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From: Johan Hovold <johan@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Johan Hovold <johan@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Ahmed S. Darwish" <a.darwish@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org,
	Thomas Winischhofer <thomas@winischhofer.net>,
	Mathias Nyman <mathias.nyman@intel.com>,
	Valentina Manea <valentina.manea.m@gmail.com>,
	Shuah Khan <shuah@kernel.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	linux-omap@vger.kernel.org, Kukjin Kim <kgene@kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org,
	Felipe Balbi <balbi@kernel.org>,
	Duncan Sands <duncan.sands@free.fr>
Subject: Re: [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage
Date: Tue, 27 Oct 2020 09:16:47 +0100	[thread overview]
Message-ID: <20201027081647.GC4085@localhost> (raw)
In-Reply-To: <20201026124753.btmdh3iwbwnff5dg@linutronix.de>

On Mon, Oct 26, 2020 at 01:47:53PM +0100, Sebastian Andrzej Siewior wrote:
> On 2020-10-25 17:56:47 [+0100], Johan Hovold wrote:
> > There's a ton of issues with this driver, but this is arguably making
> > things worse. A line discipline may call write() from just about any
> > context so we cannot rely on tty being non-NULL here (e.g. PPP).
> 
> I wasn't aware of that. I've been looking at the callers each time a
> `tty' was passed it looked like a preemptible context (due to mutex /
> GFP_KERNEL) and so on.

Yeah, the default line discipline only calls in preemptible context
(these days), but others do not (e.g. see ppp_async_push()).

Johan

WARNING: multiple messages have this Message-ID (diff)
From: Johan Hovold <johan@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Felipe Balbi <balbi@kernel.org>,
	Thomas Winischhofer <thomas@winischhofer.net>,
	Mathias Nyman <mathias.nyman@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, Johan Hovold <johan@kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-samsung-soc@vger.kernel.org, Kukjin Kim <kgene@kernel.org>,
	Valentina Manea <valentina.manea.m@gmail.com>,
	Duncan Sands <duncan.sands@free.fr>,
	"Ahmed S. Darwish" <a.darwish@linutronix.de>,
	Alan Stern <stern@rowland.harvard.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-omap@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage
Date: Tue, 27 Oct 2020 09:16:47 +0100	[thread overview]
Message-ID: <20201027081647.GC4085@localhost> (raw)
In-Reply-To: <20201026124753.btmdh3iwbwnff5dg@linutronix.de>

On Mon, Oct 26, 2020 at 01:47:53PM +0100, Sebastian Andrzej Siewior wrote:
> On 2020-10-25 17:56:47 [+0100], Johan Hovold wrote:
> > There's a ton of issues with this driver, but this is arguably making
> > things worse. A line discipline may call write() from just about any
> > context so we cannot rely on tty being non-NULL here (e.g. PPP).
> 
> I wasn't aware of that. I've been looking at the callers each time a
> `tty' was passed it looked like a preemptible context (due to mutex /
> GFP_KERNEL) and so on.

Yeah, the default line discipline only calls in preemptible context
(these days), but others do not (e.g. see ppp_async_push()).

Johan

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-10-27  8:16 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
2020-10-19 10:06 ` Thomas Gleixner
2020-10-19 10:06 ` [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 10:06 ` [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-25 16:56   ` Johan Hovold
2020-10-25 16:56     ` Johan Hovold
2020-10-26 12:47     ` Sebastian Andrzej Siewior
2020-10-26 12:47       ` Sebastian Andrzej Siewior
2020-10-27  8:16       ` Johan Hovold [this message]
2020-10-27  8:16         ` Johan Hovold
2020-10-19 10:06 ` [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-25 17:05   ` Johan Hovold
2020-10-25 17:05     ` Johan Hovold
2020-10-19 10:06 ` [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-25 17:16   ` Johan Hovold
2020-10-25 17:16     ` Johan Hovold
2020-10-26 14:03     ` [PATCH v3 04/13 ] " Sebastian Andrzej Siewior
2020-10-26 14:03       ` Sebastian Andrzej Siewior
2020-10-27  8:26       ` Johan Hovold
2020-10-27  8:26         ` Johan Hovold
2020-10-19 10:06 ` [patch V2 05/13] usb: xhci: Remove in_interrupt() checks Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 10:06 ` [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-28 11:27   ` Greg Kroah-Hartman
2020-10-28 11:27     ` Greg Kroah-Hartman
2020-10-19 10:06 ` [patch V2 07/13] usbip: Remove in_interrupt() check Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 10:06 ` [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 16:28     ` Alan Stern
2020-10-19 10:06 ` [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove() Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 16:28     ` Alan Stern
2020-10-19 10:06 ` [patch V2 10/13] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 10:06 ` [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 16:28     ` Alan Stern
2020-10-19 10:06 ` [patch V2 12/13] usb: core: Replace in_interrupt() in comments Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 16:28     ` Alan Stern
2020-10-19 10:06 ` [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
2020-10-19 10:06   ` Thomas Gleixner
2020-10-19 10:28   ` Duncan Sands
2020-10-19 10:28     ` Duncan Sands

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