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Date:   Tue, 22 Oct 2019 10:17:47 -0700
From:   Jakub Kicinski <jakub.kicinski@netronome.com>
To:     Daniel Wagner <dwagner@suse.de>
Cc:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        UNGLinuxDriver@microchip.com, netdev@vger.kernel.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-rt-users@vger.kernel.org,
        Woojung Huh <woojung.huh@microchip.com>,
        Marc Zyngier <maz@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
        Stefan Wahren <wahrenst@gmx.net>,
        Jisheng Zhang <Jisheng.Zhang@synaptics.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] net: usb: lan78xx: Use phy_mac_interrupt() for
 interrupt handling
Message-ID: <20191022101747.001b6d06@cakuba.netronome.com>
In-Reply-To: <20191018131532.dsfhyiilsi7cy4cm@linutronix.de>
References: <20191018082817.111480-1-dwagner@suse.de>
        <20191018131532.dsfhyiilsi7cy4cm@linutronix.de>
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On Fri, 18 Oct 2019 15:15:32 +0200, Sebastian Andrzej Siewior wrote:
> On 2019-10-18 10:28:17 [+0200], Daniel Wagner wrote:
> > handle_simple_irq() expect interrupts to be disabled. The USB
> > framework is using threaded interrupts, which implies that interrupts
> > are re-enabled as soon as it has run.  
> 
> Without threading interrupts, this is invoked in pure softirq context
> since commit ed194d1367698 ("usb: core: remove local_irq_save() around
> ->complete() handler") where the local_irq_disable() has been removed.  
> 
> This is probably not a problem because the lock is never observed with
> in IRQ context.
> 
> Wouldn't handle_nested_irq() work here instead of the simple thingy?

Daniel could you try this suggestion? Would it work?

I'm not sure we are at the stage yet where "doesn't work on -rt" is
sufficient reason to revert a working upstream patch. Please correct 
me if I'm wrong.