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

From: Mikael Pettersson
Date: Wed Jan 21 2009 - 08:06:50 EST


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@xxxxxxxxx>
>
> 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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