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From: Thomas Monjalon <thomas@monjalon.net>
To: Ferruh Yigit <ferruh.yigit@intel.com>
Cc: dev@dpdk.org, stable@dpdk.org, Jianfeng Tan <jianfeng.tan@intel.com>,
Jingjing Wu <jingjing.wu@intel.com>,
Shijith Thotton <shijith.thotton@caviumnetworks.com>,
Gregory Etelson <gregory@weka.io>, Harish Patil <harish.patil@cavium.com>,
George Prekas <george.prekas@epfl.ch>,
Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>,
Rasesh Mody <rasesh.mody@cavium.com>, Lee Roberts <lee.roberts@hpe.com>,
Stephen Hemminger <stephen@networkplumber.org>, Chas Williams <chas3@att.com>
Date: Wed, 08 Nov 2017 00:57:17 +0100
Message-ID: <10440492.mlt1TGbLnU@xps>
In-Reply-To: <20171107222913.65295-1-ferruh.yigit@intel.com>
References: <20171107193217.56357-1-ferruh.yigit@intel.com>
<20171107222913.65295-1-ferruh.yigit@intel.com>
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Subject: Re: [dpdk-dev] [PATCH v2] igb_uio: remove device reset in release
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07/11/2017 23:29, Ferruh Yigit:
> More error reported for device reset in release() [1],
> when device pass-through to the guest, host kernel crash on guest exit.
>
> Removing the reset completely.
>
> This is close to reverting commit b58eedfc7dd5 [2], taking into account
> previous fix to remove reset in open as well [3], but not exactly same.
>
> With latest code, interrupts are enabled in uio open() callback and
> disabled in uio release() callback, so when a DPDK application exit
> device interrupts are disabled. Previously interrupts were only enabled
> once in igb_uio module insert and disabled in module removal.
>
> Also with latest code device set as bus master in open() and master
> cleared in release(), clearing bus master should prevent further DMA
> which was one of the target of the initial patch.
>
> The initial intention was also to reset the device to be sure it has
> been left in proper state, but currently that part is missing because of
> reported problem(s).
>
> Still igb_uio should be safer comparing to the pre b58eedfc7dd5 state.
>
> [1]
> http://dpdk.org/ml/archives/dev/2017-November/081459.html
>
> [2]
> b58eedfc7dd5 ("igb_uio: issue FLR during open and release of device file")
>
> [3]
> f73b38e9245d ("igb_uio: remove device reset in open")
>
> Fixes: e3a64deae2d5 ("igb_uio: prevent reset for bnx2x devices")
> Fixes: b58eedfc7dd5 ("igb_uio: issue FLR during open and release of device file")
> Cc: stable@dpdk.org
>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
We can say you tried hard to make igb_uio cleaner and safer :)
Applied, thanks for the detailed explanations.