From: Arnd Bergmann <arnd@arndb.de>
To: "Américo Wang" <xiyou.wangcong@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>, Greg KH <gregkh@suse.de>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
John Kacur <jkacur@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC 7/9] ppp: use big tty mutex
Date: Wed, 31 Mar 2010 09:39:14 +0200 [thread overview]
Message-ID: <201003310939.15324.arnd@arndb.de> (raw)
In-Reply-To: <2375c9f91003302137x7753a744pb2d2f0655738c7e4@mail.gmail.com>
On Wednesday 31 March 2010 06:37:12 Américo Wang wrote:
> > @@ -362,7 +362,8 @@ static const int npindex_to_ethertype[NUM_NP] = {
> > */
> > static int ppp_open(struct inode *inode, struct file *file)
> > {
> > - cycle_kernel_lock();
> > + tty_lock();
> > + tty_unlock();
>
> I don't really get your point here. :) Why do you do this?
This is a blind conversion of the API from the common BKL functions to
the TTY lock functions. There is no cycle_tty_lock(), so I'm manually
doing the cycle.
The reason why cycle_kernel_lock() was introduced in the first place
is that some drivers may depend on the open() function not returning
while another CPU holds the BKL. I did not feel qualified (or motivated)
to determine if the ppp code has the behavior, so I left it at this.
Arnd
next prev parent reply other threads:[~2010-03-31 7:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-30 20:56 [RFC 0/9] BKL conversion in TTY drivers Arnd Bergmann
2010-03-30 20:56 ` [RFC 1/9] tty: replace BKL with a new tty_lock Arnd Bergmann
2010-03-30 22:23 ` Frederic Weisbecker
2010-03-30 20:56 ` [RFC 2/9] tty: make atomic_write_lock release tty_lock Arnd Bergmann
2010-03-30 20:56 ` [RFC 3/9] tty: make tty_port->mutex nest under tty_lock Arnd Bergmann
2010-03-30 20:56 ` [RFC 4/9] tty: make termios mutex " Arnd Bergmann
2010-03-30 20:56 ` [RFC 5/9] tty: make ldisc_mutex " Arnd Bergmann
2010-03-30 20:56 ` [RFC 6/9] tty: never hold tty_lock() while getting tty_mutex Arnd Bergmann
2010-03-30 20:56 ` [RFC 7/9] ppp: use big tty mutex Arnd Bergmann
2010-03-31 4:37 ` Américo Wang
2010-03-31 7:39 ` Arnd Bergmann [this message]
2010-03-30 20:56 ` [RFC 8/9] tty: release tty lock when blocking Arnd Bergmann
2010-03-30 20:56 ` [RFC 9/9] tty: implement BTM as mutex instead of BKL Arnd Bergmann
2010-03-30 22:50 ` Frederic Weisbecker
2010-03-30 22:37 ` [RFC 0/9] BKL conversion in TTY drivers Alan Cox
2010-03-31 7:57 ` Arnd Bergmann
2010-03-31 10:02 ` Alan Cox
2010-04-01 12:51 ` Arnd Bergmann
2010-04-01 14:17 ` Alan Cox
2010-04-01 15:24 ` Greg KH
2010-04-01 19:10 ` Arnd Bergmann
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