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From: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
To: Wolfram Sang <wsa@kernel.org>
Cc: Ray Jui <ray.jui@broadcom.com>,
	Dhananjay Phadke <dphadke@linux.microsoft.com>,
	linux-i2c <linux-i2c@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ray Jui <rjui@broadcom.com>,
	BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>
Subject: Re: [PATCH] i2c: iproc: fix race between client unreg and isr
Date: Mon, 27 Jul 2020 10:02:09 +0530	[thread overview]
Message-ID: <CAHO=5PF6WmgTYAA8vVd86cx0YTx0CKouJ2k+13hNVCPiEtMVYA@mail.gmail.com> (raw)
In-Reply-To: <20200725101815.GA1519@ninjato>

On Sat, Jul 25, 2020 at 3:48 PM Wolfram Sang <wsa@kernel.org> wrote:
>
>
> > I think the following sequence needs to be implemented to make this
> > safe, i.e., after 'synchronize_irq', no further slave interrupt will be
> > fired.
> >
> > In 'bcm_iproc_i2c_unreg_slave':
> >
> > 1. Set an atomic variable 'unreg_slave' (I'm bad in names so please come
> > up with a better name than this)
> >
> > 2. Disable all slave interrupts
> >
> > 3. synchronize_irq
> >
> > 4. Set slave to NULL
> >
> > 5. Erase slave addresses
>
> What about this in unreg_slave?
>
> 1. disable_irq()
>         This includes synchronize_irq() and avoids the race. Because irq
>         will be masked at interrupt controller level, interrupts coming
>         in at the I2C IP core level should still be pending once we
>         reenable the irq.
>
> 2. disable all slave interrupts
>
> 3. enable_irq()
>
> 4. clean up the rest (pointer, address)
>
> Or am I overlooking something?

This sequence will take care of all cases.

@Dhananjay Phadke is it possible to verify this from your side once.

Best regards,
Raaygonda

  reply	other threads:[~2020-07-27  4:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-18 23:39 [PATCH] i2c: iproc: fix race between client unreg and isr Dhananjay Phadke
2020-07-19  7:59 ` Rayagonda Kokatanur
2020-07-20 17:40   ` Scott Branden
2020-07-20 17:49 ` Ray Jui
2020-07-22 10:41   ` Wolfram Sang
2020-07-22 15:51     ` Ray Jui
2020-07-22 16:55       ` Ray Jui
2020-07-23  0:58       ` Dhananjay Phadke
2020-07-25 10:18       ` Wolfram Sang
2020-07-27  4:32         ` Rayagonda Kokatanur [this message]
2020-07-27 15:42         ` Ray Jui
2020-07-27 17:38           ` Dhananjay Phadke
2020-07-27 18:13           ` Wolfram Sang
2020-07-27 20:26             ` Wolfram Sang
2020-07-27 20:43               ` Ray Jui
2020-08-05  9:17                 ` Wolfram Sang
2020-08-07 16:40                   ` Ray Jui
2020-08-07 17:38                     ` Dhananjay Phadke

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