From: Andrew Morton <akpm@osdl.org>
To: Ryan Arnold <rsa@us.ibm.com>
Cc: linux-kernel@vger.kernel.org, linuxppc64-dev@lists.linuxppc.org,
paulus@samba.org, benh@kernel.crashing.org
Subject: Re: [PATCH] interrupt driven hvc_console as vio device
Date: Tue, 24 Aug 2004 21:49:50 -0700 [thread overview]
Message-ID: <20040824214950.5d9043a3.akpm@osdl.org> (raw)
In-Reply-To: <1093394937.3402.83.camel@localhost>
Ryan Arnold <rsa@us.ibm.com> wrote:
>
> static int hvc_write_room(struct tty_struct *tty)
> {
> struct hvc_struct *hp = tty->driver_data;
> + unsigned long flags;
> + int retval;
>
> - return N_OUTBUF - hp->n_outbuf;
> + spin_lock_irqsave(&hp->lock, flags);
> + retval = N_OUTBUF - hp->n_outbuf;
> + spin_unlock_irqrestore(&hp->lock, flags);
> + return retval;
> }
>
> static int hvc_chars_in_buffer(struct tty_struct *tty)
> {
> struct hvc_struct *hp = tty->driver_data;
> + unsigned long flags;
> + int retval;
>
> - return hp->n_outbuf;
> + spin_lock_irqsave(&hp->lock, flags);
> + retval = hp->n_outbuf;
> + spin_unlock_irqrestore(&hp->lock, flags);
> + return retval;
> }
The new locking in these functions doesn't really do anything, apart from
adding memory barriers. If that's what you really want, I suggest you
simply add (commented) memory barriers.
next prev parent reply other threads:[~2004-08-25 4:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-25 0:48 Ryan Arnold
2004-08-25 4:46 ` Andrew Morton
2004-08-25 5:09 ` Ryan Arnold
2004-08-25 4:49 ` Andrew Morton [this message]
2004-08-25 5:12 ` Ryan Arnold
2004-08-25 4:59 ` Paul Mackerras
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