linux-kernel - Re: [PATCH 3/4] uprobes: rename vma_address() and make it return "unsigned long"

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Message-ID: <20120727062223.GA3906@linux.vnet.ibm.com>
Date:	Fri, 27 Jul 2012 11:52:23 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] uprobes: rename vma_address() and make it return
 "unsigned long"

* Oleg Nesterov <oleg@...hat.com> [2012-07-26 12:28:12]:

> On 07/26, Srikar Dronamraju wrote:
> >
> > * Oleg Nesterov <oleg@...hat.com> [2012-07-12 19:10:22]:
> >
> > > 1. vma_address() returns loff_t, this looks confusing and this is
> > >    unnecessary after the previous change. Make it return "ulong",
> > >    all callers truncate the result anyway.
> > >
> > > 2. Its name conflicts with mm/rmap.c:vma_address(), rename it to
> > >    offset_to_vaddr(), this matches vaddr_to_offset().
> > >
> > > Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> >
> > Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> 
> Thanks.
> 
> Could you please ack v2 below?
> 
> I forgot to update "loff_t vaddr" in mmap/munmap. IOW, this is the
> same patch plus
> 
> 	- loff_t vaddr = offset_to_vaddr(...);
> 	+ unsigned long vaddr = offset_to_vaddr(...);
> 
> in uprobe_mmap/munmap.
> 

Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

> In fact I was going to do this in
> "uprobes: teach build_probe_list() to consider the range" but
> forgot as well.
> 
> Oleg.
> 
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -112,14 +112,9 @@ static bool valid_vma(struct vm_area_struct *vma, bool is_register)
>  	return false;
>  }
> 
> -static loff_t vma_address(struct vm_area_struct *vma, loff_t offset)
> +static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
>  {
> -	loff_t vaddr;
> -
> -	vaddr = vma->vm_start + offset;
> -	vaddr -= (loff_t)vma->vm_pgoff << PAGE_SHIFT;
> -
> -	return vaddr;
> +	return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
>  }
> 
>  static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
> @@ -775,7 +770,7 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
>  		curr = info;
> 
>  		info->mm = vma->vm_mm;
> -		info->vaddr = vma_address(vma, offset);
> +		info->vaddr = offset_to_vaddr(vma, offset);
>  	}
>  	mutex_unlock(&mapping->i_mmap_mutex);
> 
> @@ -1042,7 +1037,7 @@ int uprobe_mmap(struct vm_area_struct *vma)
> 
>  	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
>  		if (!ret) {
> -			loff_t vaddr = vma_address(vma, uprobe->offset);
> +			unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
> 
>  			ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
>  			/*
> @@ -1103,7 +1098,7 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
>  	build_probe_list(inode, vma, start, end, &tmp_list);
> 
>  	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
> -		loff_t vaddr = vma_address(vma, uprobe->offset);
> +		unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
>  		/*
>  		 * An unregister could have removed the probe before
>  		 * unmap. So check before we decrement the count.
> 

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