linux-kernel - Re: [PATCH v2 01/11] uprobes: Introduce get

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Date:	Tue, 7 Jul 2015 14:44:42 +0200
From:	Anton Arapov <arapov@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ananth Mavinakayanahalli <ananth@...ibm.com>,
	David Long <dave.long@...aro.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	Jan Willeke <willeke@...ibm.com>,
	Jim Keniston <jkenisto@...ibm.com>,
	Mark Wielaard <mjw@...hat.com>,
	Pratyush Anand <panand@...hat.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/11] uprobes: Introduce get_uprobe()

On Tue, Jul 07, 2015 at 03:22:35AM +0200, Oleg Nesterov wrote:
> Cosmetic. Add the new trivial helper, get_uprobe(). It matches
> put_uprobe() we already have and we can simplify a couple of its
> users.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@...il.com>

> ---
>  kernel/events/uprobes.c |   39 ++++++++++++++++++++-------------------
>  1 files changed, 20 insertions(+), 19 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index cb346f2..a9847b4 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -366,6 +366,18 @@ set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long v
>  	return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn);
>  }
>  
> +static struct uprobe *get_uprobe(struct uprobe *uprobe)
> +{
> +	atomic_inc(&uprobe->ref);
> +	return uprobe;
> +}
> +
> +static void put_uprobe(struct uprobe *uprobe)
> +{
> +	if (atomic_dec_and_test(&uprobe->ref))
> +		kfree(uprobe);
> +}
> +
>  static int match_uprobe(struct uprobe *l, struct uprobe *r)
>  {
>  	if (l->inode < r->inode)
> @@ -393,10 +405,8 @@ static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
>  	while (n) {
>  		uprobe = rb_entry(n, struct uprobe, rb_node);
>  		match = match_uprobe(&u, uprobe);
> -		if (!match) {
> -			atomic_inc(&uprobe->ref);
> -			return uprobe;
> -		}
> +		if (!match)
> +			return get_uprobe(uprobe);
>  
>  		if (match < 0)
>  			n = n->rb_left;
> @@ -432,10 +442,8 @@ static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
>  		parent = *p;
>  		u = rb_entry(parent, struct uprobe, rb_node);
>  		match = match_uprobe(uprobe, u);
> -		if (!match) {
> -			atomic_inc(&u->ref);
> -			return u;
> -		}
> +		if (!match)
> +			return get_uprobe(u);
>  
>  		if (match < 0)
>  			p = &parent->rb_left;
> @@ -472,12 +480,6 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe)
>  	return u;
>  }
>  
> -static void put_uprobe(struct uprobe *uprobe)
> -{
> -	if (atomic_dec_and_test(&uprobe->ref))
> -		kfree(uprobe);
> -}
> -
>  static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
>  {
>  	struct uprobe *uprobe, *cur_uprobe;
> @@ -1039,14 +1041,14 @@ static void build_probe_list(struct inode *inode,
>  			if (u->inode != inode || u->offset < min)
>  				break;
>  			list_add(&u->pending_list, head);
> -			atomic_inc(&u->ref);
> +			get_uprobe(u);
>  		}
>  		for (t = n; (t = rb_next(t)); ) {
>  			u = rb_entry(t, struct uprobe, rb_node);
>  			if (u->inode != inode || u->offset > max)
>  				break;
>  			list_add(&u->pending_list, head);
> -			atomic_inc(&u->ref);
> +			get_uprobe(u);
>  		}
>  	}
>  	spin_unlock(&uprobes_treelock);
> @@ -1437,7 +1439,7 @@ static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
>  			return -ENOMEM;
>  
>  		*n = *o;
> -		atomic_inc(&n->uprobe->ref);
> +		get_uprobe(n->uprobe);
>  		n->next = NULL;
>  
>  		*p = n;
> @@ -1565,8 +1567,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
>  		orig_ret_vaddr = utask->return_instances->orig_ret_vaddr;
>  	}
>  
> -	atomic_inc(&uprobe->ref);
> -	ri->uprobe = uprobe;
> +	ri->uprobe = get_uprobe(uprobe);
>  	ri->func = instruction_pointer(regs);
>  	ri->orig_ret_vaddr = orig_ret_vaddr;
>  	ri->chained = chained;
> -- 
> 1.5.5.1
> 
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