 >  	dump_pagetable(address);
 > -	tsk = current;
 >  	tsk->thread.cr2 = address;
 >  	tsk->thread.trap_no = 14;
 >  	tsk->thread.error_code = error_code;

this bit is ok, clearly *tsk is valid and == current before the assignment

 > @@ -795,13 +794,12 @@ asmlinkage
 >  void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 >  {
 >  	unsigned long address;
 > -	struct task_struct *tsk;
 > +	struct task_struct *tsk = current;
 >  	struct mm_struct *mm;
 >  	struct vm_area_struct *vma;
 >  	int write;
 >  	int fault;
 >  
 > -	tsk = current;
 >  	mm = tsk->mm;
 >  	prefetchw(&mm->mmap_sem);

but this is neither a fix nor IMO a cleanup (it's inconsistent with
the other variables in that function)
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