linux-kernel - Re: [PATCH 2/2] Replace pid_t in autofs with struct pid reference

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Message-ID: <m17itbmypc.fsf@ebiederm.dsl.xmission.com>
Date:	Tue, 20 Mar 2007 14:45:03 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	"Serge E. Hallyn" <serue@...ibm.com>
Cc:	Ian Kent <raven@...maw.net>, Cedric Le Goater <clg@...ibm.com>,
	sukadev@...ibm.com, Andrew Morton <akpm@...l.org>,
	Dave Hansen <haveblue@...ibm.com>,
	Herbert Poetzl <herbert@...hfloor.at>,
	containers@...ts.osdl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] Replace pid_t in autofs with struct pid reference

"Serge E. Hallyn" <serue@...ibm.com> writes:

> So how about the following on top of the patch Cedric sent out?
>
> Subject: [PATCH] autofs4: store struct pids in autofs_waitqs
> From: Serge Hallyn <serue@...ibm.com>
> Date: 1174412305 -0500
>
> Store struct pids in autofs_waitqs in place of pidnrs to prevent
> pid overflow problems.

At first skip it doesn't looks ok.

> Signed-off-by: Serge E. Hallyn <serue@...ibm.com>
>
> ---
>
>  fs/autofs4/autofs_i.h |   13 +++++++++++--
>  fs/autofs4/waitq.c    |   15 ++++++++-------
>  2 files changed, 19 insertions(+), 9 deletions(-)
>
> 86a5866c7672b88d48380504977496d5637642ab
> diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
> index 3ccec0a..5d119e3 100644
> --- a/fs/autofs4/autofs_i.h
> +++ b/fs/autofs4/autofs_i.h
> @@ -79,8 +79,8 @@ struct autofs_wait_queue {
>  	u64 ino;
>  	uid_t uid;
>  	gid_t gid;
> -	pid_t pid;
> -	pid_t tgid;
> +	struct pid *pid;
> +	struct pid *tgid;
>  	/* This is for status reporting upon return */
>  	int status;
>  	atomic_t wait_ctr;
> @@ -228,5 +228,14 @@ out:
>  	return ret;
>  }
>  
> +static void autofs_free_wait_queue(struct autofs_wait_queue *wq)
> +{
> +	if (wq->pid)
> +		put_pid(wq->pid);
> +	if (wq->tgid)
> +		put_pid(wq->tgid);
> +	kfree(wq);
> +}
> +
>  void autofs4_dentry_release(struct dentry *);
>  extern void autofs4_kill_sb(struct super_block *);
> diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> index 9857543..4a9ad9b 100644
> --- a/fs/autofs4/waitq.c
> +++ b/fs/autofs4/waitq.c
> @@ -141,8 +141,8 @@ static void autofs4_notify_daemon(struct
>  		packet->ino = wq->ino;
>  		packet->uid = wq->uid;
>  		packet->gid = wq->gid;
> -		packet->pid = wq->pid;
> -		packet->tgid = wq->tgid;
> +		packet->pid = pid_nr(wq->pid);
> +		packet->tgid = pid_nr(wq->tgid);
>  		break;

I'm assuming we build the packet in the process context of the
daemon we are sending it to.  If not we have a problem here.

>  	}
>  	default:
> @@ -292,8 +292,8 @@ int autofs4_wait(struct autofs_sb_info *
>  		wq->ino = autofs4_get_ino(sbi);
>  		wq->uid = current->uid;
>  		wq->gid = current->gid;
> -		wq->pid = pid_nr(task_pid(current));
> -		wq->tgid = pid_nr(task_tgid(current));
> +		wq->pid = get_pid(task_pid(current));
> +		wq->tgid = get_pid(task_tgid(current));
>  		wq->status = -EINTR; /* Status return if interrupted */
>  		atomic_set(&wq->wait_ctr, 2);
>  		mutex_unlock(&sbi->wq_mutex);
> @@ -360,8 +360,9 @@ int autofs4_wait(struct autofs_sb_info *
>  	status = wq->status;
>  
>  	/* Are we the last process to need status? */
> -	if (atomic_dec_and_test(&wq->wait_ctr))
> -		kfree(wq);
> +	if (atomic_dec_and_test(&wq->wait_ctr)) {
> +		autofs_free_wait_queue(wq);
> +	}

Unnecessary braces....
  
>  	return status;
>  }
> @@ -390,7 +391,7 @@ int autofs4_wait_release(struct autofs_s
>  	wq->status = status;
>  
>  	if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for
> this guy? */
> -		kfree(wq);
> +		autofs_free_wait_queue(wq);
>  	else
>  		wake_up_interruptible(&wq->queue);
>  
> -- 
> 1.1.6


Eric
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