netdev - Re: [PATCH 1/2] net: ethernet: cpsw: don't claim IRQs with devm_request

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Date:	Wed, 3 Sep 2014 12:57:37 +0530
From:	Mugunthan V N <mugunthanvnm@...com>
To:	Daniel Mack <zonque@...il.com>, <davem@...emloft.net>
CC:	<julia.lawall@...6.fr>, <netdev@...r.kernel.org>,
	<george.cherian@...com>
Subject: Re: [PATCH 1/2] net: ethernet: cpsw: don't claim IRQs with devm_request_irq()

On Tuesday 02 September 2014 10:14 PM, Daniel Mack wrote:
> Julia Lawall spotted a problem with aa1a15e ("net: ethernet: cpsw:
> switch to devres allocations") which introduced a race condition in
> cpsw_probe() by removing explicit interrupt disable calls before
> calling free_netdev(). Hence, an interrupt can fire after free_netdev()
> was called. The same problem exists in cpsw_remove().
> 
> Fix this by reverting the IRQ part of the aforementioned patch and
> handle those resources explicitly.
> 
> Reported-by: Julia Lawall <julia.lawall@...6.fr>
> Signed-off-by: Daniel Mack <zonque@...il.com>

CPSW interrupts cannot be triggered as the interrupts are disabled in
priv->wr_regs->tx_en and priv->wr_regs->rx_en inside CPSW module and
these interrupts are enabled only when the device is opened.

In cpsw_remove, CPDMA controller is stopped and interrupts are disabled
in cpsw_ndo_stop(), so there is no chance that an interrupt can occur
during cpsw_remove().

Regards
Mugunthan V N
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