From: Timur Tabi <timur@freescale.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: kumar.gala@freescale.com, linux-kernel@vger.kernel.org,
akpm@kernel.org, linux-console@vger.kernel.org, greg@kroah.com,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 6/7] tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver
Date: Thu, 19 May 2011 10:14:38 -0500 [thread overview]
Message-ID: <4DD533DE.1020705@freescale.com> (raw)
In-Reply-To: <20110519153358.5876f310@lxorguk.ukuu.org.uk>
Alan Cox wrote:
> ttys = tty_port_tty_get(&bc->port);
> stuff
> if (ttys != NULL)
> tty stuff
> tty_kref_put(ttys);
Under what circumstances can ttys be NULL? I currently only use this code in
the RX and TX interrupt handlers, which are both enabled in the
tty_port_operations.activate() function.
Is this right for the TX handler:
static irqreturn_t ehv_bc_tty_tx_isr(int irq, void *data)
{
struct ehv_bc_data *bc = data;
struct tty_struct *ttys = tty_port_tty_get(&bc->port);
ehv_bc_tx_dequeue(bc);
if (ttys) {
tty_wakeup(ttys);
tty_kref_put(ttys);
}
return IRQ_HANDLED;
}
I just want to make sure that testing for NULL is really necessary in my
interrupt handlers.
>> > + len = min_t(unsigned int,
>> > + CIRC_CNT_TO_END(bc->head, bc->tail, BUF_SIZE),
>> > + EV_BYTE_CHANNEL_MAX_BYTES);
> The kfifo API is probably faster and cleaner. Much of tty still uses
> CIRC_* because they predate the new APIs.
Ok, I'll change it.
> You really also need a hangup method so vhangup() does the right thing
> and you can securely do logins etc and sessions on your console. As
> you've got no hardware entangled in this and you already use tty_port
> helpers the hangup helper will do the work for you.
Ok.
>
> I guess the only other thing to consider is whether you want to implement
> a SYSRQ interface on your console ?
I don't think byte channels can support SYSRQ, but I'll look into it.
--
Timur Tabi
Linux kernel developer at Freescale
next prev parent reply other threads:[~2011-05-19 15:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-19 13:54 [PATCH 0/7] This patchset adds support for running Linux under the Freescale hypervisor, Timur Tabi
2011-05-19 13:54 ` [PATCH 1/7] powerpc: make irq_choose_cpu() available to all PIC drivers Timur Tabi
2011-06-22 11:41 ` Kumar Gala
2011-05-19 13:54 ` [PATCH 2/7] powerpc: introduce ePAPR embedded hypervisor hcall interface Timur Tabi
2011-06-22 11:41 ` Kumar Gala
2011-05-19 13:54 ` [PATCH 3/7] powerpc: introduce the ePAPR embedded hypervisor vmpic driver Timur Tabi
2011-06-22 11:41 ` Kumar Gala
2011-05-19 13:54 ` [PATCH 4/7] powerpc: add Freescale hypervisor partition control functions Timur Tabi
2011-06-22 11:41 ` Kumar Gala
2011-05-19 13:54 ` [PATCH 5/7] powerpc/85xx: add board support for the Freescale hypervisor Timur Tabi
2011-06-22 11:42 ` Kumar Gala
2011-05-19 13:54 ` [PATCH 6/7] tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver Timur Tabi
2011-05-19 14:22 ` Greg KH
2011-05-19 14:27 ` Timur Tabi
2011-05-19 14:36 ` Alan Cox
2011-05-19 14:33 ` Alan Cox
2011-05-19 15:14 ` Timur Tabi [this message]
2011-05-19 15:50 ` Alan Cox
2011-05-19 15:54 ` Timur Tabi
2011-05-19 16:00 ` Alan Cox
2011-05-19 16:02 ` Greg KH
2011-05-19 16:18 ` Timur Tabi
2011-05-19 16:05 ` Timur Tabi
2011-05-20 9:54 ` Alan Cox
2011-05-19 16:31 ` Timur Tabi
2011-05-19 17:25 ` Alan Cox
2011-05-19 15:02 ` Arnd Bergmann
2011-05-19 15:09 ` Timur Tabi
2011-05-19 13:54 ` [PATCH 7/7] drivers/misc: introduce Freescale hypervisor management driver Timur Tabi
2011-05-19 13:56 ` [PATCH 0/7] This patchset adds support for running Linux under the Freescale hypervisor, Timur Tabi
2011-05-20 20:29 ` Kumar Gala
2011-05-23 21:09 ` Tabi Timur-B04825
2011-05-23 22:27 ` Kumar Gala
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